Upgrading from 9.5.1 to 9.6.7 gives you 2.1 years worth of changes and fixes (620 of them)

List of changes:

• ⇑ Upgrade to 9.5.2 released on 2016-03-31 - docs

  • Disable abbreviated keys for string sorting in non-C locales (Robert Haas)

    PostgreSQL 9.5 introduced logic for speeding up comparisons of string data types by using the standard C library function strxfrm() as a substitute for strcoll(). It now emerges that most versions of glibc (Linux's implementation of the C library) have buggy implementations of strxfrm() that, in some locales, can produce string comparison results that do not match strcoll(). Until this problem can be better characterized, disable the optimization in all non-C locales. (C locale is safe since it uses neither strcoll() nor strxfrm().)

    Unfortunately, this problem affects not only sorting but also entry ordering in B-tree indexes, which means that B-tree indexes on text, varchar, or char columns may now be corrupt if they sort according to an affected locale and were built or modified under PostgreSQL 9.5.0 or 9.5.1. Users should REINDEX indexes that might be affected.

    It is not possible at this time to give an exhaustive list of known-affected locales. C locale is known safe, and there is no evidence of trouble in English-based locales such as en_US, but some other popular locales such as de_DE are affected in most glibc versions.

  • Maintain row-security status properly in cached plans (Stephen Frost)

    In a session that performs queries as more than one role, the plan cache might incorrectly re-use a plan that was generated for another role ID, thus possibly applying the wrong set of policies when row-level security (RLS) is in use. (CVE-2016-2193)

  • Add must-be-superuser checks to some new contrib/pageinspect functions (Andreas Seltenreich)

    Most functions in the pageinspect extension that inspect bytea values disallow calls by non-superusers, but brin_page_type() and brin_metapage_info() failed to do so. Passing contrived bytea values to them might crash the server or disclose a few bytes of server memory. Add the missing permissions checks to prevent misuse. (CVE-2016-3065)

  • Fix incorrect handling of indexed ROW() comparisons (Simon Riggs)

    Flaws in a minor optimization introduced in 9.5 caused incorrect results if the ROW() comparison matches the index ordering partially but not exactly (for example, differing column order, or the index contains both ASC and DESC columns). Pending a better solution, the optimization has been removed.

  • Fix incorrect handling of NULL index entries in indexed ROW() comparisons (Tom Lane)

    An index search using a row comparison such as ROW(a, b) > ROW('x', 'y') would stop upon reaching a NULL entry in the b column, ignoring the fact that there might be non-NULL b values associated with later values of a.

  • Avoid unlikely data-loss scenarios due to renaming files without adequate fsync() calls before and after (Michael Paquier, Tomas Vondra, Andres Freund)

  • Fix incorrect behavior when rechecking a just-modified row in a query that does SELECT FOR UPDATE/SHARE and contains some relations that need not be locked (Tom Lane)

    Rows from non-locked relations were incorrectly treated as containing all NULLs during the recheck, which could result in incorrectly deciding that the updated row no longer passes the WHERE condition, or in incorrectly outputting NULLs.

  • Fix bug in json_to_record() when a field of its input object contains a sub-object with a field name matching one of the requested output column names (Tom Lane)

  • Fix nonsense result from two-argument form of jsonb_object() when called with empty arrays (Michael Paquier, Andrew Dunstan)

  • Fix misbehavior in jsonb_set() when converting a path array element into an integer for use as an array subscript (Michael Paquier)

  • Fix misformatting of negative time zone offsets by to_char()'s OF format code (Thomas Munro, Tom Lane)

  • Fix possible incorrect logging of waits done by INSERT ... ON CONFLICT (Peter Geoghegan)

    Log messages would sometimes claim that the wait was due to an exclusion constraint although no such constraint was responsible.

  • Ignore recovery_min_apply_delay parameter until recovery has reached a consistent state (Michael Paquier)

    Previously, standby servers would delay application of WAL records in response to recovery_min_apply_delay even while replaying the initial portion of WAL needed to make their database state valid. Since the standby is useless until it's reached a consistent database state, this was deemed unhelpful.

  • Correctly handle cases where pg_subtrans is close to XID wraparound during server startup (Jeff Janes)

  • Fix assorted bugs in logical decoding (Andres Freund)

    Trouble cases included tuples larger than one page when replica identity is FULL, UPDATEs that change a primary key within a transaction large enough to be spooled to disk, incorrect reports of "subxact logged without previous toplevel record", and incorrect reporting of a transaction's commit time.

  • Fix planner error with nested security barrier views when the outer view has a WHERE clause containing a correlated subquery (Dean Rasheed)

  • Fix memory leak in GIN index searches (Tom Lane)

  • Fix corner-case crash due to trying to free localeconv() output strings more than once (Tom Lane)

  • Fix parsing of affix files for ispell dictionaries (Tom Lane)

    The code could go wrong if the affix file contained any characters whose byte length changes during case-folding, for example I in Turkish UTF8 locales.

  • Avoid use of sscanf() to parse ispell dictionary files (Artur Zakirov)

    This dodges a portability problem on FreeBSD-derived platforms (including macOS).

  • Fix atomic-operations code used on PPC with IBM's xlc compiler (Noah Misch)

    This error led to rare failures of concurrent operations on that platform.

  • Avoid a crash on old Windows versions (before 7SP1/2008R2SP1) with an AVX2-capable CPU and a Postgres build done with Visual Studio 2013 (Christian Ullrich)

    This is a workaround for a bug in Visual Studio 2013's runtime library, which Microsoft have stated they will not fix in that version.

  • Fix psql's tab completion logic to handle multibyte characters properly (Kyotaro Horiguchi, Robert Haas)

  • Fix psql's tab completion for SECURITY LABEL (Tom Lane)

    Pressing TAB after SECURITY LABEL might cause a crash or offering of inappropriate keywords.

  • Make pg_ctl accept a wait timeout from the PGCTLTIMEOUT environment variable, if none is specified on the command line (Noah Misch)

    This eases testing of slower buildfarm members by allowing them to globally specify a longer-than-normal timeout for postmaster startup and shutdown.

  • Fix incorrect test for Windows service status in pg_ctl (Manuel Mathar)

    The previous set of minor releases attempted to fix pg_ctl to properly determine whether to send log messages to Window's Event Log, but got the test backwards.

  • Fix pgbench to correctly handle the combination of -C and -M prepared options (Tom Lane)

  • In pg_upgrade, skip creating a deletion script when the new data directory is inside the old data directory (Bruce Momjian)

    Blind application of the script in such cases would result in loss of the new data directory.

  • In PL/Perl, properly translate empty Postgres arrays into empty Perl arrays (Alex Hunsaker)

  • Make PL/Python cope with function names that aren't valid Python identifiers (Jim Nasby)

  • Fix multiple mistakes in the statistics returned by contrib/pgstattuple's pgstatindex() function (Tom Lane)

  • Remove dependency on psed in MSVC builds, since it's no longer provided by core Perl (Michael Paquier, Andrew Dunstan)

  • Update time zone data files to tzdata release 2016c for DST law changes in Azerbaijan, Chile, Haiti, Palestine, and Russia (Altai, Astrakhan, Kirov, Sakhalin, Ulyanovsk regions), plus historical corrections for Lithuania, Moldova, and Russia (Kaliningrad, Samara, Volgograd).

• ⇑ Upgrade to 9.5.3 released on 2016-05-12 - docs

  • Clear the OpenSSL error queue before OpenSSL calls, rather than assuming it's clear already; and make sure we leave it clear afterwards (Peter Geoghegan, Dave Vitek, Peter Eisentraut)

    This change prevents problems when there are multiple connections using OpenSSL within a single process and not all the code involved follows the same rules for when to clear the error queue. Failures have been reported specifically when a client application uses SSL connections in libpq concurrently with SSL connections using the PHP, Python, or Ruby wrappers for OpenSSL. It's possible for similar problems to arise within the server as well, if an extension module establishes an outgoing SSL connection.

  • Fix "failed to build any N-way joins" planner error with a full join enclosed in the right-hand side of a left join (Tom Lane)

  • Fix incorrect handling of equivalence-class tests in multilevel nestloop plans (Tom Lane)

    Given a three-or-more-way equivalence class of variables, such as X.X = Y.Y = Z.Z, it was possible for the planner to omit some of the tests needed to enforce that all the variables are actually equal, leading to join rows being output that didn't satisfy the WHERE clauses. For various reasons, erroneous plans were seldom selected in practice, so that this bug has gone undetected for a long time.

  • Fix corner-case parser failures occurring when operator_precedence_warning is turned on (Tom Lane)

    An example is that SELECT (ARRAY[])::text[] gave an error, though it worked without the parentheses.

  • Fix query-lifespan memory leak in GIN index scans (Julien Rouhaud)

  • Fix query-lifespan memory leak and potential index corruption hazard in GIN index insertion (Tom Lane)

    The memory leak would typically not amount to much in simple queries, but it could be very substantial during a large GIN index build with high maintenance_work_mem.

  • Fix possible misbehavior of TH, th, and Y,YYY format codes in to_timestamp() (Tom Lane)

    These could advance off the end of the input string, causing subsequent format codes to read garbage.

  • Fix dumping of rules and views in which the array argument of a value operator ANY (array) construct is a sub-SELECT (Tom Lane)

  • Disallow newlines in ALTER SYSTEM parameter values (Tom Lane)

    The configuration-file parser doesn't support embedded newlines in string literals, so we mustn't allow them in values to be inserted by ALTER SYSTEM.

  • Fix ALTER TABLE ... REPLICA IDENTITY USING INDEX to work properly if an index on OID is selected (David Rowley)

  • Avoid possible misbehavior after failing to remove a tablespace symlink (Tom Lane)

  • Fix crash in logical decoding on alignment-picky platforms (Tom Lane, Andres Freund)

    The failure occurred only with a transaction large enough to spill to disk and a primary-key change within that transaction.

  • Avoid repeated requests for feedback from receiver while shutting down walsender (Nick Cleaton)

  • Make pg_regress use a startup timeout from the PGCTLTIMEOUT environment variable, if that's set (Tom Lane)

    This is for consistency with a behavior recently added to pg_ctl; it eases automated testing on slow machines.

  • Fix pg_upgrade to correctly restore extension membership for operator families containing only one operator class (Tom Lane)

    In such a case, the operator family was restored into the new database, but it was no longer marked as part of the extension. This had no immediate ill effects, but would cause later pg_dump runs to emit output that would cause (harmless) errors on restore.

  • Fix pg_upgrade to not fail when new-cluster TOAST rules differ from old (Tom Lane)

    pg_upgrade had special-case code to handle the situation where the new PostgreSQL version thinks that a table should have a TOAST table while the old version did not. That code was broken, so remove it, and instead do nothing in such cases; there seems no reason to believe that we can't get along fine without a TOAST table if that was okay according to the old version's rules.

  • Fix atomic operations for PPC when using IBM's XLC compiler (Noah Misch)

  • Reduce the number of SysV semaphores used by a build configured with --disable-spinlocks (Tom Lane)

  • Rename internal function strtoi() to strtoint() to avoid conflict with a NetBSD library function (Thomas Munro)

  • Fix reporting of errors from bind() and listen() system calls on Windows (Tom Lane)

  • Reduce verbosity of compiler output when building with Microsoft Visual Studio (Christian Ullrich)

  • Support building with Visual Studio 2015 (Michael Paquier, Petr Jelínek)

    Note that builds made with VS2015 will not run on Windows versions before Windows Vista.

  • Fix putenv() to work properly with Visual Studio 2013 (Michael Paquier)

  • Avoid possibly-unsafe use of Windows' FormatMessage() function (Christian Ullrich)

    Use the FORMAT_MESSAGE_IGNORE_INSERTS flag where appropriate. No live bug is known to exist here, but it seems like a good idea to be careful.

  • Update time zone data files to tzdata release 2016d for DST law changes in Russia and Venezuela. There are new zone names Europe/Kirov and Asia/Tomsk to reflect the fact that these regions now have different time zone histories from adjacent regions.

• ⇑ Upgrade to 9.5.4 released on 2016-08-11 - docs

  • Fix possible mis-evaluation of nested CASE-WHEN expressions (Heikki Linnakangas, Michael Paquier, Tom Lane)

    A CASE expression appearing within the test value subexpression of another CASE could become confused about whether its own test value was null or not. Also, inlining of a SQL function implementing the equality operator used by a CASE expression could result in passing the wrong test value to functions called within a CASE expression in the SQL function's body. If the test values were of different data types, a crash might result; moreover such situations could be abused to allow disclosure of portions of server memory. (CVE-2016-5423)

  • Fix client programs' handling of special characters in database and role names (Noah Misch, Nathan Bossart, Michael Paquier)

    Numerous places in vacuumdb and other client programs could become confused by database and role names containing double quotes or backslashes. Tighten up quoting rules to make that safe. Also, ensure that when a conninfo string is used as a database name parameter to these programs, it is correctly treated as such throughout.

    Fix handling of paired double quotes in psql's \connect and \password commands to match the documentation.

    Introduce a new -reuse-previous option in psql's \connect command to allow explicit control of whether to re-use connection parameters from a previous connection. (Without this, the choice is based on whether the database name looks like a conninfo string, as before.) This allows secure handling of database names containing special characters in pg_dumpall scripts.

    pg_dumpall now refuses to deal with database and role names containing carriage returns or newlines, as it seems impractical to quote those characters safely on Windows. In future we may reject such names on the server side, but that step has not been taken yet.

    These are considered security fixes because crafted object names containing special characters could have been used to execute commands with superuser privileges the next time a superuser executes pg_dumpall or other routine maintenance operations. (CVE-2016-5424)

  • Fix corner-case misbehaviors for IS NULL/IS NOT NULL applied to nested composite values (Andrew Gierth, Tom Lane)

    The SQL standard specifies that IS NULL should return TRUE for a row of all null values (thus ROW(NULL,NULL) IS NULL yields TRUE), but this is not meant to apply recursively (thus ROW(NULL, ROW(NULL,NULL)) IS NULL yields FALSE). The core executor got this right, but certain planner optimizations treated the test as recursive (thus producing TRUE in both cases), and contrib/postgres_fdw could produce remote queries that misbehaved similarly.

  • Fix "unrecognized node type" error for INSERT ... ON CONFLICT within a recursive CTE (a WITH item) (Peter Geoghegan)

  • Fix INSERT ... ON CONFLICT to successfully match index expressions or index predicates that are simplified during the planner's expression preprocessing phase (Tom Lane)

  • Correctly handle violations of exclusion constraints that apply to the target table of an INSERT ... ON CONFLICT command, but are not one of the selected arbiter indexes (Tom Lane)

    Such a case should raise a normal constraint-violation error, but it got into an infinite loop instead.

  • Fix INSERT ... ON CONFLICT to not fail if the target table has a unique index on OID (Tom Lane)

  • Make the inet and cidr data types properly reject IPv6 addresses with too many colon-separated fields (Tom Lane)

  • Prevent crash in close_ps() (the point ## lseg operator) for NaN input coordinates (Tom Lane)

    Make it return NULL instead of crashing.

  • Avoid possible crash in pg_get_expr() when inconsistent values are passed to it (Michael Paquier, Thomas Munro)

  • Fix several one-byte buffer over-reads in to_number() (Peter Eisentraut)

    In several cases the to_number() function would read one more character than it should from the input string. There is a small chance of a crash, if the input happens to be adjacent to the end of memory.

  • Do not run the planner on the query contained in CREATE MATERIALIZED VIEW or CREATE TABLE AS when WITH NO DATA is specified (Michael Paquier, Tom Lane)

    This avoids some unnecessary failure conditions, for example if a stable function invoked by the materialized view depends on a table that doesn't exist yet.

  • Avoid unsafe intermediate state during expensive paths through heap_update() (Masahiko Sawada, Andres Freund)

    Previously, these cases locked the target tuple (by setting its XMAX) but did not WAL-log that action, thus risking data integrity problems if the page were spilled to disk and then a database crash occurred before the tuple update could be completed.

  • Fix hint bit update during WAL replay of row locking operations (Andres Freund)

    The only known consequence of this problem is that row locks held by a prepared, but uncommitted, transaction might fail to be enforced after a crash and restart.

  • Avoid unnecessary "could not serialize access" errors when acquiring FOR KEY SHARE row locks in serializable mode (Álvaro Herrera)

  • Make sure "expanded" datums returned by a plan node are read-only (Tom Lane)

    This avoids failures in some cases where the result of a lower plan node is referenced in multiple places in upper nodes. So far as core PostgreSQL is concerned, only array values returned by PL/pgSQL functions are at risk; but extensions might use expanded datums for other things.

  • Avoid crash in postgres -C when the specified variable has a null string value (Michael Paquier)

  • Prevent unintended waits for the receiver in WAL sender processes (Kyotaro Horiguchi)

  • Fix possible loss of large subtransactions in logical decoding (Petru-Florin Mihancea)

  • Fix failure of logical decoding when a subtransaction contains no actual changes (Marko Tiikkaja, Andrew Gierth)

  • Ensure that backends see up-to-date statistics for shared catalogs (Tom Lane)

    The statistics collector failed to update the statistics file for shared catalogs after a request from a regular backend. This problem was partially masked because the autovacuum launcher regularly makes requests that did cause such updates; however, it became obvious with autovacuum disabled.

  • Avoid redundant writes of the statistics files when multiple backends request updates close together (Tom Lane, Tomas Vondra)

  • Avoid consuming a transaction ID during VACUUM (Alexander Korotkov)

    Some cases in VACUUM unnecessarily caused an XID to be assigned to the current transaction. Normally this is negligible, but if one is up against the XID wraparound limit, consuming more XIDs during anti-wraparound vacuums is a very bad thing.

  • Prevent possible failure when vacuuming multixact IDs in an installation that has been pg_upgrade'd from pre-9.3 (Andrew Gierth, Álvaro Herrera)

    The usual symptom of this bug is errors like "MultiXactId NNN has not been created yet -- apparent wraparound".

  • When a manual ANALYZE specifies a column list, don't reset the table's changes_since_analyze counter (Tom Lane)

    If we're only analyzing some columns, we should not prevent routine auto-analyze from happening for the other columns.

  • Fix ANALYZE's overestimation of n_distinct for a unique or nearly-unique column with many null entries (Tom Lane)

    The nulls could get counted as though they were themselves distinct values, leading to serious planner misestimates in some types of queries.

  • Prevent autovacuum from starting multiple workers for the same shared catalog (Álvaro Herrera)

    Normally this isn't much of a problem because the vacuum doesn't take long anyway; but in the case of a severely bloated catalog, it could result in all but one worker uselessly waiting instead of doing useful work on other tables.

  • Fix bug in b-tree mark/restore processing (Kevin Grittner)

    This error could lead to incorrect join results or assertion failures in a merge join whose inner source node is a b-tree indexscan.

  • Avoid duplicate buffer lock release when abandoning a b-tree index page deletion attempt (Tom Lane)

    This mistake prevented VACUUM from completing in some cases involving corrupt b-tree indexes.

  • Fix building of large (bigger than shared_buffers) hash indexes (Tom Lane)

    The code path used for large indexes contained a bug causing incorrect hash values to be inserted into the index, so that subsequent index searches always failed, except for tuples inserted into the index after the initial build.

  • Prevent infinite loop in GiST index build for geometric columns containing NaN component values (Tom Lane)

  • Fix possible crash during a nearest-neighbor (ORDER BY distance) indexscan on a contrib/btree_gist index on an interval column (Peter Geoghegan)

  • Fix "PANIC: failed to add BRIN tuple" error when attempting to update a BRIN index entry (Álvaro Herrera)

  • Fix possible crash during background worker shutdown (Dmitry Ivanov)

  • Fix PL/pgSQL's handling of the INTO clause within IMPORT FOREIGN SCHEMA commands (Tom Lane)

  • Fix contrib/btree_gin to handle the smallest possible bigint value correctly (Peter Eisentraut)

  • Teach libpq to correctly decode server version from future servers (Peter Eisentraut)

    It's planned to switch to two-part instead of three-part server version numbers for releases after 9.6. Make sure that PQserverVersion() returns the correct value for such cases.

  • Fix ecpg's code for unsigned long long array elements (Michael Meskes)

  • In pg_dump with both -c and -C options, avoid emitting an unwanted CREATE SCHEMA public command (David Johnston, Tom Lane)

  • Improve handling of SIGTERM/control-C in parallel pg_dump and pg_restore (Tom Lane)

    Make sure that the worker processes will exit promptly, and also arrange to send query-cancel requests to the connected backends, in case they are doing something long-running such as a CREATE INDEX.

  • Fix error reporting in parallel pg_dump and pg_restore (Tom Lane)

    Previously, errors reported by pg_dump or pg_restore worker processes might never make it to the user's console, because the messages went through the master process, and there were various deadlock scenarios that would prevent the master process from passing on the messages. Instead, just print everything to stderr. In some cases this will result in duplicate messages (for instance, if all the workers report a server shutdown), but that seems better than no message.

  • Ensure that parallel pg_dump or pg_restore on Windows will shut down properly after an error (Kyotaro Horiguchi)

    Previously, it would report the error, but then just sit until manually stopped by the user.

  • Make parallel pg_dump fail cleanly when run against a standby server (Magnus Hagander)

    This usage is not supported unless --no-synchronized-snapshots is specified, but the error was not handled very well.

  • Make pg_dump behave better when built without zlib support (Kyotaro Horiguchi)

    It didn't work right for parallel dumps, and emitted some rather pointless warnings in other cases.

  • Make pg_basebackup accept -Z 0 as specifying no compression (Fujii Masao)

  • Fix makefiles' rule for building AIX shared libraries to be safe for parallel make (Noah Misch)

  • Fix TAP tests and MSVC scripts to work when build directory's path name contains spaces (Michael Paquier, Kyotaro Horiguchi)

  • Be more predictable about reporting "statement timeout" versus "lock timeout" (Tom Lane)

    On heavily loaded machines, the regression tests sometimes failed due to reporting "lock timeout" even though the statement timeout should have occurred first.

  • Make regression tests safe for Danish and Welsh locales (Jeff Janes, Tom Lane)

    Change some test data that triggered the unusual sorting rules of these locales.

  • Update our copy of the timezone code to match IANA's tzcode release 2016c (Tom Lane)

    This is needed to cope with anticipated future changes in the time zone data files. It also fixes some corner-case bugs in coping with unusual time zones.

  • Update time zone data files to tzdata release 2016f for DST law changes in Kemerovo and Novosibirsk, plus historical corrections for Azerbaijan, Belarus, and Morocco.

• ⇑ Upgrade to 9.6 released on 2016-09-29 - docs

  • Improve the pg_stat_activity view's information about what a process is waiting for (Amit Kapila, Ildus Kurbangaliev)

    Historically a process has only been shown as waiting if it was waiting for a heavyweight lock. Now waits for lightweight locks and buffer pins are also shown in pg_stat_activity. Also, the type of lock being waited for is now visible. These changes replace the waiting column with wait_event_type and wait_event.

  • In to_char(), do not count a minus sign (when needed) as part of the field width for time-related fields (Bruce Momjian)

    For example, to_char('-4 years'::interval, 'YY') now returns -04, rather than -4.

  • Make extract() behave more reasonably with infinite inputs (Vitaly Burovoy)

    Historically the extract() function just returned zero given an infinite timestamp, regardless of the given field name. Make it return infinity or -infinity as appropriate when the requested field is one that is monotonically increasing (e.g, year, epoch), or NULL when it is not (e.g., day, hour). Also, throw the expected error for bad field names.

  • Remove PL/pgSQL's "feature" that suppressed the innermost line of CONTEXT for messages emitted by RAISE commands (Pavel Stehule)

    This ancient backwards-compatibility hack was agreed to have outlived its usefulness.

  • Fix the default text search parser to allow leading digits in email and host tokens (Artur Zakirov)

    In most cases this will result in few changes in the parsing of text. But if you have data where such addresses occur frequently, it may be worth rebuilding dependent tsvector columns and indexes so that addresses of this form will be found properly by text searches.

  • Extend contrib/unaccent's standard unaccent.rules file to handle all diacritics known to Unicode, and to expand ligatures correctly (Thomas Munro, Léonard Benedetti)

    The previous version neglected to convert some less-common letters with diacritic marks. Also, ligatures are now expanded into separate letters. Installations that use this rules file may wish to rebuild tsvector columns and indexes that depend on the result.

  • Remove the long-deprecated CREATEUSER/NOCREATEUSER options from CREATE ROLE and allied commands (Tom Lane)

    CREATEUSER actually meant SUPERUSER, for ancient backwards-compatibility reasons. This has been a constant source of confusion for people who (reasonably) expect it to mean CREATEROLE. It has been deprecated for ten years now, so fix the problem by removing it.

  • Treat role names beginning with pg_ as reserved (Stephen Frost)

    User creation of such role names is now disallowed. This prevents conflicts with built-in roles created by initdb.

  • Change a column name in the information_schema.routines view from result_cast_character_set_name to result_cast_char_set_name (Clément Prévost)

    The SQL:2011 standard specifies the longer name, but that appears to be a mistake, because adjacent column names use the shorter style, as do other information_schema views.

  • psql's -c option no longer implies --no-psqlrc (Pavel Stehule, Catalin Iacob)

    Write --no-psqlrc (or its abbreviation -X) explicitly to obtain the old behavior. Scripts so modified will still work with old versions of psql.

  • Improve pg_restore's -t option to match all types of relations, not only plain tables (Craig Ringer)

  • Change the display format used for NextXID in pg_controldata and related places (Joe Conway, Bruce Momjian)

    Display epoch-and-transaction-ID values in the format number:number. The previous format number/number was confusingly similar to that used for LSNs.

  • Update extension functions to be marked parallel-safe where appropriate (Andreas Karlsson)

    Many of the standard extensions have been updated to allow their functions to be executed within parallel query worker processes. These changes will not take effect in databases pg_upgrade'd from prior versions unless you apply ALTER EXTENSION UPDATE to each such extension (in each database of a cluster).

  • Parallel queries (Robert Haas, Amit Kapila, David Rowley, many others)

    With 9.6, PostgreSQL introduces initial support for parallel execution of large queries. Only strictly read-only queries where the driving table is accessed via a sequential scan can be parallelized. Hash joins and nested loops can be performed in parallel, as can aggregation (for supported aggregates). Much remains to be done, but this is already a useful set of features.

    Parallel query execution is not (yet) enabled by default. To allow it, set the new configuration parameter max_parallel_workers_per_gather to a value larger than zero. Additional control over use of parallelism is available through other new configuration parameters force_parallel_mode, parallel_setup_cost, parallel_tuple_cost, and min_parallel_relation_size.

  • Provide infrastructure for marking the parallel-safety status of functions (Robert Haas, Amit Kapila)

  • Allow GIN index builds to make effective use of maintenance_work_mem settings larger than 1 GB (Robert Abraham, Teodor Sigaev)

  • Add pages deleted from a GIN index's pending list to the free space map immediately (Jeff Janes, Teodor Sigaev)

    This reduces bloat if the table is not vacuumed often.

  • Add gin_clean_pending_list() function to allow manual invocation of pending-list cleanup for a GIN index (Jeff Janes)

    Formerly, such cleanup happened only as a byproduct of vacuuming or analyzing the parent table.

  • Improve handling of dead index tuples in GiST indexes (Anastasia Lubennikova)

    Dead index tuples are now marked as such when an index scan notices that the corresponding heap tuple is dead. When inserting tuples, marked-dead tuples will be removed if needed to make space on the page.

  • Add an SP-GiST operator class for type box (Alexander Lebedev)

  • Improve sorting performance by using quicksort, not replacement selection sort, when performing external sort steps (Peter Geoghegan)

    The new approach makes better use of the CPU cache for typical cache sizes and data volumes. Where necessary, the behavior can be adjusted via the new configuration parameter replacement_sort_tuples.

  • Speed up text sorts where the same string occurs multiple times (Peter Geoghegan)

  • Speed up sorting of uuid, bytea, and char(n) fields by using "abbreviated" keys (Peter Geoghegan)

    Support for abbreviated keys has also been added to the non-default operator classes text_pattern_ops, varchar_pattern_ops, and bpchar_pattern_ops. Processing of ordered-set aggregates can also now exploit abbreviated keys.

  • Speed up CREATE INDEX CONCURRENTLY by treating TIDs as 64-bit integers during sorting (Peter Geoghegan)

  • Reduce contention for the ProcArrayLock (Amit Kapila, Robert Haas)

  • Improve performance by moving buffer content locks into the buffer descriptors (Andres Freund, Simon Riggs)

  • Replace shared-buffer header spinlocks with atomic operations to improve scalability (Alexander Korotkov, Andres Freund)

  • Use atomic operations, rather than a spinlock, to protect an LWLock's wait queue (Andres Freund)

  • Partition the shared hash table freelist to reduce contention on multi-CPU-socket servers (Aleksander Alekseev)

  • Reduce interlocking on standby servers during the replay of btree index vacuuming operations (Simon Riggs)

    This change avoids substantial replication delays that sometimes occurred while replaying such operations.

  • Improve ANALYZE's estimates for columns with many nulls (Tomas Vondra, Alex Shulgin)

    Previously ANALYZE tended to underestimate the number of non-NULL distinct values in a column with many NULLs, and was also inaccurate in computing the most-common values.

  • Improve planner's estimate of the number of distinct values in a query result (Tomas Vondra)

  • Use foreign key relationships to infer selectivity for join predicates (Tomas Vondra, David Rowley)

    If a table t has a foreign key restriction, say (a,b) REFERENCES r (x,y), then a WHERE condition such as t.a = r.x AND t.b = r.y cannot select more than one r row per t row. The planner formerly considered these AND conditions to be independent and would often drastically misestimate selectivity as a result. Now it compares the WHERE conditions to applicable foreign key constraints and produces better estimates.

  • Avoid re-vacuuming pages containing only frozen tuples (Masahiko Sawada, Robert Haas, Andres Freund)

    Formerly, anti-wraparound vacuum had to visit every page of a table, even pages where there was nothing to do. Now, pages containing only already-frozen tuples are identified in the table's visibility map, and can be skipped by vacuum even when doing transaction wraparound prevention. This should greatly reduce the cost of maintaining large tables containing mostly-unchanging data.

    If necessary, vacuum can be forced to process all-frozen pages using the new DISABLE_PAGE_SKIPPING option. Normally this should never be needed, but it might help in recovering from visibility-map corruption.

  • Avoid useless heap-truncation attempts during VACUUM (Jeff Janes, Tom Lane)

    This change avoids taking an exclusive table lock in some cases where no truncation is possible. The main benefit comes from avoiding unnecessary query cancellations on standby servers.

  • Allow old MVCC snapshots to be invalidated after a configurable timeout (Kevin Grittner)

    Normally, deleted tuples cannot be physically removed by vacuuming until the last transaction that could "see" them is gone. A transaction that stays open for a long time can thus cause considerable table bloat because space cannot be recycled. This feature allows setting a time-based limit, via the new configuration parameter old_snapshot_threshold, on how long an MVCC snapshot is guaranteed to be valid. After that, dead tuples are candidates for removal. A transaction using an outdated snapshot will get an error if it attempts to read a page that potentially could have contained such data.

  • Ignore GROUP BY columns that are functionally dependent on other columns (David Rowley)

    If a GROUP BY clause includes all columns of a non-deferred primary key, as well as other columns of the same table, those other columns are redundant and can be dropped from the grouping. This saves computation in many common cases.

  • Allow use of an index-only scan on a partial index when the index's WHERE clause references columns that are not indexed (Tomas Vondra, Kyotaro Horiguchi)

    For example, an index defined by CREATE INDEX tidx_partial ON t(b) WHERE a > 0 can now be used for an index-only scan by a query that specifies WHERE a > 0 and does not otherwise use a. Previously this was disallowed because a is not listed as an index column.

  • Perform checkpoint writes in sorted order (Fabien Coelho, Andres Freund)

    Previously, checkpoints wrote out dirty pages in whatever order they happen to appear in shared buffers, which usually is nearly random. That performs poorly, especially on rotating media. This change causes checkpoint-driven writes to be done in order by file and block number, and to be balanced across tablespaces.

  • Where feasible, trigger kernel writeback after a configurable number of writes, to prevent accumulation of dirty data in kernel disk buffers (Fabien Coelho, Andres Freund)

    PostgreSQL writes data to the kernel's disk cache, from where it will be flushed to physical storage in due time. Many operating systems are not smart about managing this and allow large amounts of dirty data to accumulate before deciding to flush it all at once, causing long delays for new I/O requests until the flushing finishes. This change attempts to alleviate this problem by explicitly requesting data flushes after a configurable interval.

    On Linux, sync_file_range() is used for this purpose, and the feature is on by default on Linux because that function has few downsides. This flushing capability is also available on other platforms if they have msync() or posix_fadvise(), but those interfaces have some undesirable side-effects so the feature is disabled by default on non-Linux platforms.

    The new configuration parameters backend_flush_after, bgwriter_flush_after, checkpoint_flush_after, and wal_writer_flush_after control this behavior.

  • Improve aggregate-function performance by sharing calculations across multiple aggregates if they have the same arguments and transition functions (David Rowley)

    For example, SELECT AVG(x), VARIANCE(x) FROM tab can use a single per-row computation for both aggregates.

  • Speed up visibility tests for recently-created tuples by checking the current transaction's snapshot, not pg_clog, to decide if the source transaction should be considered committed (Jeff Janes, Tom Lane)

  • Allow tuple hint bits to be set sooner than before (Andres Freund)

  • Improve performance of short-lived prepared transactions (Stas Kelvich, Simon Riggs, Pavan Deolasee)

    Two-phase commit information is now written only to WAL during PREPARE TRANSACTION, and will be read back from WAL during COMMIT PREPARED if that happens soon thereafter. A separate state file is created only if the pending transaction does not get committed or aborted by the time of the next checkpoint.

  • Improve performance of memory context destruction (Jan Wieck)

  • Improve performance of resource owners with many tracked objects (Aleksander Alekseev)

  • Improve speed of the output functions for timestamp, time, and date data types (David Rowley, Andres Freund)

  • Avoid some unnecessary cancellations of hot-standby queries during replay of actions that take AccessExclusive locks (Jeff Janes)

  • Extend relations multiple blocks at a time when there is contention for the relation's extension lock (Dilip Kumar)

    This improves scalability by decreasing contention.

  • Increase the number of clog buffers for better scalability (Amit Kapila, Andres Freund)

  • Speed up expression evaluation in PL/pgSQL by keeping ParamListInfo entries for simple variables valid at all times (Tom Lane)

  • Avoid reducing the SO_SNDBUF setting below its default on recent Windows versions (Chen Huajun)

  • Disable update_process_title by default on Windows (Takayuki Tsunakawa)

    The overhead of updating the process title is much larger on Windows than most other platforms, and it is also less useful to do it since most Windows users do not have tools that can display process titles.

  • Add pg_stat_progress_vacuum system view to provide progress reporting for VACUUM operations (Amit Langote, Robert Haas, Vinayak Pokale, Rahila Syed)

  • Add pg_control_system(), pg_control_checkpoint(), pg_control_recovery(), and pg_control_init() functions to expose fields of pg_control to SQL (Joe Conway, Michael Paquier)

  • Add pg_config system view (Joe Conway)

    This view exposes the same information available from the pg_config command-line utility, namely assorted compile-time configuration information for PostgreSQL.

  • Add a confirmed_flush_lsn column to the pg_replication_slots system view (Marko Tiikkaja)

  • Add pg_stat_wal_receiver system view to provide information about the state of a hot-standby server's WAL receiver process (Michael Paquier)

  • Add pg_blocking_pids() function to reliably identify which sessions block which others (Tom Lane)

    This function returns an array of the process IDs of any sessions that are blocking the session with the given process ID. Historically users have obtained such information using a self-join on the pg_locks view. However, it is unreasonably tedious to do it that way with any modicum of correctness, and the addition of parallel queries has made the old approach entirely impractical, since locks might be held or awaited by child worker processes rather than the session's main process.

  • Add function pg_current_xlog_flush_location() to expose the current transaction log flush location (Tomas Vondra)

  • Add function pg_notification_queue_usage() to report how full the NOTIFY queue is (Brendan Jurd)

  • Limit the verbosity of memory context statistics dumps (Tom Lane)

    The memory usage dump that is output to the postmaster log during an out-of-memory failure now summarizes statistics when there are a large number of memory contexts, rather than possibly generating a very large report. There is also a "grand total" summary line now.

  • Add a BSD authentication method to allow use of the BSD Authentication service for PostgreSQL client authentication (Marisa Emerson)

    BSD Authentication is currently only available on OpenBSD.

  • When using PAM authentication, provide the client IP address or host name to PAM modules via the PAM_RHOST item (Grzegorz Sampolski)

  • Provide detail in the postmaster log for more types of password authentication failure (Tom Lane)

    All ordinarily-reachable password authentication failure cases should now provide specific DETAIL fields in the log.

  • Support RADIUS passwords up to 128 characters long (Marko Tiikkaja)

  • Add new SSPI authentication parameters compat_realm and upn_username to control whether NetBIOS or Kerberos realm names and user names are used during SSPI authentication (Christian Ullrich)

  • Allow sessions to be terminated automatically if they are in idle-in-transaction state for too long (Vik Fearing)

    This behavior is controlled by the new configuration parameter idle_in_transaction_session_timeout. It can be useful to prevent forgotten transactions from holding locks or preventing vacuum cleanup for too long.

  • Raise the maximum allowed value of checkpoint_timeout to 24 hours (Simon Riggs)

  • Allow effective_io_concurrency to be set per-tablespace to support cases where different tablespaces have different I/O characteristics (Julien Rouhaud)

  • Add log_line_prefix option %n to print the current time in Unix epoch form, with milliseconds (Tomas Vondra, Jeff Davis)

  • Add syslog_sequence_numbers and syslog_split_messages configuration parameters to provide more control over the message format when logging to syslog (Peter Eisentraut)

  • Merge the archive and hot_standby values of the wal_level configuration parameter into a single new value replica (Peter Eisentraut)

    Making a distinction between these settings is no longer useful, and merging them is a step towards a planned future simplification of replication setup. The old names are still accepted but are converted to replica internally.

  • Add configure option --with-systemd to enable calling sd_notify() at server start and stop (Peter Eisentraut)

    This allows the use of systemd service units of type notify, which greatly simplifies the management of PostgreSQL under systemd.

  • Allow the server's SSL key file to have group read access if it is owned by root (Christoph Berg)

    Formerly, we insisted the key file be owned by the user running the PostgreSQL server, but that is inconvenient on some systems (such as Debian) that are configured to manage certificates centrally. Therefore, allow the case where the key file is owned by root and has group read access. It is up to the operating system administrator to ensure that the group does not include any untrusted users.

  • Force backends to exit if the postmaster dies (Rajeev Rastogi, Robert Haas)

    Under normal circumstances the postmaster should always outlive its child processes. If for some reason the postmaster dies, force backend sessions to exit with an error. Formerly, existing backends would continue to run until their clients disconnect, but that is unsafe and inefficient. It also prevents a new postmaster from being started until the last old backend has exited. Backends will detect postmaster death when waiting for client I/O, so the exit will not be instantaneous, but it should happen no later than the end of the current query.

  • Check for serializability conflicts before reporting constraint-violation failures (Thomas Munro)

    When using serializable transaction isolation, it is desirable that any error due to concurrent transactions should manifest as a serialization failure, thereby cueing the application that a retry might succeed. Unfortunately, this does not reliably happen for duplicate-key failures caused by concurrent insertions. This change ensures that such an error will be reported as a serialization error if the application explicitly checked for the presence of a conflicting key (and did not find it) earlier in the transaction.

  • Ensure that invalidation messages are recorded in WAL even when issued by a transaction that has no XID assigned (Andres Freund)

    This fixes some corner cases in which transactions on standby servers failed to notice changes, such as new indexes.

  • Prevent multiple processes from trying to clean a GIN index's pending list concurrently (Teodor Sigaev, Jeff Janes)

    This had been intentionally allowed, but it causes race conditions that can result in vacuum missing index entries it needs to delete.

  • Allow synchronous replication to support multiple simultaneous synchronous standby servers, not just one (Masahiko Sawada, Beena Emerson, Michael Paquier, Fujii Masao, Kyotaro Horiguchi)

    The number of standby servers that must acknowledge a commit before it is considered complete is now configurable as part of the synchronous_standby_names parameter.

  • Add new setting remote_apply for configuration parameter synchronous_commit (Thomas Munro)

    In this mode, the master waits for the transaction to be applied on the standby server, not just written to disk. That means that you can count on a transaction started on the standby to see all commits previously acknowledged by the master.

  • Add a feature to the replication protocol, and a corresponding option to pg_create_physical_replication_slot(), to allow reserving WAL immediately when creating a replication slot (Gurjeet Singh, Michael Paquier)

    This allows the creation of a replication slot to guarantee that all the WAL needed for a base backup will be available.

  • Add a --slot option to pg_basebackup (Peter Eisentraut)

    This lets pg_basebackup use a replication slot defined for WAL streaming. After the base backup completes, selecting the same slot for regular streaming replication allows seamless startup of the new standby server.

  • Extend pg_start_backup() and pg_stop_backup() to support non-exclusive backups (Magnus Hagander)

  • Allow functions that return sets of tuples to return simple NULLs (Andrew Gierth, Tom Lane)

    In the context of SELECT FROM function(...), a function that returned a set of composite values was previously not allowed to return a plain NULL value as part of the set. Now that is allowed and interpreted as a row of NULLs. This avoids corner-case errors with, for example, unnesting an array of composite values.

  • Fully support array subscripts and field selections in the target column list of an INSERT with multiple VALUES rows (Tom Lane)

    Previously, such cases failed if the same target column was mentioned more than once, e.g., INSERT INTO tab (x[1], x[2]) VALUES (...).

  • When appropriate, postpone evaluation of SELECT output expressions until after an ORDER BY sort (Konstantin Knizhnik)

    This change ensures that volatile or expensive functions in the output list are executed in the order suggested by ORDER BY, and that they are not evaluated more times than required when there is a LIMIT clause. Previously, these properties held if the ordering was performed by an index scan or pre-merge-join sort, but not if it was performed by a top-level sort.

  • Widen counters recording the number of tuples processed to 64 bits (Andreas Scherbaum)

    This change allows command tags, e.g. SELECT, to correctly report tuple counts larger than 4 billion. This also applies to PL/pgSQL's GET DIAGNOSTICS ... ROW_COUNT command.

  • Avoid doing encoding conversions by converting through the MULE_INTERNAL encoding (Tom Lane)

    Previously, many conversions for Cyrillic and Central European single-byte encodings were done by converting to a related MULE_INTERNAL coding scheme and then to the destination encoding. Aside from being inefficient, this meant that when the conversion encountered an untranslatable character, the error message would confusingly complain about failure to convert to or from MULE_INTERNAL, rather than the user-visible encoding.

  • Consider performing joins of foreign tables remotely only when the tables will be accessed under the same role ID (Shigeru Hanada, Ashutosh Bapat, Etsuro Fujita)

    Previously, the foreign join pushdown infrastructure left the question of security entirely up to individual foreign data wrappers, but that made it too easy for an FDW to inadvertently create subtle security holes. So, make it the core code's job to determine which role ID will access each table, and do not attempt join pushdown unless the role is the same for all relevant relations.

  • Allow COPY to copy the output of an INSERT/UPDATE/DELETE ... RETURNING query (Marko Tiikkaja)

    Previously, an intermediate CTE had to be written to get this result.

  • Introduce ALTER object DEPENDS ON EXTENSION (Abhijit Menon-Sen)

    This command allows a database object to be marked as depending on an extension, so that it will be dropped automatically if the extension is dropped (without needing CASCADE). However, the object is not part of the extension, and thus will be dumped separately by pg_dump.

  • Make ALTER object SET SCHEMA do nothing when the object is already in the requested schema, rather than throwing an error as it historically has for most object types (Marti Raudsepp)

  • Add options to ALTER OPERATOR to allow changing the selectivity functions associated with an existing operator (Yury Zhuravlev)

  • Add an IF NOT EXISTS option to ALTER TABLE ADD COLUMN (Fabrízio de Royes Mello)

  • Reduce the lock strength needed by ALTER TABLE when setting fillfactor and autovacuum-related relation options (Fabrízio de Royes Mello, Simon Riggs)

  • Introduce CREATE ACCESS METHOD to allow extensions to create index access methods (Alexander Korotkov, Petr Jelínek)

  • Add a CASCADE option to CREATE EXTENSION to automatically create any extensions the requested one depends on (Petr Jelínek)

  • Make CREATE TABLE ... LIKE include an OID column if any source table has one (Bruce Momjian)

  • If a CHECK constraint is declared NOT VALID in a table creation command, automatically mark it as valid (Amit Langote, Amul Sul)

    This is safe because the table has no existing rows. This matches the longstanding behavior of FOREIGN KEY constraints.

  • Fix DROP OPERATOR to clear pg_operator.oprcom and pg_operator.oprnegate links to the dropped operator (Roma Sokolov)

    Formerly such links were left as-is, which could pose a problem in the somewhat unlikely event that the dropped operator's OID was reused for another operator.

  • Do not show the same subplan twice in EXPLAIN output (Tom Lane)

    In certain cases, typically involving SubPlan nodes in index conditions, EXPLAIN would print data for the same subplan twice.

  • Disallow creation of indexes on system columns, except for OID columns (David Rowley)

    Such indexes were never considered supported, and would very possibly misbehave since the system might change the system-column fields of a tuple without updating indexes. However, previously there were no error checks to prevent them from being created.

  • Use the privilege system to manage access to sensitive functions (Stephen Frost)

    Formerly, many security-sensitive functions contained hard-wired checks that would throw an error if they were called by a non-superuser. This forced the use of superuser roles for some relatively pedestrian tasks. The hard-wired error checks are now gone in favor of making initdb revoke the default public EXECUTE privilege on these functions. This allows installations to choose to grant usage of such functions to trusted roles that do not need all superuser privileges.

  • Create some built-in roles that can be used to grant access to what were previously superuser-only functions (Stephen Frost)

    Currently the only such role is pg_signal_backend, but more are expected to be added in future.

  • Improve full-text search to support searching for phrases, that is, lexemes appearing adjacent to each other in a specific order, or with a specified distance between them (Teodor Sigaev, Oleg Bartunov, Dmitry Ivanov)

    A phrase-search query can be specified in tsquery input using the new operators <-> and <N>. The former means that the lexemes before and after it must appear adjacent to each other in that order. The latter means they must be exactly N lexemes apart.

  • Allow omitting one or both boundaries in an array slice specifier, e.g. array_col[3:] (Yury Zhuravlev)

    Omitted boundaries are taken as the upper or lower limit of the corresponding array subscript. This allows simpler specification for many common use-cases.

  • Be more careful about out-of-range dates and timestamps (Vitaly Burovoy)

    This change prevents unexpected out-of-range errors for timestamp with time zone values very close to the implementation limits. Previously, the "same" value might be accepted or not depending on the timezone setting, meaning that a dump and reload could fail on a value that had been accepted when presented. Now the limits are enforced according to the equivalent UTC time, not local time, so as to be independent of timezone.

    Also, PostgreSQL is now more careful to detect overflow in operations that compute new date or timestamp values, such as date + integer.

  • For geometric data types, make sure infinity and NaN component values are treated consistently during input and output (Tom Lane)

    Such values will now always print the same as they would in a simple float8 column, and be accepted the same way on input. Previously the behavior was platform-dependent.

  • Upgrade the ispell dictionary type to handle modern Hunspell files and support more languages (Artur Zakirov)

  • Implement look-behind constraints in regular expressions (Tom Lane)

    A look-behind constraint is like a lookahead constraint in that it consumes no text; but it checks for existence (or nonexistence) of a match ending at the current point in the string, rather than one starting at the current point. Similar features exist in many other regular-expression engines.

  • In regular expressions, if an apparent three-digit octal escape \nnn would exceed 377 (255 decimal), assume it is a two-digit octal escape instead (Tom Lane)

    This makes the behavior match current Tcl releases.

  • Add transaction ID operators xid <> xid and xid <> int4, for consistency with the corresponding equality operators (Michael Paquier)

  • Add jsonb_insert() function to insert a new element into a jsonb array, or a not-previously-existing key into a jsonb object (Dmitry Dolgov)

  • Improve the accuracy of the ln(), log(), exp(), and pow() functions for type numeric (Dean Rasheed)

  • Add a scale(numeric) function to extract the display scale of a numeric value (Marko Tiikkaja)

  • Add trigonometric functions that work in degrees (Dean Rasheed)

    For example, sind() measures its argument in degrees, whereas sin() measures in radians. These functions go to some lengths to deliver exact results for values where an exact result can be expected, for instance sind(30) = 0.5.

  • Ensure that trigonometric functions handle infinity and NaN inputs per the POSIX standard (Dean Rasheed)

    The POSIX standard says that these functions should return NaN for NaN input, and should throw an error for out-of-range inputs including infinity. Previously our behavior varied across platforms.

  • Make to_timestamp(float8) convert float infinity to timestamp infinity (Vitaly Burovoy)

    Formerly it just failed on an infinite input.

  • Add new functions for tsvector data (Stas Kelvich)

    The new functions are ts_delete(), ts_filter(), unnest(), tsvector_to_array(), array_to_tsvector(), and a variant of setweight() that sets the weight only for specified lexeme(s).

  • Allow ts_stat() and tsvector_update_trigger() to operate on values that are of types binary-compatible with the expected argument type, not just exactly that type; for example allow citext where text is expected (Teodor Sigaev)

  • Add variadic functions num_nulls() and num_nonnulls() that count the number of their arguments that are null or non-null (Marko Tiikkaja)

    An example usage is CHECK(num_nonnulls(a,b,c) = 1) which asserts that exactly one of a,b,c is not NULL. These functions can also be used to count the number of null or nonnull elements in an array.

  • Add function parse_ident() to split a qualified, possibly quoted SQL identifier into its parts (Pavel Stehule)

  • In to_number(), interpret a V format code as dividing by 10 to the power of the number of digits following V (Bruce Momjian)

    This makes it operate in an inverse fashion to to_char().

  • Make the to_reg*() functions accept type text not cstring (Petr Korobeinikov)

    This avoids the need to write an explicit cast in most cases where the argument is not a simple literal constant.

  • Add pg_size_bytes() function to convert human-readable size strings to numbers (Pavel Stehule, Vitaly Burovoy, Dean Rasheed)

    This function converts strings like those produced by pg_size_pretty() into bytes. An example usage is SELECT oid::regclass FROM pg_class WHERE pg_total_relation_size(oid) > pg_size_bytes('10 GB').

  • In pg_size_pretty(), format negative numbers similarly to positive ones (Adrian Vondendriesch)

    Previously, negative numbers were never abbreviated, just printed in bytes.

  • Add an optional missing_ok argument to the current_setting() function (David Christensen)

    This allows avoiding an error for an unrecognized parameter name, instead returning a NULL.

  • Change various catalog-inspection functions to return NULL for invalid input (Michael Paquier)

    pg_get_viewdef() now returns NULL if given an invalid view OID, and several similar functions likewise return NULL for bad input. Previously, such cases usually led to "cache lookup failed" errors, which are not meant to occur in user-facing cases.

  • Fix pg_replication_origin_xact_reset() to not have any arguments (Fujii Masao)

    The documentation said that it has no arguments, and the C code did not expect any arguments, but the entry in pg_proc mistakenly specified two arguments.

  • In PL/pgSQL, detect mismatched CONTINUE and EXIT statements while compiling a function, rather than at execution time (Jim Nasby)

  • Extend PL/Python's error-reporting and message-reporting functions to allow specifying additional message fields besides the primary error message (Pavel Stehule)

  • Allow PL/Python functions to call themselves recursively via SPI, and fix the behavior when multiple set-returning PL/Python functions are called within one query (Alexey Grishchenko, Tom Lane)

  • Fix session-lifespan memory leaks in PL/Python (Heikki Linnakangas, Haribabu Kommi, Tom Lane)

  • Modernize PL/Tcl to use Tcl's "object" APIs instead of simple strings (Jim Nasby, Karl Lehenbauer)

    This can improve performance substantially in some cases. Note that PL/Tcl now requires Tcl 8.4 or later.

  • In PL/Tcl, make database-reported errors return additional information in Tcl's errorCode global variable (Jim Nasby, Tom Lane)

    This feature follows the Tcl convention for returning auxiliary data about an error.

  • Fix PL/Tcl to perform encoding conversion between the database encoding and UTF-8, which is what Tcl expects (Tom Lane)

    Previously, strings were passed through without conversion, leading to misbehavior with non-ASCII characters when the database encoding was not UTF-8.

  • Add a nonlocalized version of the severity field in error and notice messages (Tom Lane)

    This change allows client code to determine severity of an error or notice without having to worry about localized variants of the severity strings.

  • Introduce a feature in libpq whereby the CONTEXT field of messages can be suppressed, either always or only for non-error messages (Pavel Stehule)

    The default behavior of PQerrorMessage() is now to print CONTEXT only for errors. The new function PQsetErrorContextVisibility() can be used to adjust this.

  • Add support in libpq for regenerating an error message with a different verbosity level (Alex Shulgin)

    This is done with the new function PQresultVerboseErrorMessage(). This supports psql's new \errverbose feature, and may be useful for other clients as well.

  • Improve libpq's PQhost() function to return useful data for default Unix-socket connections (Tom Lane)

    Previously it would return NULL if no explicit host specification had been given; now it returns the default socket directory path.

  • Fix ecpg's lexer to handle line breaks within comments starting on preprocessor directive lines (Michael Meskes)

  • Add a --strict-names option to pg_dump and pg_restore (Pavel Stehule)

    This option causes the program to complain if there is no match for a -t or -n option, rather than silently doing nothing.

  • In pg_dump, dump locally-made changes of privilege assignments for system objects (Stephen Frost)

    While it has always been possible for a superuser to change the privilege assignments for built-in or extension-created objects, such changes were formerly lost in a dump and reload. Now, pg_dump recognizes and dumps such changes. (This works only when dumping from a 9.6 or later server, however.)

  • Allow pg_dump to dump non-extension-owned objects that are within an extension-owned schema (Martín Marqués)

    Previously such objects were ignored because they were mistakenly assumed to belong to the extension owning their schema.

  • In pg_dump output, include the table name in object tags for object types that are only uniquely named per-table (for example, triggers) (Peter Eisentraut)

  • Support multiple -c and -f command-line options (Pavel Stehule, Catalin Iacob)

    The specified operations are carried out in the order in which the options are given, and then psql terminates.

  • Add a \crosstabview command that prints the results of a query in a cross-tabulated display (Daniel Vérité)

    In the crosstab display, data values from one query result column are placed in a grid whose column and row headers come from other query result columns.

  • Add an \errverbose command that shows the last server error at full verbosity (Alex Shulgin)

    This is useful after getting an unexpected error — you no longer need to adjust the VERBOSITY variable and recreate the failure in order to see error fields that are not shown by default.

  • Add \ev and \sv commands for editing and showing view definitions (Petr Korobeinikov)

    These are parallel to the existing \ef and \sf commands for functions.

  • Add a \gexec command that executes a query and re-submits the result(s) as new queries (Corey Huinker)

  • Allow \pset C string to set the table title, for consistency with \C string (Bruce Momjian)

  • In \pset expanded auto mode, do not use expanded format for query results with only one column (Andreas Karlsson, Robert Haas)

  • Improve the headers output by the \watch command (Michael Paquier, Tom Lane)

    Include the \pset title string if one has been set, and shorten the prefabricated part of the header to be timestamp (every Ns). Also, the timestamp format now obeys psql's locale environment.

  • Improve tab-completion logic to consider the entire input query, not only the current line (Tom Lane)

    Previously, breaking a command into multiple lines defeated any tab completion rules that needed to see words on earlier lines.

  • Numerous minor improvements in tab-completion behavior (Peter Eisentraut, Vik Fearing, Kevin Grittner, Kyotaro Horiguchi, Jeff Janes, Andreas Karlsson, Fujii Masao, Thomas Munro, Masahiko Sawada, Pavel Stehule)

  • Add a PROMPT option %p to insert the process ID of the connected backend (Julien Rouhaud)

  • Introduce a feature whereby the CONTEXT field of messages can be suppressed, either always or only for non-error messages (Pavel Stehule)

    Printing CONTEXT only for errors is now the default behavior. This can be changed by setting the special variable SHOW_CONTEXT.

  • Make \df+ show function access privileges and parallel-safety attributes (Michael Paquier)

  • SQL commands in pgbench scripts are now ended by semicolons, not newlines (Kyotaro Horiguchi, Tom Lane)

    This change allows SQL commands in scripts to span multiple lines. Existing custom scripts will need to be modified to add a semicolon at the end of each line that does not have one already. (Doing so does not break the script for use with older versions of pgbench.)

  • Support floating-point arithmetic, as well as some built-in functions, in expressions in backslash commands (Fabien Coelho)

  • Replace \setrandom with built-in functions (Fabien Coelho)

    The new built-in functions include random(), random_exponential(), and random_gaussian(), which perform the same work as \setrandom, but are easier to use since they can be embedded in larger expressions. Since these additions have made \setrandom obsolete, remove it.

  • Allow invocation of multiple copies of the built-in scripts, not only custom scripts (Fabien Coelho)

    This is done with the new -b switch, which works similarly to -f for custom scripts.

  • Allow changing the selection probabilities (weights) for scripts (Fabien Coelho)

    When multiple scripts are specified, each pgbench transaction randomly chooses one to execute. Formerly this was always done with uniform probability, but now different selection probabilities can be specified for different scripts.

  • Collect statistics for each script in a multi-script run (Fabien Coelho)

    This feature adds an intermediate level of detail to existing global and per-command statistics printouts.

  • Add a --progress-timestamp option to report progress with Unix epoch timestamps, instead of time since the run started (Fabien Coelho)

  • Allow the number of client connections (-c) to not be an exact multiple of the number of threads (-j) (Fabien Coelho)

  • When the -T option is used, stop promptly at the end of the specified time (Fabien Coelho)

    Previously, specifying a low transaction rate could cause pgbench to wait significantly longer than specified.

  • Improve error reporting during initdb's post-bootstrap phase (Tom Lane)

    Previously, an error here led to reporting the entire input file as the "failing query"; now just the current query is reported. To get the desired behavior, queries in initdb's input files must be separated by blank lines.

  • Speed up initdb by using just one standalone-backend session for all the post-bootstrap steps (Tom Lane)

  • Improve pg_rewind so that it can work when the target timeline changes (Alexander Korotkov)

    This allows, for example, rewinding a promoted standby back to some state of the old master's timeline.

  • Remove obsolete heap_formtuple/heap_modifytuple/heap_deformtuple functions (Peter Geoghegan)

  • Add macros to make AllocSetContextCreate() calls simpler and safer (Tom Lane)

    Writing out the individual sizing parameters for a memory context is now deprecated in favor of using one of the new macros ALLOCSET_DEFAULT_SIZES, ALLOCSET_SMALL_SIZES, or ALLOCSET_START_SMALL_SIZES. Existing code continues to work, however.

  • Unconditionally use static inline functions in header files (Andres Freund)

    This may result in warnings and/or wasted code space with very old compilers, but the notational improvement seems worth it.

  • Improve TAP testing infrastructure (Michael Paquier, Craig Ringer, Álvaro Herrera, Stephen Frost)

    Notably, it is now possible to test recovery scenarios using this infrastructure.

  • Make trace_lwlocks identify individual locks by name (Robert Haas)

  • Improve psql's tab-completion code infrastructure (Thomas Munro, Michael Paquier)

    Tab-completion rules are now considerably easier to write, and more compact.

  • Nail the pg_shseclabel system catalog into cache, so that it is available for access during connection authentication (Adam Brightwell)

    The core code does not use this catalog for authentication, but extensions might wish to consult it.

  • Restructure index access method API to hide most of it at the C level (Alexander Korotkov, Andrew Gierth)

    This change modernizes the index AM API to look more like the designs we have adopted for foreign data wrappers and tablesample handlers. This simplifies the C code and makes it much more practical to define index access methods in installable extensions. A consequence is that most of the columns of the pg_am system catalog have disappeared. New inspection functions have been added to allow SQL queries to determine index AM properties that used to be discoverable from pg_am.

  • Add pg_init_privs system catalog to hold original privileges of initdb-created and extension-created objects (Stephen Frost)

    This infrastructure allows pg_dump to dump changes that an installation may have made in privileges attached to system objects. Formerly, such changes would be lost in a dump and reload, but now they are preserved.

  • Change the way that extensions allocate custom LWLocks (Amit Kapila, Robert Haas)

    The RequestAddinLWLocks() function is removed, and replaced by RequestNamedLWLockTranche(). This allows better identification of custom LWLocks, and is less error-prone.

  • Improve the isolation tester to allow multiple sessions to wait concurrently, allowing testing of deadlock scenarios (Robert Haas)

  • Introduce extensible node types (KaiGai Kohei)

    This change allows FDWs or custom scan providers to store data in a plan tree in a more convenient format than was previously possible.

  • Make the planner deal with post-scan/join query steps by generating and comparing Paths, replacing a lot of ad-hoc logic (Tom Lane)

    This change provides only marginal user-visible improvements today, but it enables future work on a lot of upper-planner improvements that were impractical to tackle using the old code structure.

  • Support partial aggregation (David Rowley, Simon Riggs)

    This change allows the computation of an aggregate function to be split into separate parts, for example so that parallel worker processes can cooperate on computing an aggregate. In future it might allow aggregation across local and remote data to occur partially on the remote end.

  • Add a generic command progress reporting facility (Vinayak Pokale, Rahila Syed, Amit Langote, Robert Haas)

  • Separate out psql's flex lexer to make it usable by other client programs (Tom Lane, Kyotaro Horiguchi)

    This eliminates code duplication for programs that need to be able to parse SQL commands well enough to identify command boundaries. Doing that in full generality is more painful than one could wish, and up to now only psql has really gotten it right among our supported client programs.

    A new source-code subdirectory src/fe_utils/ has been created to hold this and other code that is shared across our client programs. Formerly such sharing was accomplished by symbolic linking or copying source files at build time, which was ugly and required duplicate compilation.

  • Introduce WaitEventSet API to allow efficient waiting for event sets that usually do not change from one wait to the next (Andres Freund, Amit Kapila)

  • Add a generic interface for writing WAL records (Alexander Korotkov, Petr Jelínek, Markus Nullmeier)

    This change allows extensions to write WAL records for changes to pages using a standard layout. The problem of needing to replay WAL without access to the extension is solved by having generic replay code. This allows extensions to implement, for example, index access methods and have WAL support for them.

  • Support generic WAL messages for logical decoding (Petr Jelínek, Andres Freund)

    This feature allows extensions to insert data into the WAL stream that can be read by logical-decoding plugins, but is not connected to physical data restoration.

  • Allow SP-GiST operator classes to store an arbitrary "traversal value" while descending the index (Alexander Lebedev, Teodor Sigaev)

    This is somewhat like the "reconstructed value", but it could be any arbitrary chunk of data, not necessarily of the same data type as the indexed column.

  • Introduce a LOG_SERVER_ONLY message level for ereport() (David Steele)

    This level acts like LOG except that the message is never sent to the client. It is meant for use in auditing and similar applications.

  • Provide a Makefile target to build all generated headers (Michael Paquier, Tom Lane)

    submake-generated-headers can now be invoked to ensure that generated backend header files are up-to-date. This is useful in subdirectories that might be built "standalone".

  • Support OpenSSL 1.1.0 (Andreas Karlsson, Heikki Linnakangas)

  • Add configuration parameter auto_explain.sample_rate to allow contrib/auto_explain to capture just a configurable fraction of all queries (Craig Ringer, Julien Rouhaud)

    This allows reduction of overhead for heavy query traffic, while still getting useful information on average.

  • Add contrib/bloom module that implements an index access method based on Bloom filtering (Teodor Sigaev, Alexander Korotkov)

    This is primarily a proof-of-concept for non-core index access methods, but it could be useful in its own right for queries that search many columns.

  • In contrib/cube, introduce distance operators for cubes, and support kNN-style searches in GiST indexes on cube columns (Stas Kelvich)

  • Make contrib/hstore's hstore_to_jsonb_loose() and hstore_to_json_loose() functions agree on what is a number (Tom Lane)

    Previously, hstore_to_jsonb_loose() would convert numeric-looking strings to JSON numbers, rather than strings, even if they did not exactly match the JSON syntax specification for numbers. This was inconsistent with hstore_to_json_loose(), so tighten the test to match the JSON syntax.

  • Add selectivity estimation functions for contrib/intarray operators to improve plans for queries using those operators (Yury Zhuravlev, Alexander Korotkov)

  • Make contrib/pageinspect's heap_page_items() function show the raw data in each tuple, and add new functions tuple_data_split() and heap_page_item_attrs() for inspection of individual tuple fields (Nikolay Shaplov)

  • Add an optional S2K iteration count parameter to contrib/pgcrypto's pgp_sym_encrypt() function (Jeff Janes)

  • Add support for "word similarity" to contrib/pg_trgm (Alexander Korotkov, Artur Zakirov)

    These functions and operators measure the similarity between one string and the most similar single word of another string.

  • Add configuration parameter pg_trgm.similarity_threshold for contrib/pg_trgm's similarity threshold (Artur Zakirov)

    This threshold has always been configurable, but formerly it was controlled by special-purpose functions set_limit() and show_limit(). Those are now deprecated.

  • Improve contrib/pg_trgm's GIN operator class to speed up index searches in which both common and rare keys appear (Jeff Janes)

  • Improve performance of similarity searches in contrib/pg_trgm GIN indexes (Christophe Fornaroli)

  • Add contrib/pg_visibility module to allow examining table visibility maps (Robert Haas)

  • Add ssl_extension_info() function to contrib/sslinfo, to print information about SSL extensions present in the X509 certificate used for the current connection (Dmitry Voronin)

  • Allow extension-provided operators and functions to be sent for remote execution, if the extension is whitelisted in the foreign server's options (Paul Ramsey)

    Users can enable this feature when the extension is known to exist in a compatible version in the remote database. It allows more efficient execution of queries involving extension operators.

  • Consider performing sorts on the remote server (Ashutosh Bapat)

  • Consider performing joins on the remote server (Shigeru Hanada, Ashutosh Bapat)

  • When feasible, perform UPDATE or DELETE entirely on the remote server (Etsuro Fujita)

    Formerly, remote updates involved sending a SELECT FOR UPDATE command and then updating or deleting the selected rows one-by-one. While that is still necessary if the operation requires any local processing, it can now be done remotely if all elements of the query are safe to send to the remote server.

  • Allow the fetch size to be set as a server or table option (Corey Huinker)

    Formerly, postgres_fdw always fetched 100 rows at a time from remote queries; now that behavior is configurable.

  • Use a single foreign-server connection for local user IDs that all map to the same remote user (Ashutosh Bapat)

  • Transmit query cancellation requests to the remote server (Michael Paquier, Etsuro Fujita)

    Previously, a local query cancellation request did not cause an already-sent remote query to terminate early.

• ⇑ Upgrade to 9.6.1 released on 2016-10-27 - docs

  • Fix WAL-logging of truncation of relation free space maps and visibility maps (Pavan Deolasee, Heikki Linnakangas)

    It was possible for these files to not be correctly restored during crash recovery, or to be written incorrectly on a standby server. Bogus entries in a free space map could lead to attempts to access pages that have been truncated away from the relation itself, typically producing errors like "could not read block XXX: read only 0 of 8192 bytes". Checksum failures in the visibility map are also possible, if checksumming is enabled.

    Procedures for determining whether there is a problem and repairing it if so are discussed at https://wiki.postgresql.org/wiki/Free_Space_Map_Problems.

  • Fix possible data corruption when pg_upgrade rewrites a relation visibility map into 9.6 format (Tom Lane)

    On big-endian machines, bytes of the new visibility map were written in the wrong order, leading to a completely incorrect map. On Windows, the old map was read using text mode, leading to incorrect results if the map happened to contain consecutive bytes that matched a carriage return/line feed sequence. The latter error would almost always lead to a pg_upgrade failure due to the map file appearing to be the wrong length.

    If you are using a big-endian machine (many non-Intel architectures are big-endian) and have used pg_upgrade to upgrade from a pre-9.6 release, you should assume that all visibility maps are incorrect and need to be regenerated. It is sufficient to truncate each relation's visibility map with contrib/pg_visibility's pg_truncate_visibility_map() function. For more information see https://wiki.postgresql.org/wiki/Visibility_Map_Problems.

  • Don't throw serialization errors for self-conflicting insertions in INSERT ... ON CONFLICT (Thomas Munro, Peter Geoghegan)

  • Fix use-after-free hazard in execution of aggregate functions using DISTINCT (Peter Geoghegan)

    This could lead to a crash or incorrect query results.

  • Fix incorrect handling of polymorphic aggregates used as window functions (Tom Lane)

    The aggregate's transition function was told that its first argument and result were of the aggregate's output type, rather than the state type. This led to errors or crashes with polymorphic transition functions.

  • Fix COPY with a column name list from a table that has row-level security enabled (Adam Brightwell)

  • Fix EXPLAIN to emit valid XML when track_io_timing is on (Markus Winand)

    Previously the XML output-format option produced syntactically invalid tags such as <I/O-Read-Time>. That is now rendered as <I-O-Read-Time>.

  • Fix statistics update for TRUNCATE in a prepared transaction (Stas Kelvich)

  • Fix bugs in merging inherited CHECK constraints while creating or altering a table (Tom Lane, Amit Langote)

    Allow identical CHECK constraints to be added to a parent and child table in either order. Prevent merging of a valid constraint from the parent table with a NOT VALID constraint on the child. Likewise, prevent merging of a NO INHERIT child constraint with an inherited constraint.

  • Show a sensible value in pg_settings.unit for min_wal_size and max_wal_size (Tom Lane)

  • Fix replacement of array elements in jsonb_set() (Tom Lane)

    If the target is an existing JSON array element, it got deleted instead of being replaced with a new value.

  • Avoid very-low-probability data corruption due to testing tuple visibility without holding buffer lock (Thomas Munro, Peter Geoghegan, Tom Lane)

  • Preserve commit timestamps across server restart (Julien Rouhaud, Craig Ringer)

    With track_commit_timestamp turned on, old commit timestamps became inaccessible after a clean server restart.

  • Fix logical WAL decoding to work properly when a subtransaction's WAL output is large enough to spill to disk (Andres Freund)

  • Fix dangling-pointer problem in logical WAL decoding (Stas Kelvich)

  • Round shared-memory allocation request to a multiple of the actual huge page size when attempting to use huge pages on Linux (Tom Lane)

    This avoids possible failures during munmap() on systems with atypical default huge page sizes. Except in crash-recovery cases, there were no ill effects other than a log message.

  • Don't try to share SSL contexts across multiple connections in libpq (Heikki Linnakangas)

    This led to assorted corner-case bugs, particularly when trying to use different SSL parameters for different connections.

  • Avoid corner-case memory leak in libpq (Tom Lane)

    The reported problem involved leaking an error report during PQreset(), but there might be related cases.

  • In pg_upgrade, check library loadability in name order (Tom Lane)

    This is a workaround to deal with cross-extension dependencies from language transform modules to their base language and data type modules.

  • Fix pg_upgrade to work correctly for extensions containing index access methods (Tom Lane)

    To allow this, the server has been extended to support ALTER EXTENSION ADD/DROP ACCESS METHOD. That functionality should have been included in the original patch to support dynamic creation of access methods, but it was overlooked.

  • Improve error reporting in pg_upgrade's file copying/linking/rewriting steps (Tom Lane, Álvaro Herrera)

  • Fix pg_dump to work against pre-7.4 servers (Amit Langote, Tom Lane)

  • Disallow specifying both --source-server and --source-target options to pg_rewind (Michael Banck)

  • Make pg_rewind turn off synchronous_commit in its session on the source server (Michael Banck, Michael Paquier)

    This allows pg_rewind to work even when the source server is using synchronous replication that is not working for some reason.

  • In pg_xlogdump, retry opening new WAL segments when using --follow option (Magnus Hagander)

    This allows for a possible delay in the server's creation of the next segment.

  • Fix contrib/pg_visibility to report the correct TID for a corrupt tuple that has been the subject of a rolled-back update (Tom Lane)

  • Fix makefile dependencies so that parallel make of PL/Python by itself will succeed reliably (Pavel Raiskup)

  • Update time zone data files to tzdata release 2016h for DST law changes in Palestine and Turkey, plus historical corrections for Turkey and some regions of Russia. Switch to numeric abbreviations for some time zones in Antarctica, the former Soviet Union, and Sri Lanka.

    The IANA time zone database previously provided textual abbreviations for all time zones, sometimes making up abbreviations that have little or no currency among the local population. They are in process of reversing that policy in favor of using numeric UTC offsets in zones where there is no evidence of real-world use of an English abbreviation. At least for the time being, PostgreSQL will continue to accept such removed abbreviations for timestamp input. But they will not be shown in the pg_timezone_names view nor used for output.

    In this update, AMT is no longer shown as being in use to mean Armenia Time. Therefore, we have changed the Default abbreviation set to interpret it as Amazon Time, thus UTC-4 not UTC+4.

• ⇑ Upgrade to 9.6.2 released on 2017-02-09 - docs

  • Fix a race condition that could cause indexes built with CREATE INDEX CONCURRENTLY to be corrupt (Pavan Deolasee, Tom Lane)

    If CREATE INDEX CONCURRENTLY was used to build an index that depends on a column not previously indexed, then rows updated by transactions that ran concurrently with the CREATE INDEX command could have received incorrect index entries. If you suspect this may have happened, the most reliable solution is to rebuild affected indexes after installing this update.

  • Ensure that the special snapshot used for catalog scans is not invalidated by premature data pruning (Tom Lane)

    Backends failed to account for this snapshot when advertising their oldest xmin, potentially allowing concurrent vacuuming operations to remove data that was still needed. This led to transient failures along the lines of "cache lookup failed for relation 1255".

  • Fix incorrect WAL logging for BRIN indexes (Kuntal Ghosh)

    The WAL record emitted for a BRIN "revmap" page when moving an index tuple to a different page was incorrect. Replay would make the related portion of the index useless, forcing it to be recomputed.

  • Unconditionally WAL-log creation of the "init fork" for an unlogged table (Michael Paquier)

    Previously, this was skipped when wal_level = minimal, but actually it's necessary even in that case to ensure that the unlogged table is properly reset to empty after a crash.

  • If the stats collector dies during hot standby, restart it (Takayuki Tsunakawa)

  • Ensure that hot standby feedback works correctly when it's enabled at standby server start (Ants Aasma, Craig Ringer)

  • Check for interrupts while hot standby is waiting for a conflicting query (Simon Riggs)

  • Avoid constantly respawning the autovacuum launcher in a corner case (Amit Khandekar)

    This fix avoids problems when autovacuum is nominally off and there are some tables that require freezing, but all such tables are already being processed by autovacuum workers.

  • Disallow setting the num_sync field to zero in synchronous_standby_names (Fujii Masao)

    The correct way to disable synchronous standby is to set the whole value to an empty string.

  • Don't count background worker processes against a user's connection limit (David Rowley)

  • Fix check for when an extension member object can be dropped (Tom Lane)

    Extension upgrade scripts should be able to drop member objects, but this was disallowed for serial-column sequences, and possibly other cases.

  • Fix tracking of initial privileges for extension member objects so that it works correctly with ALTER EXTENSION ... ADD/DROP (Stephen Frost)

    An object's current privileges at the time it is added to the extension will now be considered its default privileges; only later changes in its privileges will be dumped by subsequent pg_dump runs.

  • Make sure ALTER TABLE preserves index tablespace assignments when rebuilding indexes (Tom Lane, Michael Paquier)

    Previously, non-default settings of default_tablespace could result in broken indexes.

  • Fix incorrect updating of trigger function properties when changing a foreign-key constraint's deferrability properties with ALTER TABLE ... ALTER CONSTRAINT (Tom Lane)

    This led to odd failures during subsequent exercise of the foreign key, as the triggers were fired at the wrong times.

  • Prevent dropping a foreign-key constraint if there are pending trigger events for the referenced relation (Tom Lane)

    This avoids "could not find trigger NNN" or "relation NNN has no triggers" errors.

  • Fix ALTER TABLE ... SET DATA TYPE ... USING when child table has different column ordering than the parent (Álvaro Herrera)

    Failure to adjust the column numbering in the USING expression led to errors, typically "attribute N has wrong type".

  • Fix processing of OID column when a table with OIDs is associated to a parent with OIDs via ALTER TABLE ... INHERIT (Amit Langote)

    The OID column should be treated the same as regular user columns in this case, but it wasn't, leading to odd behavior in later inheritance changes.

  • Ensure that CREATE TABLE ... LIKE ... WITH OIDS creates a table with OIDs, whether or not the LIKE-referenced table(s) have OIDs (Tom Lane)

  • Fix CREATE OR REPLACE VIEW to update the view query before attempting to apply the new view options (Dean Rasheed)

    Previously the command would fail if the new options were inconsistent with the old view definition.

  • Report correct object identity during ALTER TEXT SEARCH CONFIGURATION (Artur Zakirov)

    The wrong catalog OID was reported to extensions such as logical decoding.

  • Fix commit timestamp mechanism to not fail when queried about the special XIDs FrozenTransactionId and BootstrapTransactionId (Craig Ringer)

  • Fix incorrect use of view reloptions as regular table reloptions (Tom Lane)

    The symptom was spurious "ON CONFLICT is not supported on table ... used as a catalog table" errors when the target of INSERT ... ON CONFLICT is a view with cascade option.

  • Fix incorrect "target lists can have at most N entries" complaint when using ON CONFLICT with wide tables (Tom Lane)

  • Fix spurious "query provides a value for a dropped column" errors during INSERT or UPDATE on a table with a dropped column (Tom Lane)

  • Prevent multicolumn expansion of foo.* in an UPDATE source expression (Tom Lane)

    This led to "UPDATE target count mismatch --- internal error". Now the syntax is understood as a whole-row variable, as it would be in other contexts.

  • Ensure that column typmods are determined accurately for multi-row VALUES constructs (Tom Lane)

    This fixes problems occurring when the first value in a column has a determinable typmod (e.g., length for a varchar value) but later values don't share the same limit.

  • Throw error for an unfinished Unicode surrogate pair at the end of a Unicode string (Tom Lane)

    Normally, a Unicode surrogate leading character must be followed by a Unicode surrogate trailing character, but the check for this was missed if the leading character was the last character in a Unicode string literal (U&'...') or Unicode identifier (U&"...").

  • Fix execution of DISTINCT and ordered aggregates when multiple such aggregates are able to share the same transition state (Heikki Linnakangas)

  • Fix implementation of phrase search operators in tsquery (Tom Lane)

    Remove incorrect, and inconsistently-applied, rewrite rules that tried to transform away AND/OR/NOT operators appearing below a PHRASE operator; instead upgrade the execution engine to handle such cases correctly. This fixes assorted strange behavior and possible crashes for text search queries containing such combinations. Also fix nested PHRASE operators to work sanely in combinations other than simple left-deep trees, correct the behavior when removing stopwords from a phrase search clause, and make sure that index searches behave consistently with simple sequential-scan application of such queries.

  • Ensure that a purely negative text search query, such as !foo, matches empty tsvectors (Tom Dunstan)

    Such matches were found by GIN index searches, but not by sequential scans or GiST index searches.

  • Prevent crash when ts_rewrite() replaces a non-top-level subtree with an empty query (Artur Zakirov)

  • Fix performance problems in ts_rewrite() (Tom Lane)

  • Fix ts_rewrite()'s handling of nested NOT operators (Tom Lane)

  • Improve speed of user-defined aggregates that use array_append() as transition function (Tom Lane)

  • Fix array_fill() to handle empty arrays properly (Tom Lane)

  • Fix possible crash in array_position() or array_positions() when processing arrays of records (Junseok Yang)

  • Fix one-byte buffer overrun in quote_literal_cstr() (Heikki Linnakangas)

    The overrun occurred only if the input consisted entirely of single quotes and/or backslashes.

  • Prevent multiple calls of pg_start_backup() and pg_stop_backup() from running concurrently (Michael Paquier)

    This avoids an assertion failure, and possibly worse things, if someone tries to run these functions in parallel.

  • Disable transform that attempted to remove no-op AT TIME ZONE conversions (Tom Lane)

    This resulted in wrong answers when the simplified expression was used in an index condition.

  • Avoid discarding interval-to-interval casts that aren't really no-ops (Tom Lane)

    In some cases, a cast that should result in zeroing out low-order interval fields was mistakenly deemed to be a no-op and discarded. An example is that casting from INTERVAL MONTH to INTERVAL YEAR failed to clear the months field.

  • Fix crash if the number of workers available to a parallel query decreases during a rescan (Andreas Seltenreich)

  • Fix bugs in transmitting GUC parameter values to parallel workers (Michael Paquier, Tom Lane)

  • Allow statements prepared with PREPARE to be given parallel plans (Amit Kapila, Tobias Bussmann)

  • Fix incorrect generation of parallel plans for semi-joins (Tom Lane)

  • Fix planner's cardinality estimates for parallel joins (Robert Haas)

    Ensure that these estimates reflect the number of rows predicted to be seen by each worker, rather than the total.

  • Fix planner to avoid trying to parallelize plan nodes containing initplans or subplans (Tom Lane, Amit Kapila)

  • Ensure that cached plans are invalidated by changes in foreign-table options (Amit Langote, Etsuro Fujita, Ashutosh Bapat)

  • Fix the plan generated for sorted partial aggregation with a constant GROUP BY clause (Tom Lane)

  • Fix "could not find plan for CTE" planner error when dealing with a UNION ALL containing CTE references (Tom Lane)

  • Fix mishandling of initplans when forcibly adding a Material node to a subplan (Tom Lane)

    The typical consequence of this mistake was a "plan should not reference subplan's variable" error.

  • Fix foreign-key-based join selectivity estimation for semi-joins and anti-joins, as well as inheritance cases (Tom Lane)

    The new code for taking the existence of a foreign key relationship into account did the wrong thing in these cases, making the estimates worse not better than the pre-9.6 code.

  • Fix pg_dump to emit the data of a sequence that is marked as an extension configuration table (Michael Paquier)

  • Fix mishandling of ALTER DEFAULT PRIVILEGES ... REVOKE in pg_dump (Stephen Frost)

    pg_dump missed issuing the required REVOKE commands in cases where ALTER DEFAULT PRIVILEGES had been used to reduce privileges to less than they would normally be.

  • Fix pg_dump to dump user-defined casts and transforms that use built-in functions (Stephen Frost)

  • Fix pg_restore with --create --if-exists to behave more sanely if an archive contains unrecognized DROP commands (Tom Lane)

    This doesn't fix any live bug, but it may improve the behavior in future if pg_restore is used with an archive generated by a later pg_dump version.

  • Fix pg_basebackup's rate limiting in the presence of slow I/O (Antonin Houska)

    If disk I/O was transiently much slower than the specified rate limit, the calculation overflowed, effectively disabling the rate limit for the rest of the run.

  • Fix pg_basebackup's handling of symlinked pg_stat_tmp and pg_replslot subdirectories (Magnus Hagander, Michael Paquier)

  • Fix possible pg_basebackup failure on standby server when including WAL files (Amit Kapila, Robert Haas)

  • Improve initdb to insert the correct platform-specific default values for the xxx_flush_after parameters into postgresql.conf (Fabien Coelho, Tom Lane)

    This is a cleaner way of documenting the default values than was used previously.

  • Fix possible mishandling of expanded arrays in domain check constraints and CASE execution (Tom Lane)

    It was possible for a PL/pgSQL function invoked in these contexts to modify or even delete an array value that needs to be preserved for additional operations.

  • Fix nested uses of PL/pgSQL functions in contexts such as domain check constraints evaluated during assignment to a PL/pgSQL variable (Tom Lane)

  • Ensure that the Python exception objects we create for PL/Python are properly reference-counted (Rafa de la Torre, Tom Lane)

    This avoids failures if the objects are used after a Python garbage collection cycle has occurred.

  • Fix PL/Tcl to support triggers on tables that have .tupno as a column name (Tom Lane)

    This matches the (previously undocumented) behavior of PL/Tcl's spi_exec and spi_execp commands, namely that a magic .tupno column is inserted only if there isn't a real column named that.

  • Allow DOS-style line endings in ~/.pgpass files, even on Unix (Vik Fearing)

    This change simplifies use of the same password file across Unix and Windows machines.

  • Fix one-byte buffer overrun if ecpg is given a file name that ends with a dot (Takayuki Tsunakawa)

  • Fix incorrect error reporting for duplicate data in psql's \crosstabview (Tom Lane)

    psql sometimes quoted the wrong row and/or column values when complaining about multiple entries for the same crosstab cell.

  • Fix psql's tab completion for ALTER DEFAULT PRIVILEGES (Gilles Darold, Stephen Frost)

  • Fix psql's tab completion for ALTER TABLE t ALTER c DROP ... (Kyotaro Horiguchi)

  • In psql, treat an empty or all-blank setting of the PAGER environment variable as meaning "no pager" (Tom Lane)

    Previously, such a setting caused output intended for the pager to vanish entirely.

  • Improve contrib/dblink's reporting of low-level libpq errors, such as out-of-memory (Joe Conway)

  • Teach contrib/dblink to ignore irrelevant server options when it uses a contrib/postgres_fdw foreign server as the source of connection options (Corey Huinker)

    Previously, if the foreign server object had options that were not also libpq connection options, an error occurred.

  • Fix portability problems in contrib/pageinspect's functions for GIN indexes (Peter Eisentraut, Tom Lane)

  • Fix possible miss of socket read events while waiting on Windows (Amit Kapila)

    This error was harmless for most uses, but it is known to cause hangs when trying to use the pldebugger extension.

  • On Windows, ensure that environment variable changes are propagated to DLLs built with debug options (Christian Ullrich)

  • Sync our copy of the timezone library with IANA release tzcode2016j (Tom Lane)

    This fixes various issues, most notably that timezone data installation failed if the target directory didn't support hard links.

  • Update time zone data files to tzdata release 2016j for DST law changes in northern Cyprus (adding a new zone Asia/Famagusta), Russia (adding a new zone Europe/Saratov), Tonga, and Antarctica/Casey. Historical corrections for Italy, Kazakhstan, Malta, and Palestine. Switch to preferring numeric zone abbreviations for Tonga.

• ⇑ Upgrade to 9.6.3 released on 2017-05-11 - docs

  • Restrict visibility of pg_user_mappings.umoptions, to protect passwords stored as user mapping options (Michael Paquier, Feike Steenbergen)

    The previous coding allowed the owner of a foreign server object, or anyone he has granted server USAGE permission to, to see the options for all user mappings associated with that server. This might well include passwords for other users. Adjust the view definition to match the behavior of information_schema.user_mapping_options, namely that these options are visible to the user being mapped, or if the mapping is for PUBLIC and the current user is the server owner, or if the current user is a superuser. (CVE-2017-7486)

    By itself, this patch will only fix the behavior in newly initdb'd databases. If you wish to apply this change in an existing database, follow the corrected procedure shown in the changelog entry for CVE-2017-7547, in Section E.13.

  • Prevent exposure of statistical information via leaky operators (Peter Eisentraut)

    Some selectivity estimation functions in the planner will apply user-defined operators to values obtained from pg_statistic, such as most common values and histogram entries. This occurs before table permissions are checked, so a nefarious user could exploit the behavior to obtain these values for table columns he does not have permission to read. To fix, fall back to a default estimate if the operator's implementation function is not certified leak-proof and the calling user does not have permission to read the table column whose statistics are needed. At least one of these criteria is satisfied in most cases in practice. (CVE-2017-7484)

  • Restore libpq's recognition of the PGREQUIRESSL environment variable (Daniel Gustafsson)

    Processing of this environment variable was unintentionally dropped in PostgreSQL 9.3, but its documentation remained. This creates a security hazard, since users might be relying on the environment variable to force SSL-encrypted connections, but that would no longer be guaranteed. Restore handling of the variable, but give it lower priority than PGSSLMODE, to avoid breaking configurations that work correctly with post-9.3 code. (CVE-2017-7485)

  • Fix possibly-invalid initial snapshot during logical decoding (Petr Jelinek, Andres Freund)

    The initial snapshot created for a logical decoding replication slot was potentially incorrect. This could cause third-party tools that use logical decoding to copy incomplete/inconsistent initial data. This was more likely to happen if the source server was busy at the time of slot creation, or if another logical slot already existed.

    If you are using a replication tool that depends on logical decoding, and it should have copied a nonempty data set at the start of replication, it is advisable to recreate the replica after installing this update, or to verify its contents against the source server.

  • Fix possible corruption of "init forks" of unlogged indexes (Robert Haas, Michael Paquier)

    This could result in an unlogged index being set to an invalid state after a crash and restart. Such a problem would persist until the index was dropped and rebuilt.

  • Fix incorrect reconstruction of pg_subtrans entries when a standby server replays a prepared but uncommitted two-phase transaction (Tom Lane)

    In most cases this turned out to have no visible ill effects, but in corner cases it could result in circular references in pg_subtrans, potentially causing infinite loops in queries that examine rows modified by the two-phase transaction.

  • Avoid possible crash in walsender due to failure to initialize a string buffer (Stas Kelvich, Fujii Masao)

  • Fix possible crash when rescanning a nearest-neighbor index-only scan on a GiST index (Tom Lane)

  • Prevent delays in postmaster's launching of multiple parallel worker processes (Tom Lane)

    There could be a significant delay (up to tens of seconds) before satisfying a query's request for more than one worker process, or when multiple queries requested workers simultaneously. On most platforms this required unlucky timing, but on some it was the typical case.

  • Fix postmaster's handling of fork() failure for a background worker process (Tom Lane)

    Previously, the postmaster updated portions of its state as though the process had been launched successfully, resulting in subsequent confusion.

  • Fix possible "no relation entry for relid 0" error when planning nested set operations (Tom Lane)

  • Fix assorted minor issues in planning of parallel queries (Robert Haas)

  • Avoid applying "physical targetlist" optimization to custom scans (Dmitry Ivanov, Tom Lane)

    This optimization supposed that retrieving all columns of a tuple is inexpensive, which is true for ordinary Postgres tuples; but it might not be the case for a custom scan provider.

  • Use the correct sub-expression when applying a FOR ALL row-level-security policy (Stephen Frost)

    In some cases the WITH CHECK restriction would be applied when the USING restriction is more appropriate.

  • Ensure parsing of queries in extension scripts sees the results of immediately-preceding DDL (Julien Rouhaud, Tom Lane)

    Due to lack of a cache flush step between commands in an extension script file, non-utility queries might not see the effects of an immediately preceding catalog change, such as ALTER TABLE ... RENAME.

  • Skip tablespace privilege checks when ALTER TABLE ... ALTER COLUMN TYPE rebuilds an existing index (Noah Misch)

    The command failed if the calling user did not currently have CREATE privilege for the tablespace containing the index. That behavior seems unhelpful, so skip the check, allowing the index to be rebuilt where it is.

  • Fix ALTER TABLE ... VALIDATE CONSTRAINT to not recurse to child tables when the constraint is marked NO INHERIT (Amit Langote)

    This fix prevents unwanted "constraint does not exist" failures when no matching constraint is present in the child tables.

  • Avoid dangling pointer in COPY ... TO when row-level security is active for the source table (Tom Lane)

    Usually this had no ill effects, but sometimes it would cause unexpected errors or crashes.

  • Avoid accessing an already-closed relcache entry in CLUSTER and VACUUM FULL (Tom Lane)

    With some bad luck, this could lead to indexes on the target relation getting rebuilt with the wrong persistence setting.

  • Fix VACUUM to account properly for pages that could not be scanned due to conflicting page pins (Andrew Gierth)

    This tended to lead to underestimation of the number of tuples in the table. In the worst case of a small heavily-contended table, VACUUM could incorrectly report that the table contained no tuples, leading to very bad planning choices.

  • Ensure that bulk-tuple-transfer loops within a hash join are interruptible by query cancel requests (Tom Lane, Thomas Munro)

  • Fix incorrect support for certain box operators in SP-GiST (Nikita Glukhov)

    SP-GiST index scans using the operators &< &> &<| and |&> would yield incorrect answers.

  • Fix integer-overflow problems in interval comparison (Kyotaro Horiguchi, Tom Lane)

    The comparison operators for type interval could yield wrong answers for intervals larger than about 296000 years. Indexes on columns containing such large values should be reindexed, since they may be corrupt.

  • Fix cursor_to_xml() to produce valid output with tableforest = false (Thomas Munro, Peter Eisentraut)

    Previously it failed to produce a wrapping <table> element.

  • Fix roundoff problems in float8_timestamptz() and make_interval() (Tom Lane)

    These functions truncated, rather than rounded, when converting a floating-point value to integer microseconds; that could cause unexpectedly off-by-one results.

  • Fix pg_get_object_address() to handle members of operator families correctly (Álvaro Herrera)

  • Fix cancelling of pg_stop_backup() when attempting to stop a non-exclusive backup (Michael Paquier, David Steele)

    If pg_stop_backup() was cancelled while waiting for a non-exclusive backup to end, related state was left inconsistent; a new exclusive backup could not be started, and there were other minor problems.

  • Improve performance of pg_timezone_names view (Tom Lane, David Rowley)

  • Reduce memory management overhead for contexts containing many large blocks (Tom Lane)

  • Fix sloppy handling of corner-case errors from lseek() and close() (Tom Lane)

    Neither of these system calls are likely to fail in typical situations, but if they did, fd.c could get quite confused.

  • Fix incorrect check for whether postmaster is running as a Windows service (Michael Paquier)

    This could result in attempting to write to the event log when that isn't accessible, so that no logging happens at all.

  • Fix ecpg to support COMMIT PREPARED and ROLLBACK PREPARED (Masahiko Sawada)

  • Fix a double-free error when processing dollar-quoted string literals in ecpg (Michael Meskes)

  • Fix pgbench to handle the combination of --connect and --rate options correctly (Fabien Coelho)

  • Fix pgbench to honor the long-form option spelling --builtin, as per its documentation (Tom Lane)

  • Fix pg_dump/pg_restore to correctly handle privileges for the public schema when using --clean option (Stephen Frost)

    Other schemas start out with no privileges granted, but public does not; this requires special-case treatment when it is dropped and restored due to the --clean option.

  • In pg_dump, fix incorrect schema and owner marking for comments and security labels of some types of database objects (Giuseppe Broccolo, Tom Lane)

    In simple cases this caused no ill effects; but for example, a schema-selective restore might omit comments it should include, because they were not marked as belonging to the schema of their associated object.

  • Fix typo in pg_dump's query for initial privileges of a procedural language (Peter Eisentraut)

    This resulted in pg_dump always believing that the language had no initial privileges. Since that's true for most procedural languages, ill effects from this bug are probably rare.

  • Avoid emitting an invalid list file in pg_restore -l when SQL object names contain newlines (Tom Lane)

    Replace newlines by spaces, which is sufficient to make the output valid for pg_restore -L's purposes.

  • Fix pg_upgrade to transfer comments and security labels attached to "large objects" (blobs) (Stephen Frost)

    Previously, blobs were correctly transferred to the new database, but any comments or security labels attached to them were lost.

  • Improve error handling in contrib/adminpack's pg_file_write() function (Noah Misch)

    Notably, it failed to detect errors reported by fclose().

  • In contrib/dblink, avoid leaking the previous unnamed connection when establishing a new unnamed connection (Joe Conway)

  • Fix contrib/pg_trgm's extraction of trigrams from regular expressions (Tom Lane)

    In some cases it would produce a broken data structure that could never match anything, leading to GIN or GiST indexscans that use a trigram index not finding any matches to the regular expression.

  • In contrib/postgres_fdw, allow join conditions that contain shippable extension-provided functions to be pushed to the remote server (David Rowley, Ashutosh Bapat)

  • Support Tcl 8.6 in MSVC builds (Álvaro Herrera)

  • Sync our copy of the timezone library with IANA release tzcode2017b (Tom Lane)

    This fixes a bug affecting some DST transitions in January 2038.

  • Update time zone data files to tzdata release 2017b for DST law changes in Chile, Haiti, and Mongolia, plus historical corrections for Ecuador, Kazakhstan, Liberia, and Spain. Switch to numeric abbreviations for numerous time zones in South America, the Pacific and Indian oceans, and some Asian and Middle Eastern countries.

    The IANA time zone database previously provided textual abbreviations for all time zones, sometimes making up abbreviations that have little or no currency among the local population. They are in process of reversing that policy in favor of using numeric UTC offsets in zones where there is no evidence of real-world use of an English abbreviation. At least for the time being, PostgreSQL will continue to accept such removed abbreviations for timestamp input. But they will not be shown in the pg_timezone_names view nor used for output.

  • Use correct daylight-savings rules for POSIX-style time zone names in MSVC builds (David Rowley)

    The Microsoft MSVC build scripts neglected to install the posixrules file in the timezone directory tree. This resulted in the timezone code falling back to its built-in rule about what DST behavior to assume for a POSIX-style time zone name. For historical reasons that still corresponds to the DST rules the USA was using before 2007 (i.e., change on first Sunday in April and last Sunday in October). With this fix, a POSIX-style zone name will use the current and historical DST transition dates of the US/Eastern zone. If you don't want that, remove the posixrules file, or replace it with a copy of some other zone file (see Section 8.5.3). Note that due to caching, you may need to restart the server to get such changes to take effect.

• ⇑ Upgrade to 9.6.4 released on 2017-08-10 - docs

  • Further restrict visibility of pg_user_mappings.umoptions, to protect passwords stored as user mapping options (Noah Misch)

    The fix for CVE-2017-7486 was incorrect: it allowed a user to see the options in her own user mapping, even if she did not have USAGE permission on the associated foreign server. Such options might include a password that had been provided by the server owner rather than the user herself. Since information_schema.user_mapping_options does not show the options in such cases, pg_user_mappings should not either. (CVE-2017-7547)

    By itself, this patch will only fix the behavior in newly initdb'd databases. If you wish to apply this change in an existing database, you will need to do the following:

    1. Restart the postmaster after adding allow_system_table_mods = true to postgresql.conf. (In versions supporting ALTER SYSTEM, you can use that to make the configuration change, but you'll still need a restart.)

    2. In each database of the cluster, run the following commands as superuser:

       SET search_path = pg_catalog;
       CREATE OR REPLACE VIEW pg_user_mappings AS
           SELECT
               U.oid       AS umid,
               S.oid       AS srvid,
               S.srvname   AS srvname,
               U.umuser    AS umuser,
               CASE WHEN U.umuser = 0 THEN
                   'public'
               ELSE
                   A.rolname
               END AS usename,
               CASE WHEN (U.umuser <> 0 AND A.rolname = current_user
                            AND (pg_has_role(S.srvowner, 'USAGE')
                                 OR has_server_privilege(S.oid, 'USAGE')))
                           OR (U.umuser = 0 AND pg_has_role(S.srvowner, 'USAGE'))
                           OR (SELECT rolsuper FROM pg_authid WHERE rolname = current_user)
                           THEN U.umoptions
                        ELSE NULL END AS umoptions
           FROM pg_user_mapping U
                LEFT JOIN pg_authid A ON (A.oid = U.umuser) JOIN
               pg_foreign_server S ON (U.umserver = S.oid);

    3. Do not forget to include the template0 and template1 databases, or the vulnerability will still exist in databases you create later. To fix template0, you'll need to temporarily make it accept connections. In PostgreSQL 9.5 and later, you can use

       ALTER DATABASE template0 WITH ALLOW_CONNECTIONS true;

       and then after fixing template0, undo that with

       ALTER DATABASE template0 WITH ALLOW_CONNECTIONS false;

       In prior versions, instead use

       UPDATE pg_database SET datallowconn = true WHERE datname = 'template0';
       UPDATE pg_database SET datallowconn = false WHERE datname = 'template0';

    4. Finally, remove the allow_system_table_mods configuration setting, and again restart the postmaster.

  • Disallow empty passwords in all password-based authentication methods (Heikki Linnakangas)

    libpq ignores empty password specifications, and does not transmit them to the server. So, if a user's password has been set to the empty string, it's impossible to log in with that password via psql or other libpq-based clients. An administrator might therefore believe that setting the password to empty is equivalent to disabling password login. However, with a modified or non-libpq-based client, logging in could be possible, depending on which authentication method is configured. In particular the most common method, md5, accepted empty passwords. Change the server to reject empty passwords in all cases. (CVE-2017-7546)

  • Make lo_put() check for UPDATE privilege on the target large object (Tom Lane, Michael Paquier)

    lo_put() should surely require the same permissions as lowrite(), but the check was missing, allowing any user to change the data in a large object. (CVE-2017-7548)

  • Correct the documentation about the process for upgrading standby servers with pg_upgrade (Bruce Momjian)

    The previous documentation instructed users to start/stop the primary server after running pg_upgrade but before syncing the standby servers. This sequence is unsafe.

  • Fix concurrent locking of tuple update chains (Álvaro Herrera)

    If several sessions concurrently lock a tuple update chain with nonconflicting lock modes using an old snapshot, and they all succeed, it was possible for some of them to nonetheless fail (and conclude there is no live tuple version) due to a race condition. This had consequences such as foreign-key checks failing to see a tuple that definitely exists but is being updated concurrently.

  • Fix potential data corruption when freezing a tuple whose XMAX is a multixact with exactly one still-interesting member (Teodor Sigaev)

  • Avoid integer overflow and ensuing crash when sorting more than one billion tuples in-memory (Sergey Koposov)

  • On Windows, retry process creation if we fail to reserve the address range for our shared memory in the new process (Tom Lane, Amit Kapila)

    This is expected to fix infrequent child-process-launch failures that are probably due to interference from antivirus products.

  • Fix low-probability corruption of shared predicate-lock hash table in Windows builds (Thomas Munro, Tom Lane)

  • Avoid logging clean closure of an SSL connection as though it were a connection reset (Michael Paquier)

  • Prevent sending SSL session tickets to clients (Tom Lane)

    This fix prevents reconnection failures with ticket-aware client-side SSL code.

  • Fix code for setting tcp_keepalives_idle on Solaris (Tom Lane)

  • Fix statistics collector to honor inquiry messages issued just after a postmaster shutdown and immediate restart (Tom Lane)

    Statistics inquiries issued within half a second of the previous postmaster shutdown were effectively ignored.

  • Ensure that the statistics collector's receive buffer size is at least 100KB (Tom Lane)

    This reduces the risk of dropped statistics data on older platforms whose default receive buffer size is less than that.

  • Fix possible creation of an invalid WAL segment when a standby is promoted just after it processes an XLOG_SWITCH WAL record (Andres Freund)

  • Fix walsender to exit promptly when client requests shutdown (Tom Lane)

  • Fix SIGHUP and SIGUSR1 handling in walsender processes (Petr Jelinek, Andres Freund)

  • Prevent walsender-triggered panics during shutdown checkpoints (Andres Freund, Michael Paquier)

  • Fix unnecessarily slow restarts of walreceiver processes due to race condition in postmaster (Tom Lane)

  • Fix leakage of small subtransactions spilled to disk during logical decoding (Andres Freund)

    This resulted in temporary files consuming excessive disk space.

  • Reduce the work needed to build snapshots during creation of logical-decoding slots (Andres Freund, Petr Jelinek)

    The previous algorithm was infeasibly expensive on a server with a lot of open transactions.

  • Fix race condition that could indefinitely delay creation of logical-decoding slots (Andres Freund, Petr Jelinek)

  • Reduce overhead in processing syscache invalidation events (Tom Lane)

    This is particularly helpful for logical decoding, which triggers frequent cache invalidation.

  • Remove incorrect heuristic used in some cases to estimate join selectivity based on the presence of foreign-key constraints (David Rowley)

    In some cases where a multi-column foreign key constraint existed but did not exactly match a query's join structure, the planner used an estimation heuristic that turns out not to work well at all. Revert such cases to the way they were estimated before 9.6.

  • Fix cases where an INSERT or UPDATE assigns to more than one element of a column that is of domain-over-array type (Tom Lane)

  • Allow window functions to be used in sub-SELECTs that are within the arguments of an aggregate function (Tom Lane)

  • Ensure that a view's CHECK OPTIONS clause is enforced properly when the underlying table is a foreign table (Etsuro Fujita)

    Previously, the update might get pushed entirely to the foreign server, but the need to verify the view conditions was missed if so.

  • Move autogenerated array types out of the way during ALTER ... RENAME (Vik Fearing)

    Previously, we would rename a conflicting autogenerated array type out of the way during CREATE; this fix extends that behavior to renaming operations.

  • Fix dangling pointer in ALTER TABLE when there is a comment on a constraint belonging to the table (David Rowley)

    Re-applying the comment to the reconstructed constraint could fail with a weird error message, or even crash.

  • Ensure that ALTER USER ... SET accepts all the syntax variants that ALTER ROLE ... SET does (Peter Eisentraut)

  • Allow a foreign table's CHECK constraints to be initially NOT VALID (Amit Langote)

    CREATE TABLE silently drops NOT VALID specifiers for CHECK constraints, reasoning that the table must be empty so the constraint can be validated immediately. But this is wrong for CREATE FOREIGN TABLE, where there's no reason to suppose that the underlying table is empty, and even if it is it's no business of ours to decide that the constraint can be treated as valid going forward. Skip this "optimization" for foreign tables.

  • Properly update dependency info when changing a datatype I/O function's argument or return type from opaque to the correct type (Heikki Linnakangas)

    CREATE TYPE updates I/O functions declared in this long-obsolete style, but it forgot to record a dependency on the type, allowing a subsequent DROP TYPE to leave broken function definitions behind.

  • Allow parallelism in the query plan when COPY copies from a query's result (Andres Freund)

  • Reduce memory usage when ANALYZE processes a tsvector column (Heikki Linnakangas)

  • Fix unnecessary precision loss and sloppy rounding when multiplying or dividing money values by integers or floats (Tom Lane)

  • Tighten checks for whitespace in functions that parse identifiers, such as regprocedurein() (Tom Lane)

    Depending on the prevailing locale, these functions could misinterpret fragments of multibyte characters as whitespace.

  • Use relevant #define symbols from Perl while compiling PL/Perl (Ashutosh Sharma, Tom Lane)

    This avoids portability problems, typically manifesting as a "handshake" mismatch during library load, when working with recent Perl versions.

  • In libpq, reset GSS/SASL and SSPI authentication state properly after a failed connection attempt (Michael Paquier)

    Failure to do this meant that when falling back from SSL to non-SSL connections, a GSS/SASL failure in the SSL attempt would always cause the non-SSL attempt to fail. SSPI did not fail, but it leaked memory.

  • In psql, fix failure when COPY FROM STDIN is ended with a keyboard EOF signal and then another COPY FROM STDIN is attempted (Thomas Munro)

    This misbehavior was observed on BSD-derived platforms (including macOS), but not on most others.

  • Fix pg_dump and pg_restore to emit REFRESH MATERIALIZED VIEW commands last (Tom Lane)

    This prevents errors during dump/restore when a materialized view refers to tables owned by a different user.

  • Improve pg_dump/pg_restore's reporting of error conditions originating in zlib (Vladimir Kunschikov, Álvaro Herrera)

  • Fix pg_dump with the --clean option to drop event triggers as expected (Tom Lane)

    It also now correctly assigns ownership of event triggers; before, they were restored as being owned by the superuser running the restore script.

  • Fix pg_dump with the --clean option to not fail when the public schema doesn't exist (Stephen Frost)

  • Fix pg_dump to not emit invalid SQL for an empty operator class (Daniel Gustafsson)

  • Fix pg_dump output to stdout on Windows (Kuntal Ghosh)

    A compressed plain-text dump written to stdout would contain corrupt data due to failure to put the file descriptor into binary mode.

  • Fix pg_get_ruledef() to print correct output for the ON SELECT rule of a view whose columns have been renamed (Tom Lane)

    In some corner cases, pg_dump relies on pg_get_ruledef() to dump views, so that this error could result in dump/reload failures.

  • Fix dumping of outer joins with empty constraints, such as the result of a NATURAL LEFT JOIN with no common columns (Tom Lane)

  • Fix dumping of function expressions in the FROM clause in cases where the expression does not deparse into something that looks like a function call (Tom Lane)

  • Fix pg_basebackup output to stdout on Windows (Haribabu Kommi)

    A backup written to stdout would contain corrupt data due to failure to put the file descriptor into binary mode.

  • Fix pg_rewind to correctly handle files exceeding 2GB (Kuntal Ghosh, Michael Paquier)

    Ordinarily such files won't appear in PostgreSQL data directories, but they could be present in some cases.

  • Fix pg_upgrade to ensure that the ending WAL record does not have wal_level = minimum (Bruce Momjian)

    This condition could prevent upgraded standby servers from reconnecting.

  • Fix pg_xlogdump's computation of WAL record length (Andres Freund)

  • In postgres_fdw, re-establish connections to remote servers after ALTER SERVER or ALTER USER MAPPING commands (Kyotaro Horiguchi)

    This ensures that option changes affecting connection parameters will be applied promptly.

  • In postgres_fdw, allow cancellation of remote transaction control commands (Robert Haas, Rafia Sabih)

    This change allows us to quickly escape a wait for an unresponsive remote server in many more cases than previously.

  • Increase MAX_SYSCACHE_CALLBACKS to provide more room for extensions (Tom Lane)

  • Always use -fPIC, not -fpic, when building shared libraries with gcc (Tom Lane)

    This supports larger extension libraries on platforms where it makes a difference.

  • In MSVC builds, handle the case where the openssl library is not within a VC subdirectory (Andrew Dunstan)

  • In MSVC builds, add proper include path for libxml2 header files (Andrew Dunstan)

    This fixes a former need to move things around in standard Windows installations of libxml2.

  • In MSVC builds, recognize a Tcl library that is named tcl86.lib (Noah Misch)

  • In MSVC builds, honor PROVE_FLAGS settings on vcregress.pl's command line (Andrew Dunstan)

• ⇑ Upgrade to 9.6.5 released on 2017-08-31 - docs

  • Show foreign tables in information_schema.table_privileges view (Peter Eisentraut)

    All other relevant information_schema views include foreign tables, but this one ignored them.

    Since this view definition is installed by initdb, merely upgrading will not fix the problem. If you need to fix this in an existing installation, you can, as a superuser, do this in psql:

    SET search_path TO information_schema;
    CREATE OR REPLACE VIEW table_privileges AS
        SELECT CAST(u_grantor.rolname AS sql_identifier) AS grantor,
               CAST(grantee.rolname AS sql_identifier) AS grantee,
               CAST(current_database() AS sql_identifier) AS table_catalog,
               CAST(nc.nspname AS sql_identifier) AS table_schema,
               CAST(c.relname AS sql_identifier) AS table_name,
               CAST(c.prtype AS character_data) AS privilege_type,
               CAST(
                 CASE WHEN
                      -- object owner always has grant options
                      pg_has_role(grantee.oid, c.relowner, 'USAGE')
                      OR c.grantable
                      THEN 'YES' ELSE 'NO' END AS yes_or_no) AS is_grantable,
               CAST(CASE WHEN c.prtype = 'SELECT' THEN 'YES' ELSE 'NO' END AS yes_or_no) AS with_hierarchy
    
        FROM (
                SELECT oid, relname, relnamespace, relkind, relowner, (aclexplode(coalesce(relacl, acldefault('r', relowner)))).* FROM pg_class
             ) AS c (oid, relname, relnamespace, relkind, relowner, grantor, grantee, prtype, grantable),
             pg_namespace nc,
             pg_authid u_grantor,
             (
               SELECT oid, rolname FROM pg_authid
               UNION ALL
               SELECT 0::oid, 'PUBLIC'
             ) AS grantee (oid, rolname)
    
        WHERE c.relnamespace = nc.oid
              AND c.relkind IN ('r', 'v', 'f')
              AND c.grantee = grantee.oid
              AND c.grantor = u_grantor.oid
              AND c.prtype IN ('INSERT', 'SELECT', 'UPDATE', 'DELETE', 'TRUNCATE', 'REFERENCES', 'TRIGGER')
              AND (pg_has_role(u_grantor.oid, 'USAGE')
                   OR pg_has_role(grantee.oid, 'USAGE')
                   OR grantee.rolname = 'PUBLIC');

    This must be repeated in each database to be fixed, including template0.

  • Clean up handling of a fatal exit (e.g., due to receipt of SIGTERM) that occurs while trying to execute a ROLLBACK of a failed transaction (Tom Lane)

    This situation could result in an assertion failure. In production builds, the exit would still occur, but it would log an unexpected message about "cannot drop active portal".

  • Remove assertion that could trigger during a fatal exit (Tom Lane)

  • Correctly identify columns that are of a range type or domain type over a composite type or domain type being searched for (Tom Lane)

    Certain ALTER commands that change the definition of a composite type or domain type are supposed to fail if there are any stored values of that type in the database, because they lack the infrastructure needed to update or check such values. Previously, these checks could miss relevant values that are wrapped inside range types or sub-domains, possibly allowing the database to become inconsistent.

  • Prevent crash when passing fixed-length pass-by-reference data types to parallel worker processes (Tom Lane)

  • Fix crash in pg_restore when using parallel mode and using a list file to select a subset of items to restore (Fabrízio de Royes Mello)

  • Change ecpg's parser to allow RETURNING clauses without attached C variables (Michael Meskes)

    This allows ecpg programs to contain SQL constructs that use RETURNING internally (for example, inside a CTE) rather than using it to define values to be returned to the client.

  • Change ecpg's parser to recognize backslash continuation of C preprocessor command lines (Michael Meskes)

  • Improve selection of compiler flags for PL/Perl on Windows (Tom Lane)

    This fix avoids possible crashes of PL/Perl due to inconsistent assumptions about the width of time_t values. A side-effect that may be visible to extension developers is that _USE_32BIT_TIME_T is no longer defined globally in PostgreSQL Windows builds. This is not expected to cause problems, because type time_t is not used in any PostgreSQL API definitions.

  • Fix make check to behave correctly when invoked via a non-GNU make program (Thomas Munro)

• ⇑ Upgrade to 9.6.6 released on 2017-11-09 - docs

  • Ensure that INSERT ... ON CONFLICT DO UPDATE checks table permissions and RLS policies in all cases (Dean Rasheed)

    The update path of INSERT ... ON CONFLICT DO UPDATE requires SELECT permission on the columns of the arbiter index, but it failed to check for that in the case of an arbiter specified by constraint name. In addition, for a table with row level security enabled, it failed to check updated rows against the table's SELECT policies (regardless of how the arbiter index was specified). (CVE-2017-15099)

  • Fix crash due to rowtype mismatch in json{b}_populate_recordset() (Michael Paquier, Tom Lane)

    These functions used the result rowtype specified in the FROM ... AS clause without checking that it matched the actual rowtype of the supplied tuple value. If it didn't, that would usually result in a crash, though disclosure of server memory contents seems possible as well. (CVE-2017-15098)

  • Fix sample server-start scripts to become $PGUSER before opening $PGLOG (Noah Misch)

    Previously, the postmaster log file was opened while still running as root. The database owner could therefore mount an attack against another system user by making $PGLOG be a symbolic link to some other file, which would then become corrupted by appending log messages.

    By default, these scripts are not installed anywhere. Users who have made use of them will need to manually recopy them, or apply the same changes to their modified versions. If the existing $PGLOG file is root-owned, it will need to be removed or renamed out of the way before restarting the server with the corrected script. (CVE-2017-12172)

  • Fix BRIN index summarization to handle concurrent table extension correctly (Álvaro Herrera)

    Previously, a race condition allowed some table rows to be omitted from the index. It may be necessary to reindex existing BRIN indexes to recover from past occurrences of this problem.

  • Fix possible failures during concurrent updates of a BRIN index (Tom Lane)

    These race conditions could result in errors like "invalid index offnum" or "inconsistent range map".

  • Fix crash when logical decoding is invoked from a SPI-using function, in particular any function written in a PL language (Tom Lane)

  • Fix incorrect query results when multiple GROUPING SETS columns contain the same simple variable (Tom Lane)

  • Fix incorrect parallelization decisions for nested queries (Amit Kapila, Kuntal Ghosh)

  • Fix parallel query handling to not fail when a recently-used role is dropped (Amit Kapila)

  • Fix json_build_array(), json_build_object(), and their jsonb equivalents to handle explicit VARIADIC arguments correctly (Michael Paquier)

  • Properly reject attempts to convert infinite float values to type numeric (Tom Lane, KaiGai Kohei)

    Previously the behavior was platform-dependent.

  • Fix corner-case crashes when columns have been added to the end of a view (Tom Lane)

  • Record proper dependencies when a view or rule contains FieldSelect or FieldStore expression nodes (Tom Lane)

    Lack of these dependencies could allow a column or data type DROP to go through when it ought to fail, thereby causing later uses of the view or rule to get errors. This patch does not do anything to protect existing views/rules, only ones created in the future.

  • Correctly detect hashability of range data types (Tom Lane)

    The planner mistakenly assumed that any range type could be hashed for use in hash joins or hash aggregation, but actually it must check whether the range's subtype has hash support. This does not affect any of the built-in range types, since they're all hashable anyway.

  • Correctly ignore RelabelType expression nodes when determining relation distinctness (David Rowley)

    This allows the intended optimization to occur when a subquery has a result column of type varchar.

  • Prevent sharing transition states between ordered-set aggregates (David Rowley)

    This causes a crash with the built-in ordered-set aggregates, and probably with user-written ones as well. v11 and later will include provisions for dealing with such cases safely, but in released branches, just disable the optimization.

  • Prevent idle_in_transaction_session_timeout from being ignored when a statement_timeout occurred earlier (Lukas Fittl)

  • Fix low-probability loss of NOTIFY messages due to XID wraparound (Marko Tiikkaja, Tom Lane)

    If a session executed no queries, but merely listened for notifications, for more than 2 billion transactions, it started to miss some notifications from concurrently-committing transactions.

  • Avoid SIGBUS crash on Linux when a DSM memory request exceeds the space available in tmpfs (Thomas Munro)

  • Reduce the frequency of data flush requests during bulk file copies to avoid performance problems on macOS, particularly with its new APFS file system (Tom Lane)

  • Prevent low-probability crash in processing of nested trigger firings (Tom Lane)

  • Allow COPY's FREEZE option to work when the transaction isolation level is REPEATABLE READ or higher (Noah Misch)

    This case was unintentionally broken by a previous bug fix.

  • Correctly restore the umask setting when file creation fails in COPY or lo_export() (Peter Eisentraut)

  • Give a better error message for duplicate column names in ANALYZE (Nathan Bossart)

  • Add missing cases in GetCommandLogLevel(), preventing errors when certain SQL commands are used while log_statement is set to ddl (Michael Paquier)

  • Fix mis-parsing of the last line in a non-newline-terminated pg_hba.conf file (Tom Lane)

  • Fix AggGetAggref() to return the correct Aggref nodes to aggregate final functions whose transition calculations have been merged (Tom Lane)

  • Fix pg_dump to ensure that it emits GRANT commands in a valid order (Stephen Frost)

  • Fix pg_basebackup's matching of tablespace paths to canonicalize both paths before comparing (Michael Paquier)

    This is particularly helpful on Windows.

  • Fix libpq to not require user's home directory to exist (Tom Lane)

    In v10, failure to find the home directory while trying to read ~/.pgpass was treated as a hard error, but it should just cause that file to not be found. Both v10 and previous release branches made the same mistake when reading ~/.pg_service.conf, though this was less obvious since that file is not sought unless a service name is specified.

  • Fix libpq to guard against integer overflow in the row count of a PGresult (Michael Paquier)

  • Fix ecpg's handling of out-of-scope cursor declarations with pointer or array variables (Michael Meskes)

  • In ecpglib, correctly handle backslashes in string literals depending on whether standard_conforming_strings is set (Tsunakawa Takayuki)

  • Make ecpglib's Informix-compatibility mode ignore fractional digits in integer input strings, as expected (Gao Zengqi, Michael Meskes)

  • Fix ecpg's regression tests to work reliably on Windows (Christian Ullrich, Michael Meskes)

  • Fix missing temp-install prerequisites for check-like Make targets (Noah Misch)

    Some non-default test procedures that are meant to work like make check failed to ensure that the temporary installation was up to date.

  • Sync our copy of the timezone library with IANA release tzcode2017c (Tom Lane)

    This fixes various issues; the only one likely to be user-visible is that the default DST rules for a POSIX-style zone name, if no posixrules file exists in the timezone data directory, now match current US law rather than what it was a dozen years ago.

  • Update time zone data files to tzdata release 2017c for DST law changes in Fiji, Namibia, Northern Cyprus, Sudan, Tonga, and Turks & Caicos Islands, plus historical corrections for Alaska, Apia, Burma, Calcutta, Detroit, Ireland, Namibia, and Pago Pago.

• ⇑ Upgrade to 9.6.7 released on 2018-02-08 - docs

  • Ensure that all temporary files made by pg_upgrade are non-world-readable (Tom Lane, Noah Misch)

    pg_upgrade normally restricts its temporary files to be readable and writable only by the calling user. But the temporary file containing pg_dumpall -g output would be group- or world-readable, or even writable, if the user's umask setting allows. In typical usage on multi-user machines, the umask and/or the working directory's permissions would be tight enough to prevent problems; but there may be people using pg_upgrade in scenarios where this oversight would permit disclosure of database passwords to unfriendly eyes. (CVE-2018-1053)

  • Fix vacuuming of tuples that were updated while key-share locked (Andres Freund, Álvaro Herrera)

    In some cases VACUUM would fail to remove such tuples even though they are now dead, leading to assorted data corruption scenarios.

  • Ensure that vacuum will always clean up the pending-insertions list of a GIN index (Masahiko Sawada)

    This is necessary to ensure that dead index entries get removed. The old code got it backwards, allowing vacuum to skip the cleanup if some other process were running cleanup concurrently, thus risking invalid entries being left behind in the index.

  • Fix inadequate buffer locking in some LSN fetches (Jacob Champion, Asim Praveen, Ashwin Agrawal)

    These errors could result in misbehavior under concurrent load. The potential consequences have not been characterized fully.

  • Fix incorrect query results from cases involving flattening of subqueries whose outputs are used in GROUPING SETS (Heikki Linnakangas)

  • Avoid unnecessary failure in a query on an inheritance tree that occurs concurrently with some child table being removed from the tree by ALTER TABLE NO INHERIT (Tom Lane)

  • Fix spurious deadlock failures when multiple sessions are running CREATE INDEX CONCURRENTLY (Jeff Janes)

  • Fix failures when an inheritance tree contains foreign child tables (Etsuro Fujita)

    A mix of regular and foreign tables in an inheritance tree resulted in creation of incorrect plans for UPDATE and DELETE queries. This led to visible failures in some cases, notably when there are row-level triggers on a foreign child table.

  • Repair failure with correlated sub-SELECT inside VALUES inside a LATERAL subquery (Tom Lane)

  • Fix "could not devise a query plan for the given query" planner failure for some cases involving nested UNION ALL inside a lateral subquery (Tom Lane)

  • Fix logical decoding to correctly clean up disk files for crashed transactions (Atsushi Torikoshi)

    Logical decoding may spill WAL records to disk for transactions generating many WAL records. Normally these files are cleaned up after the transaction's commit or abort record arrives; but if no such record is ever seen, the removal code misbehaved.

  • Fix walsender timeout failure and failure to respond to interrupts when processing a large transaction (Petr Jelinek)

  • Fix has_sequence_privilege() to support WITH GRANT OPTION tests, as other privilege-testing functions do (Joe Conway)

  • In databases using UTF8 encoding, ignore any XML declaration that asserts a different encoding (Pavel Stehule, Noah Misch)

    We always store XML strings in the database encoding, so allowing libxml to act on a declaration of another encoding gave wrong results. In encodings other than UTF8, we don't promise to support non-ASCII XML data anyway, so retain the previous behavior for bug compatibility. This change affects only xpath() and related functions; other XML code paths already acted this way.

  • Provide for forward compatibility with future minor protocol versions (Robert Haas, Badrul Chowdhury)

    Up to now, PostgreSQL servers simply rejected requests to use protocol versions newer than 3.0, so that there was no functional difference between the major and minor parts of the protocol version number. Allow clients to request versions 3.x without failing, sending back a message showing that the server only understands 3.0. This makes no difference at the moment, but back-patching this change should allow speedier introduction of future minor protocol upgrades.

  • Cope with failure to start a parallel worker process (Amit Kapila, Robert Haas)

    Parallel query previously tended to hang indefinitely if a worker could not be started, as the result of fork() failure or other low-probability problems.

  • Fix collection of EXPLAIN statistics from parallel workers (Amit Kapila, Thomas Munro)

  • Avoid unsafe alignment assumptions when working with __int128 (Tom Lane)

    Typically, compilers assume that __int128 variables are aligned on 16-byte boundaries, but our memory allocation infrastructure isn't prepared to guarantee that, and increasing the setting of MAXALIGN seems infeasible for multiple reasons. Adjust the code to allow use of __int128 only when we can tell the compiler to assume lesser alignment. The only known symptom of this problem so far is crashes in some parallel aggregation queries.

  • Prevent stack-overflow crashes when planning extremely deeply nested set operations (UNION/INTERSECT/EXCEPT) (Tom Lane)

  • Fix null-pointer crashes for some types of LDAP URLs appearing in pg_hba.conf (Thomas Munro)

  • Fix sample INSTR() functions in the PL/pgSQL documentation (Yugo Nagata, Tom Lane)

    These functions are stated to be Oracle® compatible, but they weren't exactly. In particular, there was a discrepancy in the interpretation of a negative third parameter: Oracle thinks that a negative value indicates the last place where the target substring can begin, whereas our functions took it as the last place where the target can end. Also, Oracle throws an error for a zero or negative fourth parameter, whereas our functions returned zero.

    The sample code has been adjusted to match Oracle's behavior more precisely. Users who have copied this code into their applications may wish to update their copies.

  • Fix pg_dump to make ACL (permissions), comment, and security label entries reliably identifiable in archive output formats (Tom Lane)

    The "tag" portion of an ACL archive entry was usually just the name of the associated object. Make it start with the object type instead, bringing ACLs into line with the convention already used for comment and security label archive entries. Also, fix the comment and security label entries for the whole database, if present, to make their tags start with DATABASE so that they also follow this convention. This prevents false matches in code that tries to identify large-object-related entries by seeing if the tag starts with LARGE OBJECT. That could have resulted in misclassifying entries as data rather than schema, with undesirable results in a schema-only or data-only dump.

    Note that this change has user-visible results in the output of pg_restore --list.

  • Rename pg_rewind's copy_file_range function to avoid conflict with new Linux system call of that name (Andres Freund)

    This change prevents build failures with newer glibc versions.

  • In ecpg, detect indicator arrays that do not have the correct length and report an error (David Rader)

  • Change the behavior of contrib/cube's cube ~> int operator to make it compatible with KNN search (Alexander Korotkov)

    The meaning of the second argument (the dimension selector) has been changed to make it predictable which value is selected even when dealing with cubes of varying dimensionalities.

    This is an incompatible change, but since the point of the operator was to be used in KNN searches, it seems rather useless as-is. After installing this update, any expression indexes or materialized views using this operator will need to be reindexed/refreshed.

  • Avoid triggering a libc assertion in contrib/hstore, due to use of memcpy() with equal source and destination pointers (Tomas Vondra)

  • Fix incorrect display of tuples' null bitmaps in contrib/pageinspect (Maksim Milyutin)

  • In contrib/postgres_fdw, avoid "outer pathkeys do not match mergeclauses" planner error when constructing a plan involving a remote join (Robert Haas)

  • Provide modern examples of how to auto-start Postgres on macOS (Tom Lane)

    The scripts in contrib/start-scripts/osx use infrastructure that's been deprecated for over a decade, and which no longer works at all in macOS releases of the last couple of years. Add a new subdirectory contrib/start-scripts/macos containing scripts that use the newer launchd infrastructure.

  • Fix incorrect selection of configuration-specific libraries for OpenSSL on Windows (Andrew Dunstan)

  • Support linking to MinGW-built versions of libperl (Noah Misch)

    This allows building PL/Perl with some common Perl distributions for Windows.

  • Fix MSVC build to test whether 32-bit libperl needs -D_USE_32BIT_TIME_T (Noah Misch)

    Available Perl distributions are inconsistent about what they expect, and lack any reliable means of reporting it, so resort to a build-time test on what the library being used actually does.

  • On Windows, install the crash dump handler earlier in postmaster startup (Takayuki Tsunakawa)

    This may allow collection of a core dump for some early-startup failures that did not produce a dump before.

  • On Windows, avoid encoding-conversion-related crashes when emitting messages very early in postmaster startup (Takayuki Tsunakawa)

  • Use our existing Motorola 68K spinlock code on OpenBSD as well as NetBSD (David Carlier)

  • Add support for spinlocks on Motorola 88K (David Carlier)

  • Update time zone data files to tzdata release 2018c for DST law changes in Brazil, Sao Tome and Principe, plus historical corrections for Bolivia, Japan, and South Sudan. The US/Pacific-New zone has been removed (it was only an alias for America/Los_Angeles anyway).

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