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POSTGRESQL · VERSION COMPARE

PostgreSQL 9.5.21 release changes

All features, fixes, and compatibility notes in this release, with related records from other versions.

All changes in this release
All changes in this release

Includes changes after the source version through the target. A major version name means its initial release.

From PostgreSQL 9.0 onward: 17 major branches and 352 release notes. Updated 2026-09-26.

Complete release changes

9.5.21

2020-02-13

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29changesFeatures, fixes, improvements
1releaseGrouped by release
0CVEsVulnerability IDs mentioned in these notes

9.5.21 HistoricalSupport ends 2021-02-11

PostgreSQL 9.5.21

Migration and compatibility

A dump/restore is not required for those running 9.5.X.

However, if you are upgrading from a version earlier than 9.5.20, see Section E.6.

ImprovementsAvoid failure in logical decoding when a large transaction must be spilled into many separate temporary files

Changes

Avoid failure in logical decoding when a large transaction must be spilled into many separate temporary files (Amit Khandekar)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix failure in logical replication publisher after a database crash and restart

Changes

Fix failure in logical replication publisher after a database crash and restart (Vignesh C)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesAvoid memory leak when there are no free dynamic shared memory slots

Changes

Avoid memory leak when there are no free dynamic shared memory slots (Thomas Munro)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsIgnore the CONCURRENTLY option when performing an index creation, drop, or rebuild on a temporary table

Changes

Ignore the CONCURRENTLY option when performing an index creation, drop, or rebuild on a temporary table (Michael Paquier, Heikki Linnakangas, Andres Freund)

This avoids strange failures if the temporary table has an ON COMMIT action. There is no benefit in using CONCURRENTLY for a temporary table anyway, since other sessions cannot access the table, making the extra processing pointless.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix possible failure when resetting expression indexes on temporary tables that are marked ON COMMIT DELETE ROWS

Changes

Fix possible failure when resetting expression indexes on temporary tables that are marked ON COMMIT DELETE ROWS (Tom Lane)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix possible crash in BRIN index operations with box, range and inet data types

Changes

Fix possible crash in BRIN index operations with box, range and inet data types (Heikki Linnakangas)

Related records (4)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix handling of deleted pages in GIN indexes

Changes

Fix handling of deleted pages in GIN indexes (Alexander Korotkov)

Avoid possible deadlocks, incorrect updates of a deleted page's state, and failure to traverse through a recently-deleted page.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix possible crash with a SubPlan (sub-SELECT) within a multi-row VALUES list

Changes

Fix possible crash with a SubPlan (sub-SELECT) within a multi-row VALUES list (Tom Lane)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix unlikely crash with pass-by-reference aggregate transition states

Changes

Fix unlikely crash with pass-by-reference aggregate transition states (Andres Freund, Teodor Sigaev)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsImprove error reporting in to_date() and to_timestamp()

Changes

Improve error reporting in to_date() and to_timestamp() (Tom Lane, Álvaro Herrera)

Reports about incorrect month or day names in input strings could truncate the input in the middle of a multi-byte character, leading to an improperly encoded error message that could cause follow-on failures. Truncate at the next whitespace instead.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix off-by-one result for EXTRACT(ISOYEAR FROM timestamp) for BC dates

Changes

Fix off-by-one result for EXTRACT(ISOYEAR FROM timestamp) for BC dates (Tom Lane)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesAvoid stack overflow in information_schema views when a self-referential view exists in the system catalogs

Changes

Avoid stack overflow in information_schema views when a self-referential view exists in the system catalogs (Tom Lane)

A self-referential view can't work; it will always result in infinite recursion. We handled that situation correctly when trying to execute the view, but not when inquiring whether it is automatically updatable.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

PerformanceImprove performance of hash joins with very large inner relations

Changes

Improve performance of hash joins with very large inner relations (Thomas Munro)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix edge-case crashes and misestimations in selectivity calculations for the <@ and @> range operators

Changes

Fix edge-case crashes and misestimations in selectivity calculations for the <@ and @> range operators (Michael Paquier, Andrey Borodin, Tom Lane)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsImprove error reporting for attempts to use automatic updating of views with conditional INSTEAD rules

Changes

Improve error reporting for attempts to use automatic updating of views with conditional INSTEAD rules (Dean Rasheed)

This has never been supported, but previously the error was thrown only at execution time, so that it could be masked by planner errors.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsPrevent a composite type from being included in itself indirectly via a range type

Changes

Prevent a composite type from being included in itself indirectly via a range type (Tom Lane, Julien Rouhaud)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix error reporting for index expressions of prohibited types

Changes

Fix error reporting for index expressions of prohibited types (Amit Langote)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix dumping of views that contain only a VALUES list to handle cases where a view output column has been renamed

Changes

Fix dumping of views that contain only a VALUES list to handle cases where a view output column has been renamed (Tom Lane)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsAllow libpq to parse all GSS-related connection parameters even when the GSSAPI code hasn't been compiled in

Changes

Allow libpq to parse all GSS-related connection parameters even when the GSSAPI code hasn't been compiled in (Tom Lane)

This makes the behavior similar to our SSL support, where it was long ago deemed to be a good idea to always accept all the related parameters, even if some are ignored or restricted due to lack of the feature in a particular build.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix incorrect handling of %b and %B format codes in ecpg's PGTYPEStimestamp_fmt_asc() function

Changes

Fix incorrect handling of %b and %B format codes in ecpg's PGTYPEStimestamp_fmt_asc() function (Tomas Vondra)

Due to an off-by-one error, these codes would print the wrong month name, or possibly crash.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix parallel pg_dump/pg_restore to more gracefully handle failure to create worker processes

Changes

Fix parallel pg_dump/pg_restore to more gracefully handle failure to create worker processes (Tom Lane)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesPrevent possible crash or lockup when attempting to terminate a parallel pg_dump/pg_restore run via a signal

Changes

Prevent possible crash or lockup when attempting to terminate a parallel pg_dump/pg_restore run via a signal (Tom Lane)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsIn pg_upgrade, look inside arrays and ranges while searching for non-upgradable data types in tables

Changes

In pg_upgrade, look inside arrays and ranges while searching for non-upgradable data types in tables (Tom Lane)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsApply more thorough syntax checking to createuser's --connection-limit option

Changes

Apply more thorough syntax checking to createuser's --connection-limit option (Álvaro Herrera)

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsIn contrib/dict_int, reject maxlen settings less than one

Changes

In contrib/dict_int, reject maxlen settings less than one (Tomas Vondra)

This prevents a possible crash with silly settings for that parameter.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsDisallow NULL category values in contrib/tablefunc's crosstab() function

Changes

Disallow NULL category values in contrib/tablefunc's crosstab() function (Joe Conway)

This case never worked usefully, and it would crash on some platforms.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsMark some timeout and statistics-tracking GUC variables as PGDLLIMPORT, to allow extensions to access them on Windows

Changes

Mark some timeout and statistics-tracking GUC variables as PGDLLIMPORT, to allow extensions to access them on Windows (Pascal Legrand)

This applies to lock_timeout, statement_timeout, track_activities, track_counts, and track_functions.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

Bug fixesFix race condition that led to delayed delivery of interprocess signals on Windows

Changes

Fix race condition that led to delayed delivery of interprocess signals on Windows (Amit Kapila)

This caused visible timing oddities in NOTIFY, and perhaps other misbehavior.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

ImprovementsOn Windows, retry a few times after an ERROR_ACCESS_DENIED file access failure

Changes

On Windows, retry a few times after an ERROR_ACCESS_DENIED file access failure (Alexander Lakhin, Tom Lane)

This helps cope with cases where a file open attempt fails because the targeted file is flagged for deletion but not yet actually gone. pg_ctl, for example, frequently failed with such an error when probing to see if the postmaster had shut down yet.

Related records (5)

“Same change” requires complete matching evidence. “Related commits” can cover independent changes, a partial backport, or a follow-up correction; each release keeps its own explanation.

How is this comparison generated?

The comparison follows PostgreSQL release notes from just after the source through the target version. For a major upgrade, maintenance releases from each older branch are included only up to the next major release date, and never after the target date. A major version such as 18 means its initial release, 18.0. Previews and development snapshots are labeled separately.

Entries come from the original English manuals. Release coverage and commit evidence are verified against upstream sources. Every entry retains its complete explanation and source link. Categories aid browsing; read the full notes for impact, conditions, and migration steps.

Fixes can be backported to several branches. Confirmed duplicates are merged conservatively, with every branch explanation retained. A note describing several independent fixes is excluded only when all are already present in the source. Major-release features remain distinct from related maintenance patches unless their complete original descriptions match. Uncertain matches are retained. This is a release-note history, not an exhaustive comparison of compiled binaries.

CVE results are calculated independently from the PostgreSQL security registry and vulnerability records. A CVE counts as gained protection only when the source is affected and the target is fixed or unaffected. Remaining vulnerabilities are listed separately. Security entries and distinct CVEs are counted separately.

Interaction inspired by pgversions.com and pgversionreport. Content comes from PostgreSQL release notes. See the release notes archive.