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POSTGRESQL · VERSION COMPARE
All features, fixes, and compatibility notes in this release, with related records from other versions.
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
2013-12-05
9.1.11 HistoricalSupport ends 2016-10-27
A dump/restore is not required for those running 9.1.X.
However, this release corrects a number of potential data corruption issues. See the first two changelog entries below to find out whether your installation has been affected and what steps you can take if so.
Also, if you are upgrading from a version earlier than 9.1.9, see Section E.16.
Changes
Fix VACUUM's tests to see whether it can update relfrozenxid (Andres Freund)
In some cases VACUUM (either manual or autovacuum) could incorrectly advance a table's relfrozenxid value, allowing tuples to escape freezing, causing those rows to become invisible once 2^31 transactions have elapsed. The probability of data loss is fairly low since multiple incorrect advancements would need to happen before actual loss occurs, but it's not zero. Users upgrading from releases 9.0.4 or 8.4.8 or earlier are not affected, but all later versions contain the bug.
The issue can be ameliorated by, after upgrading, vacuuming all tables in all databases while having vacuum_freeze_table_age set to zero. This will fix any latent corruption but will not be able to fix all pre-existing data errors. However, an installation can be presumed safe after performing this vacuuming if it has executed fewer than 2^31 update transactions in its lifetime (check this with SELECT txid_current() < 2^31).
“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.
Changes
Fix initialization of pg_clog and pg_subtrans during hot standby startup (Andres Freund, Heikki Linnakangas)
This bug can cause data loss on standby servers at the moment they start to accept hot-standby queries, by marking committed transactions as uncommitted. The likelihood of such corruption is small unless, at the time of standby startup, the primary server has executed many updating transactions since its last checkpoint. Symptoms include missing rows, rows that should have been deleted being still visible, and obsolete versions of updated rows being still visible alongside their newer versions.
This bug was introduced in versions 9.3.0, 9.2.5, 9.1.10, and 9.0.14. Standby servers that have only been running earlier releases are not at risk. It's recommended that standby servers that have ever run any of the buggy releases be re-cloned from the primary (e.g., with a new base backup) after upgrading.
“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.
Changes
Truncate pg_multixact contents during WAL replay (Andres Freund)
This avoids ever-increasing disk space consumption in standby servers.
“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.
Changes
Fix race condition in GIN index posting tree page deletion (Heikki Linnakangas)
This could lead to transient wrong answers or query failures.
“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.
Changes
Avoid flattening a subquery whose SELECT list contains a volatile function wrapped inside a sub-SELECT (Tom Lane)
This avoids unexpected results due to extra evaluations of the volatile function.
“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.
Changes
Fix planner's processing of non-simple-variable subquery outputs nested within outer joins (Tom Lane)
This error could lead to incorrect plans for queries involving multiple levels of subqueries within JOIN syntax.
“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.
Changes
Fix incorrect generation of optimized MIN()/MAX() plans for inheritance trees (Tom Lane)
The planner could fail in cases where the MIN()/MAX() argument was an expression rather than a simple variable.
“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.
Changes
Fix premature deletion of temporary files (Andres Freund)
“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.
Changes
Fix possible read past end of memory in rule printing (Peter Eisentraut)
“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.
Changes
Fix array slicing of int2vector and oidvector values (Tom Lane)
Expressions of this kind are now implicitly promoted to regular int2 or oid arrays.
“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.
Changes
Fix incorrect behaviors when using a SQL-standard, simple GMT offset timezone (Tom Lane)
In some cases, the system would use the simple GMT offset value when it should have used the regular timezone setting that had prevailed before the simple offset was selected. This change also causes the timeofday function to honor the simple GMT offset zone.
“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.
Changes
Prevent possible misbehavior when logging translations of Windows error codes (Tom Lane)
“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.
Changes
Properly quote generated command lines in pg_ctl (Naoya Anzai and Tom Lane)
This fix applies only to Windows.
“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.
Changes
Fix pg_dumpall to work when a source database sets default_transaction_read_only via ALTER DATABASE SET (Kevin Grittner)
Previously, the generated script would fail during restore.
“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.
Changes
Make ecpg search for quoted cursor names case-sensitively (Zoltán Böszörményi)
“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.
Changes
Fix ecpg's processing of lists of variables declared varchar (Zoltán Böszörményi)
“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.
Changes
Make contrib/lo defend against incorrect trigger definitions (Marc Cousin)
“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.
Changes
Update time zone data files to tzdata release 2013h for DST law changes in Argentina, Brazil, Jordan, Libya, Liechtenstein, Morocco, and Palestine. Also, new timezone abbreviations WIB, WIT, WITA for Indonesia.
“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.
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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.