E.4. Release 18.1
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## E.4. Release 18.1 #

Release date: 2025-11-13

This release contains a variety of fixes from 18.0. For information about new features in major release 18, see Section E.5.

### E.4.1. Migration to Version 18.1 #

A dump/restore is not required for those running 18.X.

### E.4.2. Changes #

- Check for `CREATE` privileges on the schema in `CREATE STATISTICS` (Jelte Fennema-Nio) §

  This omission allowed table owners to create statistics in any schema, potentially leading to unexpected naming conflicts.

  The PostgreSQL Project thanks Jelte Fennema-Nio for reporting this problem. (CVE-2025-12817)

- Avoid integer overflow in allocation-size calculations within libpq (Jacob Champion) §

  Several places in libpq were not sufficiently careful about computing the required size of a memory allocation. Sufficiently large inputs could cause integer overflow, resulting in an undersized buffer, which would then lead to writing past the end of the buffer.

  The PostgreSQL Project thanks Aleksey Solovev of Positive Technologies for reporting this problem. (CVE-2025-12818)

- Prevent “unrecognized node type” errors when a SQL/JSON function such as `JSON_VALUE` has a `DEFAULT` clause containing a `COLLATE` expression (Jian He) § §

- Avoid incorrect optimization of variable-free `HAVING` clauses with grouping sets (Richard Guo) § §

- Do not use parallelism in hash right semi joins (Richard Guo) §

  The case does not work reliably due to a race condition in updating the join's shared hash table.

- Avoid possible division-by-zero when creating ordered-append plans (Richard Guo) §

  This mistake could result in incorrect selection of the cheapest path, or in an assertion failure in debug builds.

- Fix planner failure with index types that can do ordered access but not index-only scans (Maxime Schoemans) §

  This oversight resulted in errors like “no data returned for index-only scan”. The case does not arise with any in-core index type, but some extensions encountered the problem.

- Remove faulty assertion in btree index cleanup (Peter Geoghegan) §

- Avoid possible out-of-memory or “invalid memory alloc request size” failures during parallel GIN index build (Tomas Vondra) §

- Ensure that BRIN autosummarization provides a snapshot for index expressions that need one (Álvaro Herrera) § §

  Previously, autosummarization would fail for such indexes, and then leave placeholder index tuples behind, causing the index to bloat over time.

- Fix integer-overflow hazard in BRIN index scans when the table contains close to 232 pages (Sunil S) §

  This oversight could result in an infinite loop or scanning of unneeded table pages.

- Fix incorrect zero-extension of stored values in JIT-generated tuple deforming code (David Rowley) §

  When not using JIT, the equivalent code does sign-extension not zero-extension, leading to a different Datum representation of small integer data types. This inconsistency was masked in most cases, but it is known to lead to “could not find memoization table entry” errors when using Memoize plan nodes, and there might be other symptoms.

- Fix rare crash when processing hashed `GROUPING SETS` queries (David Rowley) §

- Repair faulty hash-table-size-choosing logic in hash joins (Tomas Vondra) §

  Hash joins sometimes used more memory than intended, or failed to divide it in an efficient way.

- Improve relation lookup logic in statistics manipulation functions (Nathan Bossart) § §

  Fix `pg_restore_relation_stats()`, `pg_clear_relation_stats()`, `pg_restore_attribute_stats()`, and `pg_clear_attribute_stats()` to check privileges before acquiring lock on the target relation rather than after.

- Fix incorrect logic for caching result-relation information for triggers (David Rowley, Amit Langote) §

  In cases where partitions' column sets aren't physically identical to their parent partitioned tables' column sets, this oversight could lead to crashes.

- Fix crash during EvalPlanQual rechecks on partitioned tables (David Rowley, Amit Langote) §

- Fix EvalPlanQual handling of foreign or custom joins that do not have an alternative local-join plan prepared for EPQ (Masahiko Sawada, Etsuro Fujita) §

  In such cases the foreign or custom access method should be invoked normally, but that did not happen, typically leading to a crash.

- Avoid duplicating hash partition constraints during `DETACH CONCURRENTLY` (Haiyang Li) §

  `ALTER TABLE DETACH PARTITION CONCURRENTLY` was written to add a copy of the partitioning constraint to the now-detached partition. This was misguided, partially because non-concurrent `DETACH` doesn't do that, but mostly because in the case of hash partitioning the constraint expression contains references to the parent table's OID. That causes problems during dump/restore, or if the parent table is dropped after `DETACH`. In v19 and later, we'll no longer create any such copied constraints at all. In released branches, to minimize the risk of unforeseen consequences, only skip adding a copied constraint if it is for hash partitioning.

- Disallow generated columns in partition keys (Jian He, Ashutosh Bapat) §

  This was already not allowed, but the check missed some cases, such as where the column reference is implicit in a whole-row reference.

- Disallow generated columns in `COPY ... FROM ... WHERE` clauses (Peter Eisentraut, Jian He) §

  Previously, incorrect behavior or an obscure error message resulted from attempting to reference such a column, since generated columns have not yet been computed at the point where `WHERE` filtering is done.

- Prevent setting a column as identity if it has a not-null constraint but the constraint is marked as invalid (Jian He) §

  Identity columns must be not-null, but the check for that missed this edge case.

- Avoid potential use-after-free in parallel vacuum (Kevin Oommen Anish) §

  This bug seems to have no consequences in standard builds, but it's theoretically a hazard.

- Fix visibility checking for statistics objects in `pg_temp` (Noah Misch) §

  A statistics object located in a temporary schema cannot be named without schema qualification, but `pg_statistics_obj_is_visible()` missed that memo and could return “true” regardless. In turn, functions such as `pg_describe_object()` could fail to schema-qualify the object's name as expected.

- Fix minor memory leak during WAL replay of database creation (Nathan Bossart) §

- Fix incorrect reporting of replication lag in `pg_stat_replication` view (Fujii Masao) §

  If any standby server's replay LSN stopped advancing, the `write_lag` and `flush_lag` columns would eventually stop updating.

- Avoid duplicative log messages about invalid `primary_slot_name` settings (Fujii Masao) §

- Avoid failures when `synchronized_standby_slots` references nonexistent replication slots (Shlok Kyal) §

- Remove the unfinished slot state file after failing to write a replication slot's state to disk (Michael Paquier) §

  Previously, a failure such as out-of-disk-space resulted in leaving a temporary `state.tmp` file behind. That's problematic because it would block all subsequent attempts to write the state, requiring manual intervention to clean up.

- Fix mishandling of lock timeout signals in parallel apply workers for logical replication (Hayato Kuroda) §

  The same signal number was being used for both worker shutdown and lock timeout, leading to confusion.

- Avoid unwanted WAL receiver shutdown when switching from streaming to archive WAL source (Xuneng Zhou) §

  During a timeline change, a standby server's WAL receiver should remain alive, waiting for a new WAL streaming start point. Instead it was repeatedly shutting down and immediately getting restarted, which could confuse status monitoring code.

- Fix use-after-free issue in the relation synchronization cache maintained by the pgoutput logical decoding plugin (Vignesh C, Masahiko Sawada) §

  An error during logical decoding could result in crashes in subsequent logical decoding attempts in the same session. The case is only reachable when pgoutput is invoked via SQL functions.

- Avoid unnecessary invalidation of logical replication slots (Bertrand Drouvot) §

- Re-establish special case for `C` collation in locale setup (Jeff Davis) §

  This fixes a regression in access to shared catalogs early in backend startup, before a database has been selected. It is not known to be a problem for any core PostgreSQL code, but some extensions were broken.

- Fix incorrect printing of messages about failures in checking whether the user has Windows administrator privilege (Bryan Green) §

  This code would have crashed or at least printed garbage. No such cases have been reported though, indicating that failure of these system calls is extremely rare.

- Avoid crash when attempting to test PostgreSQL with certain libsanitizer options (Emmanuel Sibi, Jacob Champion) §

- Fix false memory-context-checking warnings in debug builds on 64-bit Windows (David Rowley) §

- Correctly handle `GROUP BY DISTINCT` in PL/pgSQL assignment statements (Tom Lane) §

  The parser failed to record the `DISTINCT` option in this context, so that the command would act as if it were plain `GROUP BY`.

- Avoid leaking memory when handling a SQL error within PL/Python (Tom Lane) §

  This fixes a session-lifespan memory leak introduced in our previous minor releases.

- Fix libpq's handling of socket-related errors on Windows within its GSSAPI logic (Ning Wu, Tom Lane) §

  The code for encrypting/decrypting transmitted data using GSSAPI did not correctly recognize error conditions on the connection socket, since Windows reports those differently than other platforms. This led to failure to make such connections on Windows.

- Fix dumping of non-inherited not-null constraints on inherited table columns (Dilip Kumar) §

  pg_dump failed to preserve such constraints when dumping from a pre-v18 server.

- Fix pg_dump's sorting of foreign key constraints (Álvaro Herrera) §

  Ensure consistent ordering of these database objects, as was already done for other object types.

- Fix assorted errors in the data compression logic in pg_dump and pg_restore (Daniel Gustafsson, Tom Lane) § § §

  Error checking was missing or incorrect in several places, and there were also portability issues that would manifest on big-endian hardware. These problems had been missed because this code is only used to read compressed TOC files within directory-format dumps. pg_dump never produces such a dump; the case can be reached only by manually compressing the TOC file after the fact, which is a supported thing to do but very uncommon.

- Fix pgbench to error out cleanly if a `COPY` operation is started (Anthonin Bonnefoy) §

  pgbench doesn't intend to support this case, but previously it went into an infinite loop.

- Fix pgbench's reporting of multiple errors (Yugo Nagata) §

  In cases where two successive `PQgetResult` calls both fail, pgbench might report the wrong error message.

- In pgbench, fix faulty assertion about errors in pipeline mode (Yugo Nagata) §

- Fix per-file memory leakage in pg_combinebackup (Tom Lane) §

- Ensure that `contrib/pg_buffercache` functions can be canceled (Satyanarayana Narlapuram, Yuhang Qiu) § §

  Some code paths were capable of running for a long time without checking for interrupts.

- Fix `contrib/pg_prewarm`'s privilege checks for indexes (Ayush Vatsa, Nathan Bossart) § §

  `pg_prewarm()` requires `SELECT` privilege on relations to be prewarmed. However, since indexes have no SQL privileges of their own, this resulted in non-superusers being unable to prewarm indexes. Instead, check for `SELECT` privilege on the index's table.

- In `contrib/pg_stat_statements`, avoid crash when two or more constants are marked as having the same location in the SQL statement text (Sami Imseih, Dmitry Dolgov) §

- Make `contrib/pgstattuple` more robust about empty or invalid index pages (Nitin Motiani) §

  Count all-zero pages as free space, and ignore pages that are invalid according to a check of the page's special-space size. The code for btree indexes already counted all-zero pages as free, but the hash and gist code would error out, which has been found to be much less user-friendly. Similarly, make all three cases agree on ignoring corrupted pages rather than throwing errors.

- Harden our read and write barrier macros to satisfy Clang (Thomas Munro) §

  We supposed that `__atomic_thread_fence()` is a sufficient barrier to prevent the C compiler from re-ordering memory accesses around it, but it appears that that's not true for Clang, allowing it to generate incorrect code for at least RISC-V, MIPS, and LoongArch machines. Add explicit compiler barriers to fix that.

- Fix PGXS build infrastructure to support building NLS `po` files for extensions (Ryo Matsumura) §

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