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2024-11-08Disallow partitionwise join when collations don't matchAmit Langote
If the collation of any join key column doesn’t match the collation of the corresponding partition key, partitionwise joins can yield incorrect results. For example, rows that would match under the join key collation might be located in different partitions due to the partitioning collation. In such cases, a partitionwise join would yield different results from a non-partitionwise join, so disallow it in such cases. Reported-by: Tender Wang <tndrwang@gmail.com> Author: Jian He <jian.universality@gmail.com> Reviewed-by: Tender Wang <tndrwang@gmail.com> Reviewed-by: Junwang Zhao <zhjwpku@gmail.com> Discussion: https://postgr.es/m/CAHewXNno_HKiQ6PqyLYfuqDtwp7KKHZiH1J7Pqyz0nr+PS2Dwg@mail.gmail.com Backpatch-through: 12
2024-11-08Disallow partitionwise grouping when collations don't matchAmit Langote
If the collation of any grouping column doesn’t match the collation of the corresponding partition key, partitionwise grouping can yield incorrect results. For example, rows that would be grouped under the grouping collation may end up in different partitions under the partitioning collation. In such cases, full partitionwise grouping would produce results that differ from those without partitionwise grouping, so disallowed that. Partial partitionwise aggregation is still allowed, as the Finalize step reconciles partition-level aggregates with grouping requirements across all partitions, ensuring that the final output remains consistent. This commit also fixes group_by_has_partkey() by ensuring the RelabelType node is stripped from grouping expressions when matching them to partition key expressions to avoid false mismatches. Bug: #18568 Reported-by: Webbo Han <1105066510@qq.com> Author: Webbo Han <1105066510@qq.com> Reviewed-by: Tender Wang <tndrwang@gmail.com> Reviewed-by: Aleksander Alekseev <aleksander@timescale.com> Reviewed-by: Jian He <jian.universality@gmail.com> Discussion: https://postgr.es/m/18568-2a9afb6b9f7e6ed3@postgresql.org Discussion: https://postgr.es/m/tencent_9D9103CDA420C07768349CC1DFF88465F90A@qq.com Discussion: https://postgr.es/m/CAHewXNno_HKiQ6PqyLYfuqDtwp7KKHZiH1J7Pqyz0nr+PS2Dwg@mail.gmail.com Backpatch-through: 12
2024-11-08Message style improvementPeter Eisentraut
Backpatch the part of edee0c621de that applies to a90bdd7a44d, which was also backpatched. That way, the message is consistent in all branches.
2024-11-08Replace pgwin32_is_junction() with lstat().Thomas Munro
Now that lstat() reports junction points with S_IFLNK/S_ISLINK(), and unlink() can unlink them, there is no need for conditional code for Windows in a few places. That was expressed by testing for WIN32 or S_ISLNK, which we can now constant-fold. The coding around pgwin32_is_junction() was a bit suspect anyway, as we never checked for errors, and we also know that errors can be spuriously reported because of transient sharing violations on this OS. The lstat()-based code has handling for that. This also reverts 4fc6b6ee on master only. That was done because lstat() didn't previously work for symlinks (junction points), but now it does. Tested-by: Andrew Dunstan <andrew@dunslane.net> Discussion: https://postgr.es/m/CA%2BhUKGLfOOeyZpm5ByVcAt7x5Pn-%3DxGRNCvgiUPVVzjFLtnY0w%40mail.gmail.com (cherry picked from commit 5fc88c5d53e43fa7dcea93499d230a0bf70f4f77) Author: Thomas Munro <tmunro@postgresql.org> Author: Alexandra Wang <alexandra.wang.oss@gmail.com>
2024-11-08Check for STATUS_DELETE_PENDING on Windows.Thomas Munro
1. Update our open() wrapper to check for NT's STATUS_DELETE_PENDING and translate it to Unix-like errors. This is done with RtlGetLastNtStatus(), which is dynamically loaded from ntdll. A new file win32ntdll.c centralizes lookup of NT functions, in case we decide to add more in the future. 2. Remove non-working code that was trying to do something similar for stat(), and just reuse the open() wrapper code. As a side effect, stat() also gains resilience against "sharing violation" errors. 3. Since stat() is used very early in process startup, remove the requirement that the Win32 signal event has been created before pgwin32_open_handle() is reached. Instead, teach pg_usleep() to fall back to a non-interruptible sleep if reached before the signal event is available. This could be back-patched, but for now it's in master only. The problem has apparently been with us for a long time and generated only a few complaints. Proposed patches trigger it more often, which led to this investigation and fix. Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Alexander Lakhin <exclusion@gmail.com> Reviewed-by: Juan José Santamaría Flecha <juanjo.santamaria@gmail.com> Discussion: https://postgr.es/m/CA%2BhUKGJz_pZTF9mckn6XgSv69%2BjGwdgLkxZ6b3NWGLBCVjqUZA%40mail.gmail.com (cherry picked from commit e2f0f8ed251d02c1eda79e1ca3cb3db2681e7a86) Author: Thomas Munro <tmunro@postgresql.org> Author: Alexandra Wang <alexandra.wang.oss@gmail.com>
2024-11-06Monkey-patch LLVM code to fix ARM relocation bug.Thomas Munro
Supply a new memory manager for RuntimeDyld, to avoid crashes in generated code caused by memory placement that can overflow a 32 bit data type. This is a drop-in replacement for the llvm::SectionMemoryManager class in the LLVM library, with Michael Smith's proposed fix from https://www.github.com/llvm/llvm-project/pull/71968. We hereby slurp it into our own source tree, after moving into a new namespace llvm::backport and making some minor adjustments so that it can be compiled with older LLVM versions as far back as 12. It's harder to make it work on even older LLVM versions, but it doesn't seem likely that people are really using them so that is not investigated for now. The problem could also be addressed by switching to JITLink instead of RuntimeDyld, and that is the LLVM project's recommended solution as the latter is about to be deprecated. We'll have to do that soon enough anyway, and then when the LLVM version support window advances far enough in a few years we'll be able to delete this code. Unfortunately that wouldn't be enough for PostgreSQL today: in most relevant versions of LLVM, JITLink is missing or incomplete. Several other projects have already back-ported this fix into their fork of LLVM, which is a vote of confidence despite the lack of commit into LLVM as of today. We don't have our own copy of LLVM so we can't do exactly what they've done; instead we have a copy of the whole patched class so we can pass an instance of it to RuntimeDyld. The LLVM project hasn't chosen to commit the fix yet, and even if it did, it wouldn't be back-ported into the releases of LLVM that most of our users care about, so there is not much point in waiting any longer for that. If they make further changes and commit it to LLVM 19 or 20, we'll still need this for older versions, but we may want to resynchronize our copy and update some comments. The changes that we've had to make to our copy can be seen by diffing our SectionMemoryManager.{h,cpp} files against the ones in the tree of the pull request. Per the LLVM project's license requirements, a copy is in SectionMemoryManager.LICENSE. This should fix the spate of crash reports we've been receiving lately from users on large memory ARM systems. Back-patch to all supported releases. Co-authored-by: Thomas Munro <thomas.munro@gmail.com> Co-authored-by: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com> Reviewed-by: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com> Reviewed-by: Daniel Gustafsson <daniel@yesql.se> (license aspects) Reported-by: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com> Discussion: https://postgr.es/m/CAO6_Xqr63qj%3DSx7HY6ZiiQ6R_JbX%2B-p6sTPwDYwTWZjUmjsYBg%40mail.gmail.com
2024-11-02Suppress new "may be used uninitialized" warning.Noah Misch
Buildfarm member mamba fails to deduce that the function never uses this variable without initializing it. Back-patch to v12, like commit b412f402d1e020c5dac94f3bf4a005db69519b99.
2024-11-02Move I/O before the index_update_stats() buffer lock region.Noah Misch
Commit a07e03fd8fa7daf4d1356f7cb501ffe784ea6257 enlarged the work done here under the pg_class heap buffer lock. Two preexisting actions are best done before holding that lock. Both RelationGetNumberOfBlocks() and visibilitymap_count() do I/O, and the latter might exclusive-lock a visibility map buffer. Moving these reduces contention and risk of undetected LWLock deadlock. Back-patch to v12, like that commit. Discussion: https://postgr.es/m/20241031200139.b4@rfd.leadboat.com
2024-11-02Revert "For inplace update, send nontransactional invalidations."Noah Misch
This reverts commit 95c5acb3fc261067ab65ddc0b2dca8e162f09442 (v17) and counterparts in each other non-master branch. If released, that commit would have caused a worst-in-years minor release regression, via undetected LWLock self-deadlock. This commit and its self-deadlock fix warrant more bake time in the master branch. Reported by Alexander Lakhin. Discussion: https://postgr.es/m/10ec0bc3-5933-1189-6bb8-5dec4114558e@gmail.com
2024-11-02Revert "WAL-log inplace update before revealing it to other sessions."Noah Misch
This reverts commit bfd5c6e279c8e1702eea882439dc7ebdf4d4b3a5 (v17) and counterparts in each other non-master branch. This unblocks reverting a commit on which it depends. Discussion: https://postgr.es/m/10ec0bc3-5933-1189-6bb8-5dec4114558e@gmail.com
2024-10-29Unpin buffer before inplace update waits for an XID to end.Noah Misch
Commit a07e03fd8fa7daf4d1356f7cb501ffe784ea6257 changed inplace updates to wait for heap_update() commands like GRANT TABLE and GRANT DATABASE. By keeping the pin during that wait, a sequence of autovacuum workers and an uncommitted GRANT starved one foreground LockBufferForCleanup() for six minutes, on buildfarm member sarus. Prevent, at the cost of a bit of complexity. Back-patch to v12, like the earlier commit. That commit and heap_inplace_lock() have not yet appeared in any release. Discussion: https://postgr.es/m/20241026184936.ae.nmisch@google.com
2024-10-25WAL-log inplace update before revealing it to other sessions.Noah Misch
A buffer lock won't stop a reader having already checked tuple visibility. If a vac_update_datfrozenid() and then a crash happened during inplace update of a relfrozenxid value, datfrozenxid could overtake relfrozenxid. That could lead to "could not access status of transaction" errors. Back-patch to v12 (all supported versions). In v14 and earlier, this also back-patches the assertion removal from commit 7fcf2faf9c7dd473208fd6d5565f88d7f733782b. Discussion: https://postgr.es/m/20240620012908.92.nmisch@google.com
2024-10-25For inplace update, send nontransactional invalidations.Noah Misch
The inplace update survives ROLLBACK. The inval didn't, so another backend's DDL could then update the row without incorporating the inplace update. In the test this fixes, a mix of CREATE INDEX and ALTER TABLE resulted in a table with an index, yet relhasindex=f. That is a source of index corruption. Back-patch to v12 (all supported versions). The back branch versions don't change WAL, because those branches just added end-of-recovery SIResetAll(). All branches change the ABI of extern function PrepareToInvalidateCacheTuple(). No PGXN extension calls that, and there's no apparent use case in extensions. Reviewed by Nitin Motiani and (in earlier versions) Andres Freund. Discussion: https://postgr.es/m/20240523000548.58.nmisch@google.com
2024-10-25At end of recovery, reset all sinval-managed caches.Noah Misch
An inplace update's invalidation messages are part of its transaction's commit record. However, the update survives even if its transaction aborts or we stop recovery before replaying its transaction commit. After recovery, a backend that started in recovery could update the row without incorporating the inplace update. That could result in a table with an index, yet relhasindex=f. That is a source of index corruption. This bulk invalidation avoids the functional consequences. A future change can fix the !RecoveryInProgress() scenario without changing the WAL format. Back-patch to v17 - v12 (all supported versions). v18 will instead add invalidations to WAL. Discussion: https://postgr.es/m/20240618152349.7f.nmisch@google.com
2024-10-24Stop reading uninitialized memory in heap_inplace_lock().Noah Misch
Stop computing a never-used value. This removes the read; the read had no functional implications. Back-patch to v12, like commit a07e03fd8fa7daf4d1356f7cb501ffe784ea6257. Reported by Alexander Lakhin. Discussion: https://postgr.es/m/6c92f59b-f5bc-e58c-9bdd-d1f21c17c786@gmail.com
2024-10-23Remove unnecessary word in a commentAmit Langote
Relations opened by the executor are only closed once in ExecCloseRangeTableRelations(), so the word "again" in the comment for ExecGetRangeTableRelation() is misleading and unnecessary. Discussion: https://postgr.es/m/CA+HiwqHnw-zR+u060i3jp4ky5UR0CjByRFQz50oZ05de7wUg=Q@mail.gmail.com Backpatch-through: 12
2024-10-22Restructure foreign key handling code for ATTACH/DETACHÁlvaro Herrera
... to fix bugs when the referenced table is partitioned. The catalog representation we chose for foreign keys connecting partitioned tables (in commit f56f8f8da6af) is inconvenient, in the sense that a standalone table has a different way to represent the constraint when referencing a partitioned table, than when the same table becomes a partition (and vice versa). Because of this, we need to create additional catalog rows on detach (pg_constraint and pg_trigger), and remove them on attach. We were doing some of those things, but not all of them, leading to missing catalog rows in certain cases. The worst problem seems to be that we are missing action triggers after detaching a partition, which means that you could update/delete rows from the referenced partitioned table that still had referencing rows on that table, the server failing to throw the required errors. !!! Note that this means existing databases with FKs that reference partitioned tables might have rows that break relational integrity, on tables that were once partitions on the referencing side of the FK. Another possible problem is that trying to reattach a table that had been detached would fail indicating that internal triggers cannot be found, which from the user's point of view is nonsensical. In branches 15 and above, we fix this by creating a new helper function addFkConstraint() which is in charge of creating a standalone pg_constraint row, and repurposing addFkRecurseReferencing() and addFkRecurseReferenced() so that they're only the recursive routine for each side of the FK, and they call addFkConstraint() to create pg_constraint at each partitioning level and add the necessary triggers. These new routines can be used during partition creation, partition attach and detach, and foreign key creation. This reduces redundant code and simplifies the flow. In branches 14 and 13, we have a much simpler fix that consists on simply removing the constraint on detach. The reason is that those branches are missing commit f4566345cf40, which reworked the way this works in a way that we didn't consider back-patchable at the time. We opted to leave branch 12 alone, because it's different from branch 13 enough that the fix doesn't apply; and because it is going in EOL mode very soon, patching it now might be worse since there's no way to undo the damage if it goes wrong. Existing databases might need to be repaired. In the future we might want to rethink the catalog representation to avoid this problem, but for now the code seems to do what's required to make the constraints operate correctly. Co-authored-by: Jehan-Guillaume de Rorthais <jgdr@dalibo.com> Co-authored-by: Tender Wang <tndrwang@gmail.com> Co-authored-by: Alvaro Herrera <alvherre@alvh.no-ip.org> Reported-by: Guillaume Lelarge <guillaume@lelarge.info> Reported-by: Jehan-Guillaume de Rorthais <jgdr@dalibo.com> Reported-by: Thomas Baehler (SBB CFF FFS) <thomas.baehler2@sbb.ch> Discussion: https://postgr.es/m/20230420144344.40744130@karst Discussion: https://postgr.es/m/20230705233028.2f554f73@karst Discussion: https://postgr.es/m/GVAP278MB02787E7134FD691861635A8BC9032@GVAP278MB0278.CHEP278.PROD.OUTLOOK.COM Discussion: https://postgr.es/m/18541-628a61bc267cd2d3@postgresql.org
2024-10-21Fix wrong assertion and poor error messages in "COPY (query) TO".Tom Lane
If the query is rewritten into a NOTIFY command by a DO INSTEAD rule, we'd get an assertion failure, or in non-assert builds issue a rather confusing error message. Improve that. Also fix a longstanding grammar mistake in a nearby error message. Per bug #18664 from Alexander Lakhin. Back-patch to all supported branches. Tender Wang and Tom Lane Discussion: https://postgr.es/m/18664-ffd0ebc2386598df@postgresql.org
2024-10-21Fix race condition in committing a serializable transactionHeikki Linnakangas
The finished transaction list can contain XIDs that are older than the serializable global xmin. It's a short-lived state; ClearOldPredicateLocks() removes any such transactions from the list, and it's called whenever the global xmin advances. But if another backend calls SummarizeOldestCommittedSxact() in that window, it will call SerialAdd() on an XID that's older than the global xmin, or if there are no more transactions running, when global xmin is invalid. That trips the assertion in SerialAdd(). Fixes bug #18658 reported by Andrew Bille. Thanks to Alexander Lakhin for analysis. Backpatch to all versions. Discussion: https://www.postgresql.org/message-id/18658-7dab125ec688c70b%40postgresql.org
2024-10-17Fix extreme skew detection in Parallel Hash Join.Thomas Munro
After repartitioning the inner side of a hash join that would have exceeded the allowed size, we check if all the tuples from a parent partition moved to one child partition. That is evidence that it contains duplicate keys and later attempts to repartition will also fail, so we should give up trying to limit memory (for lack of a better fallback strategy). A thinko prevented the check from working correctly in partition 0 (the one that is partially loaded into memory already). After repartitioning, we should check for extreme skew if the *parent* partition's space_exhausted flag was set, not the child partition's. The consequence was repeated futile repartitioning until per-partition data exceeded various limits including "ERROR: invalid DSA memory alloc request size 1811939328", OS allocation failure, or temporary disk space errors. (We could also do something about some of those symptoms, but that's material for separate patches.) This problem only became likely when PostgreSQL 16 introduced support for Parallel Hash Right/Full Join, allowing NULL keys into the hash table. Repartitioning always leaves NULL in partition 0, no matter how many times you do it, because the hash value is all zero bits. That's unlikely for other hashed values, but they might still have caused wasted extra effort before giving up. Back-patch to all supported releases. Reported-by: Craig Milhiser <craig@milhiser.com> Reviewed-by: Andrei Lepikhov <lepihov@gmail.com> Discussion: https://postgr.es/m/CA%2BwnhO1OfgXbmXgC4fv_uu%3DOxcDQuHvfoQ4k0DFeB0Qqd-X-rQ%40mail.gmail.com
2024-10-16Further refine _SPI_execute_plan's rule for atomic execution.Tom Lane
Commit 2dc1deaea turns out to have been still a brick shy of a load, because CALL statements executing within a plpgsql exception block could still pass the wrong snapshot to stable functions within the CALL's argument list. That happened because standard_ProcessUtility forces isAtomicContext to true if IsTransactionBlock is true, which it always will be inside a subtransaction. Then ExecuteCallStmt would think it does not need to push a new snapshot --- but _SPI_execute_plan didn't do so either, since it thought it was in nonatomic mode. The best fix for this seems to be for _SPI_execute_plan to operate in atomic execution mode if IsSubTransaction() is true, even when the SPI context as a whole is non-atomic. This makes _SPI_execute_plan have the same rules about when non-atomic execution is allowed as _SPI_commit/_SPI_rollback have about when COMMIT/ROLLBACK are allowed, which seems appropriately symmetric. (If anyone ever tries to allow COMMIT/ROLLBACK inside a subtransaction, this would all need to be rethought ... but I'm unconvinced that such a thing could be logically consistent at all.) For further consistency, also check IsSubTransaction() in SPI_inside_nonatomic_context. That does not matter for its one present-day caller StartTransaction, which can't be reached inside a subtransaction. But if any other callers ever arise, they'd presumably want this definition. Per bug #18656 from Alexander Alehin. Back-patch to all supported branches, like previous fixes in this area. Discussion: https://postgr.es/m/18656-cade1780866ef66c@postgresql.org
2024-10-16Reduce memory block size for decoded tuple storage to 8kB.Masahiko Sawada
Commit a4ccc1cef introduced the Generation Context and modified the logical decoding process to use a Generation Context with a fixed block size of 8MB for storing tuple data decoded during logical decoding (i.e., rb->tup_context). Several reports have indicated that the logical decoding process can be terminated due to out-of-memory (OOM) situations caused by excessive memory usage in rb->tup_context. This issue can occur when decoding a workload involving several concurrent transactions, including a long-running transaction that modifies tuples. By design, the Generation Context does not free a memory block until all chunks within that block are released. Consequently, if tuples modified by the long-running transaction are stored across multiple memory blocks, these blocks remain allocated until the long-running transaction completes, leading to substantial memory fragmentation. The memory usage during logical decoding, tracked by rb->size, does not account for memory fragmentation, resulting in potentially much higher memory consumption than the value of the logical_decoding_work_mem parameter. Various improvement strategies were discussed in the relevant thread. This change reduces the block size of the Generation Context used in rb->tup_context from 8MB to 8kB. This modification significantly decreases the likelihood of substantial memory fragmentation occurring and is relatively straightforward to backport. Performance testing across multiple platforms has confirmed that this change will not introduce any performance degradation that would impact actual operation. Backport to all supported branches. Reported-by: Alex Richman, Michael Guissine, Avi Weinberg Reviewed-by: Amit Kapila, Fujii Masao, David Rowley Tested-by: Hayato Kuroda, Shlok Kyal Discussion: https://postgr.es/m/CAD21AoBTY1LATZUmvSXEssvq07qDZufV4AF-OHh9VD2pC0VY2A%40mail.gmail.com Backpatch-through: 12
2024-10-12Correctly identify which EC members are computable at a plan node.Tom Lane
find_computable_ec_member() had the wrong mental model of what its primary caller prepare_sort_from_pathkeys() would do with the selected EquivalenceClass member expression. We will not compute the EC expression in a plan node atop the one returning the passed-in targetlist; rather, the EC expression will be computed as an additional column of that targetlist. So any Var or quasi-Var used in the given tlist is also available to the EC expression. In simple cases this makes no difference because the given tlist is just a list of Vars or quasi-Vars --- but if we are considering an appendrel member produced by flattening a UNION ALL, the tlist may contain expressions, resulting in failure to match and a "could not find pathkey item to sort" error. To fix, we can flatten both the tlist and the EC members with pull_var_clause(), and then just check for subset-ness, so that the code is actually shorter than before. While this bug is quite old, the present patch only works back to v13. We could possibly make it work in v12 by back-patching parts of 375398244. On the whole though I don't like the risk/reward ratio of that idea. v12's final release is next month, meaning there would be no chance to correct matters if the patch causes a regression. Since this failure has escaped notice for 14 years, it's likely nobody will hit it in the field with v12. Per bug #18652 from Alexander Lakhin. Andrei Lepikhov and Tom Lane Discussion: https://postgr.es/m/18652-deaa782ebcca85d1@postgresql.org
2024-10-07Fix Y2038 issues with MyStartTime.Nathan Bossart
Several places treat MyStartTime as a "long", which is only 32 bits wide on some platforms. In reality, MyStartTime is a pg_time_t, i.e., a signed 64-bit integer. This will lead to interesting bugs on the aforementioned systems in 2038 when signed 32-bit integers are no longer sufficient to store Unix time (e.g., "pg_ctl start" hanging). To fix, ensure that MyStartTime is handled as a 64-bit value everywhere. (Of course, users will need to ensure that time_t is 64 bits wide on their system, too.) Co-authored-by: Max Johnson Discussion: https://postgr.es/m/CO1PR07MB905262E8AC270FAAACED66008D682%40CO1PR07MB9052.namprd07.prod.outlook.com Backpatch-through: 12
2024-10-07Fix fetching default toast value during decoding of in-progress transactions.Amit Kapila
During logical decoding of in-progress transactions, we perform the toast table scan while fetching the default toast value for an attribute. We forgot to initialize the flag during this scan to indicate that the system table scan is in progress. We need this flag to ensure that during logical decoding we never directly access the tableam or heap APIs because we check for concurrent aborts only in systable_* APIs. Reported-by: Alexander Lakhin Author: Takeshi Ideriha, Hou Zhijie Reviewed-by: Amit Kapila, Hou Zhijie Backpatch-through: 14 Discussion: https://postgr.es/m/18641-6687273b7f15269d@postgresql.org
2024-10-06Ignore not-yet-defined Portals in pg_cursors view.Tom Lane
pg_cursor() supposed that any Portal it finds in the hash table must have sourceText set up, but there's an edge case where that is not so. A newly-created Portal has sourceText = NULL, and that doesn't change until PortalDefineQuery is called. In SPI_cursor_open_internal, we perform GetCachedPlan between CreatePortal and PortalDefineQuery, and it's possible for user-defined code to execute during that planning and cause a fetch from the pg_cursors view, resulting in a null-pointer-dereference crash. (It looks like the same could happen in exec_bind_message, but I've not tried to provoke a failure there.) I considered trying to fix this by setting sourceText sooner, but there may be instances of this same calling pattern in extensions, and we couldn't be sure they'd get the memo promptly. It seems better to redefine pg_cursor as not showing Portals that have not yet had PortalDefineQuery called on them, which we can do by just skipping them if sourceText is still NULL. (Before a1c692358, pg_cursor would instead return a row with NULL in the statement column. We could revert to that behavior but it doesn't really seem like a better definition, especially since our documentation doesn't suggest that the column could be NULL.) Per report from PetSerAl. Back-patch to all supported branches. Discussion: https://postgr.es/m/CAKygsHTBXLXjwV43kpZa+Cs+XTiaeeJiZdL4cPBm9f4MTdw7wg@mail.gmail.com
2024-10-01Fix race condition in COMMIT PREPARED causing orphaned 2PC filesMichael Paquier
COMMIT PREPARED removes on-disk 2PC files near its end, but the state checked if a file is on-disk or not gets read from shared memory while not holding the two-phase state lock. Because of that, there was a small window where a second backend doing a PREPARE TRANSACTION could reuse the GlobalTransaction put back into the 2PC free list by the COMMIT PREPARED, overwriting the "ondisk" flag read afterwards by the COMMIT PREPARED to decide if its on-disk two-phase state file should be removed, preventing the file deletion. This commit fixes this issue so as the "ondisk" flag in the GlobalTransaction is read while holding the two-phase state lock, not from shared memory after its entry has been added to the free list. Orphaned two-phase state files flushed to disk after a checkpoint are discarded at the beginning of recovery. However, a truncation of pg_xact/ would make the startup process issue a FATAL when it cannot read the SLRU page holding the state of the transaction whose 2PC file was orphaned, which is a necessary step to decide if the 2PC file should be removed or not. Removing manually the file would be necessary in this case. Issue introduced by effe7d9552dd, so backpatch all the way down. Mea culpa. Author: wuchengwen Discussion: https://postgr.es/m/tencent_A7F059B5136A359625C7B2E4A386B3C3F007@qq.com Backpatch-through: 12
2024-09-29Remove NULL dereference from RenameRelationInternal().Noah Misch
Defect in last week's commit aac2c9b4fde889d13f859c233c2523345e72d32b, per Coverity. Reaching this would need catalog corruption. Back-patch to v12, like that commit.
2024-09-27Fix incorrect memory access in VACUUM FULL with invalid toast indexesMichael Paquier
An invalid toast index is skipped in reindex_relation(). These would be remnants of a failed REINDEX CONCURRENTLY and they should never been rebuilt as there can only be one valid toast index at a time. REINDEX_REL_SUPPRESS_INDEX_USE, used by CLUSTER and VACUUM FULL, needs to maintain a list of the indexes being processed. The list of indexes is retrieved from the relation cache, and includes invalid indexes. The code has missed that invalid toast indexes are ignored in reindex_relation() as this leads to a hard failure in reindex_index(), and they were left in the reindex pending list, making the list inconsistent when rechecked. The incorrect memory access was happening when scanning pg_class for the refresh of pg_database.datfrozenxid, when doing a scan of pg_class. This issue exists since REINDEX CONCURRENTLY exists, where invalid toast indexes can exist, so backpatch all the way down. Reported-by: Alexander Lakhin Author: Tender Wang Discussion: https://postgr.es/m/18630-9aed99c38830657d@postgresql.org Backpatch-through: 12
2024-09-24For inplace update durability, make heap_update() callers wait.Noah Misch
The previous commit fixed some ways of losing an inplace update. It remained possible to lose one when a backend working toward a heap_update() copied a tuple into memory just before inplace update of that tuple. In catalogs eligible for inplace update, use LOCKTAG_TUPLE to govern admission to the steps of copying an old tuple, modifying it, and issuing heap_update(). This includes MERGE commands. To avoid changing most of the pg_class DDL, don't require LOCKTAG_TUPLE when holding a relation lock sufficient to exclude inplace updaters. Back-patch to v12 (all supported versions). In v13 and v12, "UPDATE pg_class" or "UPDATE pg_database" can still lose an inplace update. The v14+ UPDATE fix needs commit 86dc90056dfdbd9d1b891718d2e5614e3e432f35, and it wasn't worth reimplementing that fix without such infrastructure. Reviewed by Nitin Motiani and (in earlier versions) Heikki Linnakangas. Discussion: https://postgr.es/m/20231027214946.79.nmisch@google.com
2024-09-24Fix data loss at inplace update after heap_update().Noah Misch
As previously-added tests demonstrated, heap_inplace_update() could instead update an unrelated tuple of the same catalog. It could lose the update. Losing relhasindex=t was a source of index corruption. Inplace-updating commands like VACUUM will now wait for heap_update() commands like GRANT TABLE and GRANT DATABASE. That isn't ideal, but a long-running GRANT already hurts VACUUM progress more just by keeping an XID running. The VACUUM will behave like a DELETE or UPDATE waiting for the uncommitted change. For implementation details, start at the systable_inplace_update_begin() header comment and README.tuplock. Back-patch to v12 (all supported versions). In back branches, retain a deprecated heap_inplace_update(), for extensions. Reported by Smolkin Grigory. Reviewed by Nitin Motiani, (in earlier versions) Heikki Linnakangas, and (in earlier versions) Alexander Lakhin. Discussion: https://postgr.es/m/CAMp+ueZQz3yDk7qg42hk6-9gxniYbp-=bG2mgqecErqR5gGGOA@mail.gmail.com
2024-09-24Warn if LOCKTAG_TUPLE is held at commit, under debug_assertions.Noah Misch
The current use always releases this locktag. A planned use will continue that intent. It will involve more areas of code, making unlock omissions easier. Warn under debug_assertions, like we do for various resource leaks. Back-patch to v12 (all supported versions), the plan for the commit of the new use. Reviewed by Heikki Linnakangas. Discussion: https://postgr.es/m/20240512232923.aa.nmisch@google.com
2024-09-17Don't enter parallel mode when holding interrupts.Noah Misch
Doing so caused the leader to hang in wait_event=ParallelFinish, which required an immediate shutdown to resolve. Back-patch to v12 (all supported versions). Francesco Degrassi Discussion: https://postgr.es/m/CAC-SaSzHUKT=vZJ8MPxYdC_URPfax+yoA1hKTcF4ROz_Q6z0_Q@mail.gmail.com
2024-09-18Add missing query ID reporting in extended query protocolMichael Paquier
This commit adds query ID reports for two code paths when processing extended query protocol messages: - When receiving a bind message, setting it to the first Query retrieved from a cached cache. - When receiving an execute message, setting it to the first PlannedStmt stored in a portal. An advantage of this method is that this is able to cover all the types of portals handled in the extended query protocol, particularly these two when the report done in ExecutorStart() is not enough (neither is an addition in ExecutorRun(), actually, for the second point): - Multiple execute messages, with multiple ExecutorRun(). - Portal with execute/fetch messages, like a query with a RETURNING clause and a fetch size that stores the tuples in a first execute message going though ExecutorStart() and ExecuteRun(), followed by one or more execute messages doing only fetches from the tuplestore created in the first message. This corresponds to the case where execute_is_fetch is set, for example. Note that the query ID reporting done in ExecutorStart() is still necessary, as an EXECUTE requires it. Query ID reporting is optimistic and more calls to pgstat_report_query_id() don't matter as the first report takes priority except if the report is forced. The comment in ExecutorStart() is adjusted to reflect better the reality with the extended query protocol. The test added in pg_stat_statements is a courtesy of Robert Haas. This uses psql's \bind metacommand, hence this part is backpatched down to v16. Reported-by: Kaido Vaikla, Erik Wienhold Author: Sami Imseih Reviewed-by: Jian He, Andrei Lepikhov, Michael Paquier Discussion: https://postgr.es/m/CA+427g8DiW3aZ6pOpVgkPbqK97ouBdf18VLiHFesea2jUk3XoQ@mail.gmail.com Discussion: https://postgr.es/m/CA+TgmoZxtnf_jZ=VqBSyaU8hfUkkwoJCJ6ufy4LGpXaunKrjrg@mail.gmail.com Discussion: https://postgr.es/m/1391613709.939460.1684777418070@office.mailbox.org Backpatch-through: 14
2024-09-15Replace usages of xmlXPathCompile() with xmlXPathCtxtCompile().Tom Lane
In existing releases of libxml2, xmlXPathCompile can be driven to stack overflow because it fails to protect itself against too-deeply-nested input. While there is an upstream fix as of yesterday, it will take years for that to propagate into all shipping versions. In the meantime, we can protect our own usages basically for free by calling xmlXPathCtxtCompile instead. (The actual bug is that libxml2 keeps its nesting counter in the xmlXPathContext, and its parsing code was willing to just skip counting nesting levels if it didn't have a context. So if we supply a context, all is well. It seems odd actually that it works at all to not supply a context, because this means that XPath parsing does not have access to XML namespace info. Apparently libxml2 never checks namespaces until runtime? Anyway, this seems like good future-proofing even if its only immediate effect is to dodge a bug.) Sadly, this hack only offers protection with libxml2 2.9.11 and newer. Before that there are multiple similar problems, so if you are processing untrusted XML it behooves you to get a newer version. But we have some pretty old libxml2 in the buildfarm, so it seems impractical to add a regression test to verify this fix. Per bug #18617 from Jingzhou Fu. Back-patch to all supported versions. Discussion: https://postgr.es/m/18617-1cee4d2ed1f4e7ae@postgresql.org Discussion: https://gitlab.gnome.org/GNOME/libxml2/-/issues/799
2024-09-13Allow _h_indexbuild() to be interrupted.Tom Lane
When we are building a hash index that is large enough to need pre-sorting (larger than either maintenance_work_mem or NBuffers), the initial sorting phase is interruptible, but the insertion phase wasn't. Add the missing CHECK_FOR_INTERRUPTS(). Per bug #18616 from Alexander Lakhin. Back-patch to all supported branches. Pavel Borisov Discussion: https://postgr.es/m/18616-acbb9e5caf41e964@postgresql.org
2024-09-11Remove incorrect Assert.Tom Lane
check_agglevels_and_constraints() asserted that if we find an aggregate function in an EXPR_KIND_FROM_SUBSELECT expression, the expression must be in a LATERAL subquery. Alexander Lakhin found a case where that's not so: because of the odd scoping rules for NEW/OLD within a rule, a reference to NEW/OLD could cause an aggregate to be considered top-level even though it's in an unmarked sub-select. The error message that would be thrown seems sufficiently on-point, so just remove the Assert. (Hence, this is not a bug for production builds.) This Assert was added by me in commit eaccfded9 (9.3 era). It looks like I put it in to cross-check that the new logic for detecting misplaced aggregates (using agglevelsup) caught the same cases that a previous check on p_lateral_active did. So there might have been some related misbehavior before eaccfded9 ... but that's very ancient history by now, so I didn't dig any deeper. Per bug #18608 from Alexander Lakhin. Back-patch to all supported branches. Discussion: https://postgr.es/m/18608-48de0717508ee429@postgresql.org
2024-09-09Fix waits of REINDEX CONCURRENTLY for indexes with predicates or expressionsMichael Paquier
As introduced by f9900df5f94, a REINDEX CONCURRENTLY job done for an index with predicates or expressions would set PROC_IN_SAFE_IC in its MyProc->statusFlags, causing it to be ignored by other concurrent operations. Such concurrent index rebuilds should never be ignored, as a predicate or an expression could call a user-defined function that accesses a different table than the table where the index is rebuilt. A test that uses injection points is added, backpatched down to 17. Michail has proposed a different test, but I have added something simpler with more coverage. Oversight in f9900df5f949. Author: Michail Nikolaev Discussion: https://postgr.es/m/CANtu0oj9A3kZVduFTG0vrmGnKB+DCHgEpzOp0qAyOgmks84j0w@mail.gmail.com Backpatch-through: 14
2024-08-30Clarify restrict_nonsystem_relation_kind description.Masahiko Sawada
This change improves the description of the restrict_nonsystem_relation_kind parameter in guc_table.c and the documentation for better clarity. Backpatch to 12, where this GUC parameter was introduced. Reviewed-by: Peter Eisentraut Discussion: https://postgr.es/m/6a96f1af-22b4-4a80-8161-1f26606b9ee2%40eisentraut.org Backpatch-through: 12
2024-08-29Disallow USING clause when altering type of generated columnPeter Eisentraut
This does not make sense. It would write the output of the USING clause into the converted column, which would violate the generation expression. This adds a check to error out if this is specified. There was a test for this, but that test errored out for a different reason, so it was not effective. Reported-by: Jian He <jian.universality@gmail.com> Reviewed-by: Yugo NAGATA <nagata@sraoss.co.jp> Discussion: https://www.postgresql.org/message-id/flat/c7083982-69f4-4b14-8315-f9ddb20b9834%40eisentraut.org
2024-08-19Avoid failure to open dropped detached partitionAlvaro Herrera
When a partition is detached and immediately dropped, a prepared statement could try to compute a new partition descriptor that includes it. This leads to this kind of error: ERROR: could not open relation with OID 457639 Avoid this by skipping the partition in expand_partitioned_rtentry if it doesn't exist. Noted by me while investigating bug #18559. Kuntal Gosh helped to identify the exact failure. Backpatch to 14, where DETACH CONCURRENTLY was introduced. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Kuntal Ghosh <kuntalghosh.2007@gmail.com> Reviewed-by: Junwang Zhao <zhjwpku@gmail.com> Discussion: https://postgr.es/m/202408122233.bo4adt3vh5bi@alvherre.pgsql
2024-08-19Explain dropdb can't use syscache because of TOASTTomas Vondra
Add a comment explaining dropdb() can't rely on syscache. The issue with flattened rows was fixed by commit 0f92b230f88b, but better to have a clear explanation why the systable scan is necessary. The other places doing in-place updates on pg_database have the same comment. Suggestion and patch by Yugo Nagata. Backpatch to 12, same as the fix. Author: Yugo Nagata Backpatch-through: 12 Discussion: https://postgr.es/m/CAJTYsWWNkCt+-UnMhg=BiCD3Mh8c2JdHLofPxsW3m2dkDFw8RA@mail.gmail.com
2024-08-19Fix regression in TLS session ticket disablingDaniel Gustafsson
Commit 274bbced disabled session tickets for TLSv1.3 on top of the already disabled TLSv1.2 session tickets, but accidentally caused a regression where TLSv1.2 session tickets were incorrectly sent. Fix by unconditionally disabling TLSv1.2 session tickets and only disable TLSv1.3 tickets when the right version of OpenSSL is used. Backpatch to all supported branches. Reported-by: Cameron Vogt <cvogt@automaticcontrols.net> Reported-by: Fire Emerald <fire.github@gmail.com> Reviewed-by: Jacob Champion <jacob.champion@enterprisedb.com> Discussion: https://postgr.es/m/DM6PR16MB3145CF62857226F350C710D1AB852@DM6PR16MB3145.namprd16.prod.outlook.com Backpatch-through: v12
2024-08-19Fix harmless LC_COLLATE[_MASK] confusion.Thomas Munro
Commit ca051d8b101 called newlocale(LC_COLLATE, ...) instead of newlocale(LC_COLLATE_MASK, ...), in code reached only on FreeBSD. They have the same value on that OS, explaining why it worked. Fix. Back-patch to 14, where ca051d8b101 landed.
2024-08-19Fix DROP DATABASE for databases with many ACLsTomas Vondra
Commit c66a7d75e652 modified DROP DATABASE so that if interrupted, the database is known to be in an invalid state and can only be dropped. This is done by setting a flag using an in-place update, so that it's not lost in case of rollback. For databases with many ACLs, this may however fail like this: ERROR: wrong tuple length This happens because with many ACLs, the pg_database.datacl attribute gets TOASTed. The dropdb() code reads the tuple from the syscache, which means it's detoasted. But the in-place update expects the tuple length to match the on-disk tuple. Fixed by reading the tuple from the catalog directly, not from syscache. Report and fix by Ayush Tiwari. Backpatch to 12. The DROP DATABASE fix was backpatched to 11, but 11 is EOL at this point. Reported-by: Ayush Tiwari Author: Ayush Tiwari Reviewed-by: Tomas Vondra Backpatch-through: 12 Discussion: https://postgr.es/m/CAJTYsWWNkCt+-UnMhg=BiCD3Mh8c2JdHLofPxsW3m2dkDFw8RA@mail.gmail.com
2024-08-12Fix creation of partition descriptor during concurrent detach+dropAlvaro Herrera
If a partition undergoes DETACH CONCURRENTLY immediately followed by DROP, this could cause a problem for a concurrent transaction recomputing the partition descriptor when running a prepared statement, because it tries to dereference a pointer to a tuple that's not found in a catalog scan. The existing retry logic added in commit dbca3469ebf8 is sufficient to cope with the overall problem, provided we don't try to dereference a non-existant heap tuple. Arguably, the code in RelationBuildPartitionDesc() has been wrong all along, since no check was added in commit 898e5e3290a7 against receiving a NULL tuple from the catalog scan; that bug has only become user-visible with DETACH CONCURRENTLY which was added in branch 14. Therefore, even though there's no known mechanism to cause a crash because of this, backpatch the addition of such a check to all supported branches. In branches prior to 14, this would cause the code to fail with a "missing relpartbound for relation XYZ" error instead of crashing; that's okay, because there are no reports of such behavior anyway. Author: Kuntal Ghosh <kuntalghosh.2007@gmail.com> Reviewed-by: Junwang Zhao <zhjwpku@gmail.com> Reviewed-by: Tender Wang <tndrwang@gmail.com> Discussion: https://postgr.es/m/18559-b48286d2eacd9a4e@postgresql.org
2024-08-11Suppress Coverity warnings about Asserts in get_name_for_var_field.Tom Lane
Coverity thinks dpns->plan could be null at these points. That shouldn't really be possible, but it's easy enough to modify the Asserts so they'd not core-dump if it were true. These are new in b919a97a6. Back-patch to v13; the v12 version of the patch didn't have these Asserts.
2024-08-10Allow adjusting session_authorization and role in parallel workers.Tom Lane
The code intends to allow GUCs to be set within parallel workers via function SET clauses, but not otherwise. However, doing so fails for "session_authorization" and "role", because the assign hooks for those attempt to set the subsidiary "is_superuser" GUC, and that call falls foul of the "not otherwise" prohibition. We can't switch to using GUC_ACTION_SAVE for this, so instead add a new GUC variable flag GUC_ALLOW_IN_PARALLEL to mark is_superuser as being safe to set anyway. (This is okay because is_superuser has context PGC_INTERNAL and thus only hard-wired calls can change it. We'd need more thought before applying the flag to other GUCs; but maybe there are other use-cases.) This isn't the prettiest fix perhaps, but other alternatives we thought of would be much more invasive. While here, correct a thinko in commit 059de3ca4: when rejecting a GUC setting within a parallel worker, we should return 0 not -1 if the ereport doesn't longjmp. (This seems to have no consequences right now because no caller cares, but it's inconsistent.) Improve the comments to try to forestall future confusion of the same kind. Despite the lack of field complaints, this seems worth back-patching. Thanks to Nathan Bossart for the idea to invent a new flag, and for review. Discussion: https://postgr.es/m/2833457.1723229039@sss.pgh.pa.us
2024-08-09Fix "failed to find plan for subquery/CTE" errors in EXPLAIN.Tom Lane
To deparse a reference to a field of a RECORD-type output of a subquery, EXPLAIN normally digs down into the subquery's plan to try to discover exactly which anonymous RECORD type is meant. However, this can fail if the subquery has been optimized out of the plan altogether on the grounds that no rows could pass the WHERE quals, which has been possible at least since 3fc6e2d7f. There isn't anything remaining in the plan tree that would help us, so fall back to printing the field name as "fN" for the N'th column of the record. (This will actually be the right thing some of the time, since it matches the column names we assign to RowExprs.) In passing, fix a comment typo in create_projection_plan, which I noticed while experimenting with an alternative fix for this. Per bug #18576 from Vasya B. Back-patch to all supported branches. Richard Guo and Tom Lane Discussion: https://postgr.es/m/18576-9feac34e132fea9e@postgresql.org
2024-08-08Refuse ATTACH of a table referenced by a foreign keyAlvaro Herrera
Trying to attach a table as a partition which is already on the referenced side of a foreign key on the partitioned table that it is being attached to, leads to strange behavior: we try to clone the foreign key from the parent to the partition, but this new FK points to the partition itself, and the mix of pg_constraint rows and triggers doesn't behave well. Rather than trying to untangle the mess (which might be possible given sufficient time), I opted to forbid the ATTACH. This doesn't seem a problematic restriction, given that we already fail to create the foreign key if you do it the other way around, that is, having the partition first and the FK second. Backpatch to all supported branches. Reported-by: Alexander Lakhin <exclusion@gmail.com> Reviewed-by: Tender Wang <tndrwang@gmail.com> Discussion: https://postgr.es/m/18541-628a61bc267cd2d3@postgresql.org