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2023-01-20Make our back branches build under -fkeep-inline-functions.Tom Lane
Add "#ifndef FRONTEND" where necessary to make pg_waldump build on compilers that don't elide unused static-inline functions. This back-patches relevant parts of commit 3e9ca5260, fixing build breakage from dc7420c2c and back-patching of f10f0ae42. Per recently-resurrected buildfarm member castoroides. We aren't expecting castoroides to build anything newer than v11, but we might as well clean up the intermediate branches while at it.
2023-01-15Make new GENERATED-expressions code more bulletproof.Tom Lane
In commit 8bf6ec3ba I assumed that no code path could reach ExecGetExtraUpdatedCols without having gone through ExecInitStoredGenerated. That turns out not to be the case in logical replication: if there's an ON UPDATE trigger on the target table, trigger.c will call this code before anybody has set up its generated columns. Having seen that, I don't have a lot of faith in there not being other such paths. ExecGetExtraUpdatedCols can call ExecInitStoredGenerated for itself, as long as we are willing to assume that it is only called in CMD_UPDATE operations, which on the whole seems like a safer leap of faith. Per report from Vitaly Davydov. Discussion: https://postgr.es/m/d259d69652b8c2ff50e14cda3c236c7f@postgrespro.ru
2023-01-05Fix calculation of which GENERATED columns need to be updated.Tom Lane
We were identifying the updatable generated columns of inheritance children by transposing the calculation made for their parent. However, there's nothing that says a traditional-inheritance child can't have generated columns that aren't there in its parent, or that have different dependencies than are in the parent's expression. (At present it seems that we don't enforce that for partitioning either, which is likely wrong to some degree or other; but the case clearly needs to be handled with traditional inheritance.) Hence, drop the very-klugy-anyway "extraUpdatedCols" RTE field in favor of identifying which generated columns depend on updated columns during executor startup. In HEAD we can remove extraUpdatedCols altogether; in back branches, it's still there but always empty. Another difference between the HEAD and back-branch versions of this patch is that in HEAD we can add the new bitmap field to ResultRelInfo, but that would cause an ABI break in back branches. Like 4b3e37993, add a List field at the end of struct EState instead. Back-patch to v13. The bogus calculation is also being made in v12, but it doesn't have the same visible effect because we don't use it to decide which generated columns to recalculate; as a consequence of which the patch doesn't apply easily. I think that there might still be a demonstrable bug associated with trigger firing conditions, but that's such a weird corner-case usage that I'm content to leave it unfixed in v12. Amit Langote and Tom Lane Discussion: https://postgr.es/m/CA+HiwqFshLKNvQUd1DgwJ-7tsTp=dwv7KZqXC4j2wYBV1aCDUA@mail.gmail.com Discussion: https://postgr.es/m/2793383.1672944799@sss.pgh.pa.us
2023-01-02perl: Hide warnings inside perl.h when using gcc compatible compilerAndres Freund
New versions of perl trigger warnings within perl.h with our compiler flags. At least -Wdeclaration-after-statement, -Wshadow=compatible-local are known to be problematic. To avoid these warnings, conditionally use #pragma GCC system_header before including plperl.h. Alternatively, we could add the include paths for problematic headers with -isystem, but that is a larger hammer and is harder to search for. A more granular alternative would be to use #pragma GCC diagnostic push/ignored/pop, but gcc warns about unknown warnings being ignored, so every to-be-ignored-temporarily compiler warning would require its own pg_config.h symbol and #ifdef. As the warnings are voluminous, it makes sense to backpatch this change. But don't do so yet, we first want gather buildfarm coverage - it's e.g. possible that some compiler claiming to be gcc compatible has issues with the pragma. Author: Andres Freund <andres@anarazel.de> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: Discussion: https://postgr.es/m/20221228182455.hfdwd22zztvkojy2@awork3.anarazel.de
2022-12-13Rethink handling of [Prevent|Is]InTransactionBlock in pipeline mode.Tom Lane
Commits f92944137 et al. made IsInTransactionBlock() set the XACT_FLAGS_NEEDIMMEDIATECOMMIT flag before returning "false", on the grounds that that kept its API promises equivalent to those of PreventInTransactionBlock(). This turns out to be a bad idea though, because it allows an ANALYZE in a pipelined series of commands to cause an immediate commit, which is unexpected. Furthermore, if we return "false" then we have another issue, which is that ANALYZE will decide it's allowed to do internal commit-and-start-transaction sequences, thus possibly unexpectedly committing the effects of previous commands in the pipeline. To fix the latter situation, invent another transaction state flag XACT_FLAGS_PIPELINING, which explicitly records the fact that we have executed some extended-protocol command and not yet seen a commit for it. Then, require that flag to not be set before allowing InTransactionBlock() to return "false". Having done that, we can remove its setting of NEEDIMMEDIATECOMMIT without fear of causing problems. This means that the API guarantees of IsInTransactionBlock now diverge from PreventInTransactionBlock, which is mildly annoying, but it seems OK given the very limited usage of IsInTransactionBlock. (In any case, a caller preferring the old behavior could always set NEEDIMMEDIATECOMMIT for itself.) For consistency also require XACT_FLAGS_PIPELINING to not be set in PreventInTransactionBlock. This too is meant to prevent commands such as CREATE DATABASE from silently committing previous commands in a pipeline. Per report from Peter Eisentraut. As before, back-patch to all supported branches (which sadly no longer includes v10). Discussion: https://postgr.es/m/65a899dd-aebc-f667-1d0a-abb89ff3abf8@enterprisedb.com
2022-11-29Improve heuristics for compressing the KnownAssignedXids array.Tom Lane
Previously, we'd compress only when the active range of array entries reached Max(4 * PROCARRAY_MAXPROCS, 2 * pArray->numKnownAssignedXids). If max_connections is large, the first term could result in not compressing for a long time, resulting in much wastage of cycles in hot-standby backends scanning the array to take snapshots. Get rid of that term, and just bound it to 2 * pArray->numKnownAssignedXids. That however creates the opposite risk, that we might spend too much effort compressing. Hence, consider compressing only once every 128 commit records. (This frequency was chosen by benchmarking. While we only tried one benchmark scenario, the results seem stable over a fairly wide range of frequencies.) Also, force compression when processing RecoveryInfo WAL records (which should be infrequent); the old code could perform compression then, but would do so only after the same array-range check as for the transaction-commit path. Also, opportunistically run compression if the startup process is about to wait for WAL, though not oftener than once a second. This should prevent cases where we waste lots of time by leaving the array not-compressed for long intervals due to low WAL traffic. Lastly, add a simple check to keep us from uselessly compressing when the array storage is already compact. Back-patch, as the performance problem is worse in pre-v14 branches than in HEAD. Simon Riggs and Michail Nikolaev, with help from Tom Lane and Andres Freund. Discussion: https://postgr.es/m/CALdSSPgahNUD_=pB_j=1zSnDBaiOtqVfzo8Ejt5J_k7qZiU1Tw@mail.gmail.com
2022-11-21Add comments and a missing CHECK_FOR_INTERRUPTS in ts_headline.Tom Lane
I just spent an annoying amount of time reverse-engineering the 100%-undocumented API between ts_headline and the text search parser's prsheadline function. Add some commentary about that while it's fresh in mind. Also remove some unused macros in wparser_def.c. While at it, I noticed that when commit 78e73e875 added a CHECK_FOR_INTERRUPTS call in TS_execute_recurse, it missed doing so in the parallel function TS_phrase_execute, which surely needs one just as much. Back-patch because of the missing CHECK_FOR_INTERRUPTS. Might as well back-patch the rest of this too.
2022-11-17Replace RelationOpenSmgr() with RelationGetSmgr().Tom Lane
This is a back-patch of the v15-era commit f10f0ae42 into older supported branches. The idea is to design out bugs in which an ill-timed relcache flush clears rel->rd_smgr partway through some code sequence that wasn't expecting that. We had another report today of a corner case that reliably crashes v14 under debug_discard_caches (nee CLOBBER_CACHE_ALWAYS), and therefore would crash once in a blue moon in the field. We're unlikely to get rid of all such code paths unless we adopt the more rigorous coding rules instituted by f10f0ae42. Therefore, even though this is a bit invasive, it's time to back-patch. Some comfort can be taken in the fact that f10f0ae42 has been in v15 for 16 months without problems. I left the RelationOpenSmgr macro present in the back branches, even though no core code should use it anymore, in order to not break third-party extensions in minor releases. Such extensions might opt to start using RelationGetSmgr instead, to reduce their code differential between v15 and earlier branches. This carries a hazard of failing to compile against headers from existing minor releases. However, once compiled the extension should work fine even with such releases, because RelationGetSmgr is a "static inline" function so it creates no link-time dependency. So depending on distribution practices, that might be an OK tradeoff. Per report from Spyridon Dimitrios Agathos. Original patch by Amul Sul. Discussion: https://postgr.es/m/CAFM5RaqdgyusQvmWkyPYaWMwoK5gigdtW-7HcgHgOeAw7mqJ_Q@mail.gmail.com Discussion: https://postgr.es/m/CANiYTQsU7yMFpQYnv=BrcRVqK_3U3mtAzAsJCaqtzsDHfsUbdQ@mail.gmail.com
2022-11-03Add casts to simplehash.h to silence C++ warnings.Tom Lane
Casting the result of palloc etc. to the intended type is more per project style anyway. (The fact that cpluspluscheck doesn't notice these problems is because it doesn't expand any macros, which seems like a troubling shortcoming. Don't have a good idea about improving that.) Back-patch to v13, which is as far as the patch applies cleanly; doesn't seem worth working harder. David Geier Discussion: https://postgr.es/m/aa5d88a3-71f4-3455-11cf-82de0372c941@gmail.com
2022-11-02Allow use of __sync_lock_test_and_set for spinlocks on any machine.Tom Lane
If we have no special-case code in s_lock.h for the current platform, but the compiler has __sync_lock_test_and_set, use that instead of failing. It's unlikely that anybody's __sync_lock_test_and_set would be so awful as to be worse than our semaphore-based fallback, but if it is, they can (continue to) use --disable-spinlocks. This allows removal of the RISC-V special case installed by commit c32fcac56, which generated exactly the same code but only on that platform. Usefully, the RISC-V buildfarm animals should now test at least the int variant of this patch. I've manually tested both variants on ARM by dint of removing the ARM-specific stanza. We don't want to drop that, because it already has some special knowledge and is likely to grow more over time. Likewise, this is not meant to preclude installing special cases for other arches if that proves worthwhile. Per discussion of a request to install the same code for loongarch64. Like the previous patch, we might as well back-patch to supported branches. Discussion: https://postgr.es/m/761ac43d44b84d679ba803c2bd947cc0@HSMAILSVR04.hs.handsome.com.cn
2022-10-21pg_basebackup: Fix cross-platform tablespace relocation.Robert Haas
Specifically, when pg_basebackup is invoked with -Tx=y, don't error out if x could plausibly be an absolute path either on Windows or on non-Windows systems. We don't know whether the remote system is running the same OS as the local system, so it's not appropriate to assume that our local rule about absolute pathnames is the same as the rule on the remote system. Patch by me, reviewed by Tom Lane, Andrew Dunstan, and Davinder Singh. Discussion: http://postgr.es/m/CA+TgmoY+jC3YiskomvYKDPK3FbrmsDU7_8+wMHt02HOdJeRb0g@mail.gmail.com
2022-10-16Rename parser token REF to REF_P to avoid a symbol conflict.Tom Lane
In the latest version of Apple's macOS SDK, <sys/socket.h> fails to compile if "REF" is #define'd as something. Apple may or may not agree that this is a bug, and even if they do accept the bug report I filed, they probably won't fix it very quickly. In the meantime, our back branches will all fail to compile gram.y. v15 and HEAD currently escape the problem thanks to the refactoring done in 98e93a1fc, but that's purely accidental. Moreover, since that patch removed a widely-visible inclusion of <netdb.h>, back-patching it seems too likely to break third-party code. Instead, change the token's code name to REF_P, following our usual convention for naming parser tokens that are likely to have symbol conflicts. The effects of that should be localized to the grammar and immediately surrounding files, so it seems like a safer answer. Per project policy that we want to keep recently-out-of-support branches buildable on modern systems, back-patch all the way to 9.2. Discussion: https://postgr.es/m/1803927.1665938411@sss.pgh.pa.us
2022-09-17Make check_usermap() parameter names consistent.Peter Geoghegan
The function has a bool argument named "case_insensitive", but that was spelled "case_sensitive" in the declaration. Make them consistent now to avoid confusion in the future. Author: Peter Geoghegan <pg@bowt.ie> Reviewed-By: Michael Paquiër <michael@paquier.xyz> Discussion: https://postgr.es/m/CAH2-WznJt9CMM9KJTMjJh_zbL5hD9oX44qdJ4aqZtjFi-zA3Tg@mail.gmail.com Backpatch: 10-
2022-09-14Expand palloc/pg_malloc API for more type safetyPeter Eisentraut
This adds additional variants of palloc, pg_malloc, etc. that encapsulate common usage patterns and provide more type safety. Specifically, this adds palloc_object(), palloc_array(), and repalloc_array(), which take the type name of the object to be allocated as its first argument and cast the return as a pointer to that type. There are also palloc0_object() and palloc0_array() variants for initializing with zero, and pg_malloc_*() variants of all of the above. Inspired by the talloc library. This is backpatched from master so that future backpatchable code can make use of these APIs. This patch by itself does not contain any users of these APIs. Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://www.postgresql.org/message-id/flat/bb755632-2a43-d523-36f8-a1e7a389a907@enterprisedb.com
2022-09-06Further fixes for MULTIEXPR_SUBLINK fix.Tom Lane
Some more things I didn't think about in commits 3f7323cbb et al: MULTIEXPR_SUBLINK subplans might have been converted to initplans instead of regular subplans, in which case they won't show up in the modified targetlist. Fortunately, this would only happen if they have no input parameters, which means that the problem we originally needed to fix can't happen with them. Therefore, there's no need to clone their output parameters, and thus it doesn't hurt that we'll fail to see them in the first pass over the targetlist. Nonetheless, this complicates matters greatly, because now we have to distinguish output Params of initplans (which shouldn't get renumbered) from those of regular subplans (which should). This also breaks the simplistic scheme I used of assuming that the subplans found in the targetlist have consecutive subLinkIds. We really can't avoid the need to know the subplans' subLinkIds in this code. To fix that, add subLinkId as the last field of SubPlan. We can get away with that change in back branches because SubPlan nodes will never be stored in the catalogs, and there's no ABI break for external code that might be looking at the existing fields of SubPlan. Secondly, rewriteTargetListIU might have rolled up multiple FieldStores or SubscriptingRefs into one targetlist entry, breaking the assumption that there's at most one Param to fix per targetlist entry. (That assumption is OK I think in the ruleutils.c code I stole the logic from in 18f51083c, because that only deals with pre-rewrite query trees. But it's definitely not OK here.) Abandon that shortcut and just do a full tree walk on the targetlist to ensure we find all the Params we have to change. Per bug #17606 from Andre Lin. As before, only v10-v13 need the patch. Discussion: https://postgr.es/m/17606-e5c8ad18d31db96a@postgresql.org
2022-08-27Repair rare failure of MULTIEXPR_SUBLINK subplans in inherited updates.Tom Lane
Prior to v14, if we have a MULTIEXPR SubPlan (that is, use of the syntax UPDATE ... SET (c1, ...) = (SELECT ...)) in an UPDATE with an inherited or partitioned target table, inheritance_planner() will clone the targetlist and therefore also the MULTIEXPR SubPlan and the Param nodes referencing it for each child target table. Up to now, we've allowed all the clones to share the underlying subplan as well as the output parameter IDs -- that is, the runtime ParamExecData slots. That technique is borrowed from the far older code that supports initplans, and it works okay in that case because the cloned SubPlan nodes are essentially identical. So it doesn't matter which one of the clones the shared ParamExecData.execPlan field might point to. However, this fails to hold for MULTIEXPR SubPlans, because they can have nonempty "args" lists (values to be passed into the subplan), and those lists could get mutated to different states in the various clones. In the submitted reproducer, as well as the test case added here, one clone contains Vars with varno OUTER_VAR where another has INNER_VAR, because the child tables are respectively on the outer or inner side of the join. Sharing the execPlan pointer can result in trying to evaluate an args list that doesn't match the local execution state, with mayhem ensuing. The result often is to trigger consistency checks in the executor, but I believe this could end in a crash or incorrect updates. To fix, assign new Param IDs to each of the cloned SubPlans, so that they don't share ParamExecData slots at runtime. It still seems fine for the clones to share the underlying subplan, and extra ParamExecData slots are cheap enough that this fix shouldn't cost much. This has been busted since we invented MULTIEXPR SubPlans in 9.5. Probably the lack of previous reports is because query plans in which the different clones of a MULTIEXPR mutate to effectively-different states are pretty rare. There's no issue in v14 and later, because without inheritance_planner() there's never a reason to clone MULTIEXPR SubPlans. Per bug #17596 from Andre Lin. Patch v10-v13 only. Discussion: https://postgr.es/m/17596-c5357f61427a81dc@postgresql.org
2022-08-11Fix catalog lookup with the wrong snapshot during logical decoding.Amit Kapila
Previously, we relied on HEAP2_NEW_CID records and XACT_INVALIDATION records to know if the transaction has modified the catalog, and that information is not serialized to snapshot. Therefore, after the restart, if the logical decoding decodes only the commit record of the transaction that has actually modified a catalog, we will miss adding its XID to the snapshot. Thus, we will end up looking at catalogs with the wrong snapshot. To fix this problem, this changes the snapshot builder so that it remembers the last-running-xacts list of the decoded RUNNING_XACTS record after restoring the previously serialized snapshot. Then, we mark the transaction as containing catalog changes if it's in the list of initial running transactions and its commit record has XACT_XINFO_HAS_INVALS. To avoid ABI breakage, we store the array of the initial running transactions in the static variables InitialRunningXacts and NInitialRunningXacts, instead of storing those in SnapBuild or ReorderBuffer. This approach has a false positive; we could end up adding the transaction that didn't change catalog to the snapshot since we cannot distinguish whether the transaction has catalog changes only by checking the COMMIT record. It doesn't have the information on which (sub) transaction has catalog changes, and XACT_XINFO_HAS_INVALS doesn't necessarily indicate that the transaction has catalog change. But that won't be a problem since we use snapshot built during decoding only to read system catalogs. On the master branch, we took a more future-proof approach by writing catalog modifying transactions to the serialized snapshot which avoids the above false positive. But we cannot backpatch it because of a change in the SnapBuild. Reported-by: Mike Oh Author: Masahiko Sawada Reviewed-by: Amit Kapila, Shi yu, Takamichi Osumi, Kyotaro Horiguchi, Bertrand Drouvot, Ahsan Hadi Backpatch-through: 10 Discussion: https://postgr.es/m/81D0D8B0-E7C4-4999-B616-1E5004DBDCD2%40amazon.com
2022-08-08In extensions, don't replace objects not belonging to the extension.Tom Lane
Previously, if an extension script did CREATE OR REPLACE and there was an existing object not belonging to the extension, it would overwrite the object and adopt it into the extension. This is problematic, first because the overwrite is probably unintentional, and second because we didn't change the object's ownership. Thus a hostile user could create an object in advance of an expected CREATE EXTENSION command, and would then have ownership rights on an extension object, which could be modified for trojan-horse-type attacks. Hence, forbid CREATE OR REPLACE of an existing object unless it already belongs to the extension. (Note that we've always forbidden replacing an object that belongs to some other extension; only the behavior for previously-free-standing objects changes here.) For the same reason, also fail CREATE IF NOT EXISTS when there is an existing object that doesn't belong to the extension. Our thanks to Sven Klemm for reporting this problem. Security: CVE-2022-2625
2022-08-05Fix ENABLE/DISABLE TRIGGER to handle recursion correctlyAlvaro Herrera
Using ATSimpleRecursion() in ATPrepCmd() to do so as bbb927b4db9b did is not correct, because ATPrepCmd() can't distinguish between triggers that may be cloned and those that may not, so would wrongly try to recurse for the latter category of triggers. So this commit restores the code in EnableDisableTrigger() that 86f575948c77 had added to do the recursion, which would do it only for triggers that may be cloned, that is, row-level triggers. This also changes tablecmds.c such that ATExecCmd() is able to pass the value of ONLY flag down to EnableDisableTrigger() using its new 'recurse' parameter. This also fixes what seems like an oversight of 86f575948c77 that the recursion to partition triggers would only occur if EnableDisableTrigger() had actually changed the trigger. It is more apt to recurse to inspect partition triggers even if the parent's trigger didn't need to be changed: only then can we be certain that all descendants share the same state afterwards. Backpatch all the way back to 11, like bbb927b4db9b. Care is taken not to break ABI compatibility (and that no catversion bump is needed.) Co-authored-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Dmitry Koval <d.koval@postgrespro.ru> Discussion: https://postgr.es/m/CA+HiwqG-cZT3XzGAnEgZQLoQbyfJApVwOTQaCaas1mhpf+4V5A@mail.gmail.com
2022-08-03Fix incorrect tests for SRFs in relation_can_be_sorted_early().Tom Lane
Commit fac1b470a thought we could check for set-returning functions by testing only the top-level node in an expression tree. This is wrong in itself, and to make matters worse it encouraged others to make the same mistake, by exporting tlist.c's special-purpose IS_SRF_CALL() as a widely-visible macro. I can't find any evidence that anyone's taken the bait, but it was only a matter of time. Use expression_returns_set() instead, and stuff the IS_SRF_CALL() genie back in its bottle, this time with a warning label. I also added a couple of cross-reference comments. After a fair amount of fooling around, I've despaired of making a robust test case that exposes the bug reliably, so no test case here. (Note that the test case added by fac1b470a is itself broken, in that it doesn't notice if you remove the code change. The repro given by the bug submitter currently doesn't fail either in v15 or HEAD, though I suspect that may indicate an unrelated bug.) Per bug #17564 from Martijn van Oosterhout. Back-patch to v13, as the faulty patch was. Discussion: https://postgr.es/m/17564-c7472c2f90ef2da3@postgresql.org
2022-07-27Allow "in place" tablespaces.Alvaro Herrera
This is a backpatch to branches 10-14 of the following commits: 7170f2159fb2 Allow "in place" tablespaces. c6f2f01611d4 Fix pg_basebackup with in-place tablespaces. f6f0db4d6240 Fix pg_tablespace_location() with in-place tablespaces 7a7cd84893e0 doc: Remove mention to in-place tablespaces for pg_tablespace_location() 5344723755bd Remove unnecessary Windows-specific basebackup code. In-place tablespaces were introduced as a testing helper mechanism, but they are going to be used for a bugfix in WAL replay to be backpatched to all stable branches. I (Álvaro) had to adjust some code to account for lack of get_dirent_type() in branches prior to 14. Author: Thomas Munro <thomas.munro@gmail.com> Author: Michaël Paquier <michael@paquier.xyz> Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Discussion: https://postgr.es/m/20220722081858.omhn2in5zt3g4nek@alvherre.pgsql
2022-07-26Force immediate commit after CREATE DATABASE etc in extended protocol.Tom Lane
We have a few commands that "can't run in a transaction block", meaning that if they complete their processing but then we fail to COMMIT, we'll be left with inconsistent on-disk state. However, the existing defenses for this are only watertight for simple query protocol. In extended protocol, we didn't commit until receiving a Sync message. Since the client is allowed to issue another command instead of Sync, we're in trouble if that command fails or is an explicit ROLLBACK. In any case, sitting in an inconsistent state while waiting for a client message that might not come seems pretty risky. This case wasn't reachable via libpq before we introduced pipeline mode, but it's always been an intended aspect of extended query protocol, and likely there are other clients that could reach it before. To fix, set a flag in PreventInTransactionBlock that tells exec_execute_message to force an immediate commit. This seems to be the approach that does least damage to existing working cases while still preventing the undesirable outcomes. While here, add some documentation to protocol.sgml that explicitly says how to use pipelining. That's latent in the existing docs if you know what to look for, but it's better to spell it out; and it provides a place to document this new behavior. Per bug #17434 from Yugo Nagata. It's been wrong for ages, so back-patch to all supported branches. Discussion: https://postgr.es/m/17434-d9f7a064ce2a88a3@postgresql.org
2022-07-18Re-add SPICleanup for ABI compatibility in stable branchPeter Eisentraut
This fixes an ABI break introduced by cfc86f987349372dbbfc0391f9f519c0a7b27b84. Author: Markus Wanner <markus.wanner@enterprisedb.com> Discussion: https://www.postgresql.org/message-id/defd749a-8410-841d-1126-21398686d63d@enterprisedb.com
2022-07-11Fix lock assertions in dshash.c.Thomas Munro
dshash.c previously maintained flags to be able to assert that you didn't hold any partition lock. These flags could get out of sync with reality in error scenarios. Get rid of all that, and make assertions about the locks themselves instead. Since LWLockHeldByMe() loops internally, we don't want to put that inside another loop over all partition locks. Introduce a new debugging-only interface LWLockAnyHeldByMe() to avoid that. This problem was noted by Tom and Andres while reviewing changes to support the new shared memory stats system, and later showed up in reality while working on commit 389869af. Back-patch to 11, where dshash.c arrived. Reported-by: Tom Lane <tgl@sss.pgh.pa.us> Reported-by: Andres Freund <andres@anarazel.de> Reviewed-by: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp> Reviewed-by: Zhihong Yu <zyu@yugabyte.com> Reviewed-by: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/20220311012712.botrpsikaufzteyt@alap3.anarazel.de Discussion: https://postgr.es/m/CA%2BhUKGJ31Wce6HJ7xnVTKWjFUWQZPBngxfJVx4q0E98pDr3kAw%40mail.gmail.com
2022-06-22Fix SPI's handling of errors during transaction commit.Tom Lane
SPI_commit previously left it up to the caller to recover from any error occurring during commit. Since that's complicated and requires use of low-level xact.c facilities, it's not too surprising that no caller got it right. Let's move the responsibility for cleanup into spi.c. Doing that requires redefining SPI_commit as starting a new transaction, so that it becomes equivalent to SPI_commit_and_chain except that you get default transaction characteristics instead of preserving the prior transaction's characteristics. We can make this pretty transparent API-wise by redefining SPI_start_transaction() as a no-op. Callers that expect to do something in between might be surprised, but available evidence is that no callers do so. Having made that API redefinition, we can fix this mess by having SPI_commit[_and_chain] trap errors and start a new, clean transaction before re-throwing the error. Likewise for SPI_rollback[_and_chain]. Some cleanup is also needed in AtEOXact_SPI, which was nowhere near smart enough to deal with SPI contexts nested inside a committing context. While plperl and pltcl need no changes beyond removing their now-useless SPI_start_transaction() calls, plpython needs some more work because it hadn't gotten the memo about catching commit/rollback errors in the first place. Such an error resulted in longjmp'ing out of the Python interpreter, which leaks Python stack entries at present and is reported to crash Python 3.11 altogether. Add the missing logic to catch such errors and convert them into Python exceptions. This is a back-patch of commit 2e517818f. That's now aged long enough to reduce the concerns about whether it will break something, and we do need to ensure that supported branches will work with Python 3.11. Peter Eisentraut and Tom Lane Discussion: https://postgr.es/m/3375ffd8-d71c-2565-e348-a597d6e739e3@enterprisedb.com Discussion: https://postgr.es/m/17416-ed8fe5d7213d6c25@postgresql.org
2022-06-16Fix data inconsistency between publisher and subscriber.Amit Kapila
We were not updating the partition map cache in the subscriber even when the corresponding remote rel is changed. Due to this data was getting incorrectly replicated for partition tables after the publisher has changed the table schema. Fix it by resetting the required entries in the partition map cache after receiving a new relation mapping from the publisher. Reported-by: Shi Yu Author: Shi Yu, Hou Zhijie Reviewed-by: Amit Langote, Amit Kapila Backpatch-through: 13, where it was introduced Discussion: https://postgr.es/m/OSZPR01MB6310F46CD425A967E4AEF736FDA49@OSZPR01MB6310.jpnprd01.prod.outlook.com
2022-05-19Repurpose PROC_COPYABLE_FLAGS as PROC_XMIN_FLAGSAlvaro Herrera
This is a slight, convenient semantics change from what commit 0f0cfb494004 ("Fix parallel operations that prevent oldest xmin from advancing") introduced that lets us simplify the coding in the one place where it is used. Backpatch to 13. This is related to commit 6fea65508a1a ("Tighten ComputeXidHorizons' handling of walsenders") rewriting the code site where this is used, which has not yet been backpatched, but it may well be in the future. Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com> Discussion: https://postgr.es/m/202204191637.eldwa2exvguw@alvherre.pgsql
2022-05-11Fix the logical replication timeout during large transactions.Amit Kapila
The problem is that we don't send keep-alive messages for a long time while processing large transactions during logical replication where we don't send any data of such transactions. This can happen when the table modified in the transaction is not published or because all the changes got filtered. We do try to send the keep_alive if necessary at the end of the transaction (via WalSndWriteData()) but by that time the subscriber-side can timeout and exit. To fix this we try to send the keepalive message if required after processing certain threshold of changes. Reported-by: Fabrice Chapuis Author: Wang wei and Amit Kapila Reviewed By: Masahiko Sawada, Euler Taveira, Hou Zhijie, Hayato Kuroda Backpatch-through: 10 Discussion: https://postgr.es/m/CAA5-nLARN7-3SLU_QUxfy510pmrYK6JJb=bk3hcgemAM_pAv+w@mail.gmail.com
2022-04-21Remove inadequate assertion check in CTE inlining.Tom Lane
inline_cte() expected to find exactly as many references to the target CTE as its cterefcount indicates. While that should be accurate for the tree as emitted by the parser, there are some optimizations that occur upstream of here that could falsify it, notably removal of unused subquery output expressions. Trying to make the accounting 100% accurate seems expensive and doomed to future breakage. It's not really worth it, because all this code is protecting is downstream assumptions that every referenced CTE has a plan. Let's convert those assertions to regular test-and-elog just in case there's some actual problem, and then drop the failing assertion. Per report from Tomas Vondra (thanks also to Richard Guo for analysis). Back-patch to v12 where the faulty code came in. Discussion: https://postgr.es/m/29196a1e-ed47-c7ca-9be2-b1c636816183@enterprisedb.com
2022-04-14Rethink the delay-checkpoint-end mechanism in the back-branches.Robert Haas
The back-patch of commit bbace5697df12398e87ffd9879171c39d27f5b33 had the unfortunate effect of changing the layout of PGPROC in the back-branches, which could break extensions. This happened because it changed the delayChkpt from type bool to type int. So, change it back, and add a new bool delayChkptEnd field instead. The new field should fall within what used to be padding space within the struct, and so hopefully won't cause any extensions to break. Per report from Markus Wanner and discussion with Tom Lane and others. Patch originally by me, somewhat revised by Markus Wanner per a suggestion from Michael Paquier. A very similar patch was developed by Kyotaro Horiguchi, but I failed to see the email in which that was posted before writing one of my own. Discussion: http://postgr.es/m/CA+Tgmoao-kUD9c5nG5sub3F7tbo39+cdr8jKaOVEs_1aBWcJ3Q@mail.gmail.com Discussion: http://postgr.es/m/20220406.164521.17171257901083417.horikyota.ntt@gmail.com
2022-04-13Prevent access to no-longer-pinned buffer in heapam_tuple_lock().Tom Lane
heap_fetch() used to have a "keep_buf" parameter that told it to return ownership of the buffer pin to the caller after finding that the requested tuple TID exists but is invisible to the specified snapshot. This was thoughtlessly removed in commit 5db6df0c0, which broke heapam_tuple_lock() (formerly EvalPlanQualFetch) because that function needs to do more accesses to the tuple even if it's invisible. The net effect is that we would continue to touch the page for a microsecond or two after releasing pin on the buffer. Usually no harm would result; but if a different session decided to defragment the page concurrently, we could see garbage data and mistakenly conclude that there's no newer tuple version to chain up to. (It's hard to say whether this has happened in the field. The bug was actually found thanks to a later change that allowed valgrind to detect accesses to non-pinned buffers.) The most reasonable way to fix this is to reintroduce keep_buf, although I made it behave slightly differently: buffer ownership is passed back only if there is a valid tuple at the requested TID. In HEAD, we can just add the parameter back to heap_fetch(). To avoid an API break in the back branches, introduce an additional function heap_fetch_extended() in those branches. In HEAD there is an additional, less obvious API change: tuple->t_data will be set to NULL in all cases where buffer ownership is not returned, in particular when the tuple exists but fails the time qual (and !keep_buf). This is to defend against any other callers attempting to access non-pinned buffers. We concluded that making that change in back branches would be more likely to introduce problems than cure any. In passing, remove a comment about heap_fetch that was obsoleted by 9a8ee1dc6. Per bug #17462 from Daniil Anisimov. Back-patch to v12 where the bug was introduced. Discussion: https://postgr.es/m/17462-9c98a0f00df9bd36@postgresql.org
2022-04-02Remove obsolete commentPeter Eisentraut
accidentally left behind by 4cb658af70027c3544fb843d77b2e84028762747
2022-03-29Revert "Fix replay of create database records on standby"Alvaro Herrera
This reverts commit 49d9cfc68bf4. The approach taken by this patch has problems, so we'll come up with a radically different fix. Discussion: https://postgr.es/m/CA+TgmoYcUPL+WOJL2ZzhH=zmrhj0iOQ=iCFM0SuYqBbqZEamEg@mail.gmail.com
2022-03-26Suppress compiler warning in relptr_store().Tom Lane
clang 13 with -Wextra warns that "performing pointer subtraction with a null pointer has undefined behavior" in the places where freepage.c tries to set a relptr variable to constant NULL. This appears to be a compiler bug, but it's unlikely to get fixed instantly. Fortunately, we can work around it by introducing an inline support function, which seems like a good change anyway because it removes the macro's existing double-evaluation hazard. Backpatch to v10 where this code was introduced. Patch by me, based on an idea of Andres Freund's. Discussion: https://postgr.es/m/48826.1648310694@sss.pgh.pa.us
2022-03-25Fix replay of create database records on standbyAlvaro Herrera
Crash recovery on standby may encounter missing directories when replaying create database WAL records. Prior to this patch, the standby would fail to recover in such a case. However, the directories could be legitimately missing. Consider a sequence of WAL records as follows: CREATE DATABASE DROP DATABASE DROP TABLESPACE If, after replaying the last WAL record and removing the tablespace directory, the standby crashes and has to replay the create database record again, the crash recovery must be able to move on. This patch adds a mechanism similar to invalid-page tracking, to keep a tally of missing directories during crash recovery. If all the missing directory references are matched with corresponding drop records at the end of crash recovery, the standby can safely continue following the primary. Backpatch to 13, at least for now. The bug is older, but fixing it in older branches requires more careful study of the interactions with commit e6d8069522c8, which appeared in 13. A new TAP test file is added to verify the condition. However, because it depends on commit d6d317dbf615, it can only be added to branch master. I (Álvaro) manually verified that the code behaves as expected in branch 14. It's a bit nervous-making to leave the code uncovered by tests in older branches, but leaving the bug unfixed is even worse. Also, the main reason this fix took so long is precisely that we couldn't agree on a good strategy to approach testing for the bug, so perhaps this is the best we can do. Diagnosed-by: Paul Guo <paulguo@gmail.com> Author: Paul Guo <paulguo@gmail.com> Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Author: Asim R Praveen <apraveen@pivotal.io> Discussion: https://postgr.es/m/CAEET0ZGx9AvioViLf7nbR_8tH9-=27DN5xWJ2P9-ROH16e4JUA@mail.gmail.com
2022-03-24Fix possible recovery trouble if TRUNCATE overlaps a checkpoint.Robert Haas
If TRUNCATE causes some buffers to be invalidated and thus the checkpoint does not flush them, TRUNCATE must also ensure that the corresponding files are truncated on disk. Otherwise, a replay from the checkpoint might find that the buffers exist but have the wrong contents, which may cause replay to fail. Report by Teja Mupparti. Patch by Kyotaro Horiguchi, per a design suggestion from Heikki Linnakangas, with some changes to the comments by me. Review of this and a prior patch that approached the issue differently by Heikki Linnakangas, Andres Freund, Álvaro Herrera, Masahiko Sawada, and Tom Lane. Discussion: http://postgr.es/m/BYAPR06MB6373BF50B469CA393C614257ABF00@BYAPR06MB6373.namprd06.prod.outlook.com
2022-03-16Fix waiting in RegisterSyncRequest().Thomas Munro
If we run out of space in the checkpointer sync request queue (which is hopefully rare on real systems, but common with very small buffer pool), we wait for it to drain. While waiting, we should report that as a wait event so that users know what is going on, and also handle postmaster death, since otherwise the loop might never terminate if the checkpointer has exited. Back-patch to 12. Although the problem exists in earlier releases too, the code is structured differently before 12 so I haven't gone any further for now, in the absence of field complaints. Reported-by: Andres Freund <andres@anarazel.de> Reviewed-by: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/20220226213942.nb7uvb2pamyu26dj%40alap3.anarazel.de
2022-03-03Fix bogus casting in BlockIdGetBlockNumber().Tom Lane
This macro cast the result to BlockNumber after shifting, not before, which is the wrong thing. Per the C spec, the uint16 fields would promote to int not unsigned int, so that (for 32-bit int) the shift potentially shifts a nonzero bit into the sign position. I doubt there are any production systems where this would actually end with the wrong answer, but it is undefined behavior per the C spec, and clang's -fsanitize=undefined option reputedly warns about it on some platforms. (I can't reproduce that right now, but the code is undeniably wrong per spec.) It's easy to fix by casting to BlockNumber (uint32) in the proper places. It's been wrong for ages, so back-patch to all supported branches. Report and patch by Zhihong Yu (cosmetic tweaking by me) Discussion: https://postgr.es/m/CALNJ-vT9r0DSsAOw9OXVJFxLENoVS_68kJ5x0p44atoYH+H4dg@mail.gmail.com
2022-02-17Suppress warning about stack_base_ptr with late-model GCC.Tom Lane
GCC 12 complains that set_stack_base is storing the address of a local variable in a long-lived pointer. This is an entirely reasonable warning (indeed, it just helped us find a bug); but that behavior is intentional here. We can work around it by using __builtin_frame_address(0) instead of a specific local variable; that produces an address a dozen or so bytes different, in my testing, but we don't care about such a small difference. Maybe someday a compiler lacking that function will start to issue a similar warning, but we'll worry about that when it happens. Patch by me, per a suggestion from Andres Freund. Back-patch to v12, which is as far back as the patch will go without some pain. (Recently-established project policy would permit a back-patch as far as 9.2, but I'm disinclined to expend the work until GCC 12 is much more widespread.) Discussion: https://postgr.es/m/3773792.1645141467@sss.pgh.pa.us
2022-01-29Fix failure to validate the result of select_common_type().Tom Lane
Although select_common_type() has a failure-return convention, an apparent successful return just provides a type OID that *might* work as a common supertype; we've not validated that the required casts actually exist. In the mainstream use-cases that doesn't matter, because we'll proceed to invoke coerce_to_common_type() on each input, which will fail appropriately if the proposed common type doesn't actually work. However, a few callers didn't read the (nonexistent) fine print, and thought that if they got back a nonzero OID then the coercions were sure to work. This affects in particular the recently-added "anycompatible" polymorphic types; we might think that a function/operator using such types matches cases it really doesn't. A likely end result of that is unexpected "ambiguous operator" errors, as for example in bug #17387 from James Inform. Another, much older, case is that the parser might try to transform an "x IN (list)" construct to a ScalarArrayOpExpr even when the list elements don't actually have a common supertype. It doesn't seem desirable to add more checking to select_common_type itself, as that'd just slow down the mainstream use-cases. Instead, write a separate function verify_common_type that performs the missing checks, and add a call to that where necessary. Likewise add verify_common_type_from_oids to go with select_common_type_from_oids. Back-patch to v13 where the "anycompatible" types came in. (The symptom complained of in bug #17387 doesn't appear till v14, but that's just because we didn't get around to converting || to use anycompatible till then.) In principle the "x IN (list)" fix could go back all the way, but I'm not currently convinced that it makes much difference in real-world cases, so I won't bother for now. Discussion: https://postgr.es/m/17387-5dfe54b988444963@postgresql.org
2022-01-27Fix ordering of XIDs in ProcArrayApplyRecoveryInfoTomas Vondra
Commit 8431e296ea reworked ProcArrayApplyRecoveryInfo to sort XIDs before adding them to KnownAssignedXids. But the XIDs are sorted using xidComparator, which compares the XIDs simply as uint32 values, not logically. KnownAssignedXidsAdd() however expects XIDs in logical order, and calls TransactionIdFollowsOrEquals() to enforce that. If there are XIDs for which the two orderings disagree, an error is raised and the recovery fails/restarts. Hitting this issue is fairly easy - you just need two transactions, one started before the 4B limit (e.g. XID 4294967290), the other sometime after it (e.g. XID 1000). Logically (4294967290 <= 1000) but when compared using xidComparator we try to add them in the opposite order. Which makes KnownAssignedXidsAdd() fail with an error like this: ERROR: out-of-order XID insertion in KnownAssignedXids This only happens during replica startup, while processing RUNNING_XACTS records to build the snapshot. Once we reach STANDBY_SNAPSHOT_READY, we skip these records. So this does not affect already running replicas, but if you restart (or create) a replica while there are transactions with XIDs for which the two orderings disagree, you may hit this. Long-running transactions and frequent replica restarts increase the likelihood of hitting this issue. Once the replica gets into this state, it can't be started (even if the old transactions are terminated). Fixed by sorting the XIDs logically - this is fine because we're dealing with normal XIDs (because it's XIDs assigned to backends) and from the same wraparound epoch (otherwise the backends could not be running at the same time on the primary node). So there are no problems with the triangle inequality, which is why xidComparator compares raw values. Investigation and root cause analysis by Abhijit Menon-Sen. Patch by me. This issue is present in all releases since 9.4, however releases up to 9.6 are EOL already so backpatch to 10 only. Reviewed-by: Abhijit Menon-Sen Reviewed-by: Alvaro Herrera Backpatch-through: 10 Discussion: https://postgr.es/m/36b8a501-5d73-277c-4972-f58a4dce088a%40enterprisedb.com
2022-01-24Fix limitations on what SQL commands can be issued to a walsender.Tom Lane
In logical replication mode, a WalSender is supposed to be able to execute any regular SQL command, as well as the special replication commands. Poor design of the replication-command parser caused it to fail in various cases, notably: * semicolons embedded in a command, or multiple SQL commands sent in a single message; * dollar-quoted literals containing odd numbers of single or double quote marks; * commands starting with a comment. The basic problem here is that we're trying to run repl_scanner.l across the entire input string even when it's not a replication command. Since repl_scanner.l does not understand all of the token types known to the core lexer, this is doomed to have failure modes. We certainly don't want to make repl_scanner.l as big as scan.l, so instead rejigger stuff so that we only lex the first token of a non-replication command. That will usually look like an IDENT to repl_scanner.l, though a comment would end up getting reported as a '-' or '/' single-character token. If the token is a replication command keyword, we push it back and proceed normally with repl_gram.y parsing. Otherwise, we can drop out of exec_replication_command() without examining the rest of the string. (It's still theoretically possible for repl_scanner.l to fail on the first token; but that could only happen if it's an unterminated single- or double-quoted string, in which case you'd have gotten largely the same error from the core lexer too.) In this way, repl_gram.y isn't involved at all in handling general SQL commands, so we can get rid of the SQLCmd node type. (In the back branches, we can't remove it because renumbering enum NodeTag would be an ABI break; so just leave it sit there unused.) I failed to resist the temptation to clean up some other sloppy coding in repl_scanner.l while at it. The only externally-visible behavior change from that is it now accepts \r and \f as whitespace, same as the core lexer. Per bug #17379 from Greg Rychlewski. Back-patch to all supported branches. Discussion: https://postgr.es/m/17379-6a5c6cfb3f1f5e77@postgresql.org
2022-01-03Fix index-only scan plans, take 2.Tom Lane
Commit 4ace45677 failed to fix the problem fully, because the same issue of attempting to fetch a non-returnable index column can occur when rechecking the indexqual after using a lossy index operator. Moreover, it broke EXPLAIN for such indexquals (which indicates a gap in our test cases :-(). Revert the code changes of 4ace45677 in favor of adding a new field to struct IndexOnlyScan, containing a version of the indexqual that can be executed against the index-returned tuple without using any non-returnable columns. (The restrictions imposed by check_index_only guarantee this is possible, although we may have to recompute indexed expressions.) Support construction of that during setrefs.c processing by marking IndexOnlyScan.indextlist entries as resjunk if they can't be returned, rather than removing them entirely. (We could alternatively require setrefs.c to look up the IndexOptInfo again, but abusing resjunk this way seems like a reasonably safe way to avoid needing to do that.) This solution isn't great from an API-stability standpoint: if there are any extensions out there that build IndexOnlyScan structs directly, they'll be broken in the next minor releases. However, only a very invasive extension would be likely to do such a thing. There's no change in the Path representation, so typical planner extensions shouldn't have a problem. As before, back-patch to all supported branches. Discussion: https://postgr.es/m/3179992.1641150853@sss.pgh.pa.us Discussion: https://postgr.es/m/17350-b5bdcf476e5badbb@postgresql.org
2022-01-01Fix index-only scan plans when not all index columns can be returned.Tom Lane
If an index has both returnable and non-returnable columns, and one of the non-returnable columns is an expression using a Var that is in a returnable column, then a query returning that expression could result in an index-only scan plan that attempts to read the non-returnable column, instead of recomputing the expression from the returnable column as intended. To fix, redefine the "indextlist" list of an IndexOnlyScan plan node as containing null Consts in place of any non-returnable columns. This solves the problem by preventing setrefs.c from falsely matching to such entries. The executor is happy since it only cares about the exposed types of the entries, and ruleutils.c doesn't care because a correct plan won't reference those entries. I considered some other ways to prevent setrefs.c from doing the wrong thing, but this way seems good since (a) it allows a very localized fix, (b) it makes the indextlist structure more compact in many cases, and (c) the indextlist is now a more faithful representation of what the index AM will actually produce, viz. nulls for any non-returnable columns. This is easier to hit since we introduced included columns, but it's possible to construct failing examples without that, as per the added regression test. Hence, back-patch to all supported branches. Per bug #17350 from Louis Jachiet. Discussion: https://postgr.es/m/17350-b5bdcf476e5badbb@postgresql.org
2021-12-22Correct comment and some documentation about REPLICA_IDENTITY_INDEXMichael Paquier
catalog/pg_class.h was stating that REPLICA_IDENTITY_INDEX with a dropped index is equivalent to REPLICA_IDENTITY_DEFAULT. The code tells a different story, as it is equivalent to REPLICA_IDENTITY_NOTHING. The behavior exists since the introduction of replica identities, and fe7fd4e even added tests for this case but I somewhat forgot to fix this comment. While on it, this commit reorganizes the documentation about replica identities on the ALTER TABLE page, and a note is added about the case of dropped indexes with REPLICA_IDENTITY_INDEX. Author: Michael Paquier, Wei Wang Reviewed-by: Euler Taveira Discussion: https://postgr.es/m/OS3PR01MB6275464AD0A681A0793F56879E759@OS3PR01MB6275.jpnprd01.prod.outlook.com Backpatch-through: 10
2021-11-26Harden be-gssapi-common.h for headerscheckAlvaro Herrera
Surround the contents with a test that the feature is enabled by configure, to silence header checking tools on systems without GSSAPI installed. Backpatch to 12, where the file appeared. Discussion: https://postgr.es/m/202111161709.u3pbx5lxdimt@alvherre.pgsql
2021-11-19Fix parallel operations that prevent oldest xmin from advancing.Amit Kapila
While determining xid horizons, we skip over backends that are running Vacuum. We also ignore Create Index Concurrently, or Reindex Concurrently for the purposes of computing Xmin for Vacuum. But we were not setting the flags corresponding to these operations when they are performed in parallel which was preventing Xid horizon from advancing. The optimization related to skipping Create Index Concurrently, or Reindex Concurrently operations was implemented in PG-14 but the fix is the same for the Parallel Vacuum as well so back-patched till PG-13. Author: Masahiko Sawada Reviewed-by: Amit Kapila Backpatch-through: 13 Discussion: https://postgr.es/m/CAD21AoCLQqgM1sXh9BrDFq0uzd3RBFKi=Vfo6cjjKODm0Onr5w@mail.gmail.com
2021-11-08Reject extraneous data after SSL or GSS encryption handshake.Tom Lane
The server collects up to a bufferload of data whenever it reads data from the client socket. When SSL or GSS encryption is requested during startup, any additional data received with the initial request message remained in the buffer, and would be treated as already-decrypted data once the encryption handshake completed. Thus, a man-in-the-middle with the ability to inject data into the TCP connection could stuff some cleartext data into the start of a supposedly encryption-protected database session. This could be abused to send faked SQL commands to the server, although that would only work if the server did not demand any authentication data. (However, a server relying on SSL certificate authentication might well not do so.) To fix, throw a protocol-violation error if the internal buffer is not empty after the encryption handshake. Our thanks to Jacob Champion for reporting this problem. Security: CVE-2021-23214
2021-11-02Avoid O(N^2) behavior in SyncPostCheckpoint().Tom Lane
As in commits 6301c3ada and e9d9ba2a4, avoid doing repetitive list_delete_first() operations, since that would be expensive when there are many files waiting to be unlinked. This is a slightly larger change than in those cases. We have to keep the list state valid for calls to AbsorbSyncRequests(), so it's necessary to invent a "canceled" field instead of immediately deleting PendingUnlinkEntry entries. Also, because we might not be able to process all the entries, we need a new list primitive list_delete_first_n(). list_delete_first_n() is almost list_copy_tail(), but it modifies the input List instead of making a new copy. I found a couple of existing uses of the latter that could profitably use the new function. (There might be more, but the other callers look like they probably shouldn't overwrite the input List.) As before, back-patch to v13. Discussion: https://postgr.es/m/CD2F0E7F-9822-45EC-A411-AE56F14DEA9F@amazon.com
2021-10-23Fix CREATE INDEX CONCURRENTLY for the newest prepared transactions.Noah Misch
The purpose of commit 8a54e12a38d1545d249f1402f66c8cde2837d97c was to fix this, and it sufficed when the PREPARE TRANSACTION completed before the CIC looked for lock conflicts. Otherwise, things still broke. As before, in a cluster having used CIC while having enabled prepared transactions, queries that use the resulting index can silently fail to find rows. It may be necessary to reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices. Fix this for future index builds by making CIC wait for arbitrarily-recent prepared transactions and for ordinary transactions that may yet PREPARE TRANSACTION. As part of that, have PREPARE TRANSACTION transfer locks to its dummy PGPROC before it calls ProcArrayClearTransaction(). Back-patch to 9.6 (all supported versions). Andrey Borodin, reviewed (in earlier versions) by Andres Freund. Discussion: https://postgr.es/m/01824242-AA92-4FE9-9BA7-AEBAFFEA3D0C@yandex-team.ru