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[PATCH 03/10] Make sure published XIDs are persistent 3+ messages / 3 participants [nested] [flat]
* [PATCH 03/10] Make sure published XIDs are persistent @ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]> 0 siblings, 0 replies; 3+ messages in thread From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw) pg_xact_status() premises that XIDs obtained by pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But XIDs are not guaranteed to go beyond WAL buffers before commit and thus XIDs may vanish if server crashes before commit. This patch guarantees the XID shown by the functions to be flushed out to disk. Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com --- src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------ src/backend/access/transam/xlog.c | 2 +- src/backend/utils/adt/xid8funcs.c | 12 ++++++- src/include/access/xact.h | 3 +- 4 files changed, 59 insertions(+), 13 deletions(-) diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 6395a9b240..38e978d238 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -201,7 +201,7 @@ typedef struct TransactionStateData int prevSecContext; /* previous SecurityRestrictionContext */ bool prevXactReadOnly; /* entry-time xact r/o state */ bool startedInRecovery; /* did we start in recovery? */ - bool didLogXid; /* has xid been included in WAL record? */ + XLogRecPtr minLSN; /* LSN needed to reach to record the xid */ int parallelModeLevel; /* Enter/ExitParallelMode counter */ bool chain; /* start a new block after this one */ bool assigned; /* assigned to top-level XID */ @@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void) * MarkCurrentTransactionIdLoggedIfAny * * Remember that the current xid - if it is assigned - now has been wal logged. + * + * upto is the LSN up to which we need to flush WAL to ensure the current xid + * to be persistent. See EnsureCurrentTransactionIdLogged(). */ void -MarkCurrentTransactionIdLoggedIfAny(void) +MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto) { - if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId)) - CurrentTransactionState->didLogXid = true; + if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) && + XLogRecPtrIsInvalid(CurrentTransactionState->minLSN)) + CurrentTransactionState->minLSN = upto; } +/* + * EnsureCurrentTransactionIdLogged + * + * Make sure that the current top XID is WAL-logged. + */ +void +EnsureTopTransactionIdLogged(void) +{ + /* + * We need at least one WAL record for the current top transaction to be + * flushed out. Write one if we don't have one yet. + */ + if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN)) + { + xl_xact_assignment xlrec; + + xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId); + Assert(TransactionIdIsValid(xlrec.xtop)); + xlrec.nsubxacts = 0; + + XLogBeginInsert(); + XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment); + TopTransactionStateData.minLSN = + XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT); + } + + XLogFlush(TopTransactionStateData.minLSN); +} /* * GetStableLatestTransactionId @@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s) * When wal_level=logical, guarantee that a subtransaction's xid can only * be seen in the WAL stream if its toplevel xid has been logged before. * If necessary we log an xact_assignment record with fewer than - * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set + * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set * for a transaction even though it appears in a WAL record, we just might * superfluously log something. That can happen when an xid is included * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in * xl_standby_locks. */ if (isSubXact && XLogLogicalInfoActive() && - !TopTransactionStateData.didLogXid) + XLogRecPtrIsInvalid(TopTransactionStateData.minLSN)) log_unknown_top = true; /* @@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s) log_unknown_top) { xl_xact_assignment xlrec; + XLogRecPtr endptr; /* * xtop is always set by now because we recurse up transaction @@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s) XLogRegisterData((char *) unreportedXids, nUnreportedXids * sizeof(TransactionId)); - (void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT); + endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT); nUnreportedXids = 0; - /* mark top, not current xact as having been logged */ - TopTransactionStateData.didLogXid = true; + + /* set minLSN of top, not of current xact if not yet */ + if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN)) + TopTransactionStateData.minLSN = endptr; } } } @@ -2022,7 +2057,7 @@ StartTransaction(void) * initialize reported xid accounting */ nUnreportedXids = 0; - s->didLogXid = false; + s->minLSN = InvalidXLogRecPtr; /* * must initialize resource-management stuff first diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 04192b7add..0183589b4d 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata, */ WALInsertLockRelease(); - MarkCurrentTransactionIdLoggedIfAny(); + MarkCurrentTransactionIdLoggedIfAny(EndPos); END_CRIT_SECTION(); diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c index cc2b4ac797..992482f8c8 100644 --- a/src/backend/utils/adt/xid8funcs.c +++ b/src/backend/utils/adt/xid8funcs.c @@ -357,6 +357,8 @@ bad_format: Datum pg_current_xact_id(PG_FUNCTION_ARGS) { + FullTransactionId xid; + /* * Must prevent during recovery because if an xid is not assigned we try * to assign one, which would fail. Programs already rely on this function @@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS) */ PreventCommandDuringRecovery("pg_current_xact_id()"); - PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId()); + xid = GetTopFullTransactionId(); + + /* the XID is going to be published, make sure it is psersistent */ + EnsureTopTransactionIdLogged(); + + PG_RETURN_FULLTRANSACTIONID(xid); } /* @@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS) if (!FullTransactionIdIsValid(topfxid)) PG_RETURN_NULL(); + /* the XID is going to be published, make sure it is psersistent */ + EnsureTopTransactionIdLogged(); + PG_RETURN_FULLTRANSACTIONID(topfxid); } diff --git a/src/include/access/xact.h b/src/include/access/xact.h index 34cfaf542c..a61e4d6da5 100644 --- a/src/include/access/xact.h +++ b/src/include/access/xact.h @@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void); extern FullTransactionId GetTopFullTransactionIdIfAny(void); extern FullTransactionId GetCurrentFullTransactionId(void); extern FullTransactionId GetCurrentFullTransactionIdIfAny(void); -extern void MarkCurrentTransactionIdLoggedIfAny(void); +extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto); +extern void EnsureTopTransactionIdLogged(void); extern bool SubTransactionIsActive(SubTransactionId subxid); extern CommandId GetCurrentCommandId(bool used); extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts); -- 2.17.0 --0qVF/w3MHQqLSynd Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="0004-wal_compression_method-default-to-zlib.patch" ^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: pgsql: TAP test for logical decoding on standby @ 2023-05-23 15:15 Robert Haas <[email protected]> 0 siblings, 1 reply; 3+ messages in thread From: Robert Haas @ 2023-05-23 15:15 UTC (permalink / raw) To: Andres Freund <[email protected]>; +Cc: pgsql-hackers; Drouvot, Bertrand <[email protected]> On Sat, Apr 8, 2023 at 5:26 AM Andres Freund <[email protected]> wrote: > TAP test for logical decoding on standby Small nitpicks: 1. The test names generated by check_slots_conflicting_status() start with a capital letter, while most other test names start with a lower-case letter. 2. The function is called 7 times, 6 with a true argument and 1 with a false argument, but the test name only depends on whether the argument is true or false, so we get the same test name 6 times. Maybe there's not a reasonable way to do better, I'm not sure, but it's not ideal. -- Robert Haas EDB: http://www.enterprisedb.com ^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: pgsql: TAP test for logical decoding on standby @ 2023-05-24 11:58 Drouvot, Bertrand <[email protected]> parent: Robert Haas <[email protected]> 0 siblings, 0 replies; 3+ messages in thread From: Drouvot, Bertrand @ 2023-05-24 11:58 UTC (permalink / raw) To: Robert Haas <[email protected]>; Andres Freund <[email protected]>; +Cc: pgsql-hackers Hi, On 5/23/23 5:15 PM, Robert Haas wrote: > On Sat, Apr 8, 2023 at 5:26 AM Andres Freund <[email protected]> wrote: >> TAP test for logical decoding on standby > > Small nitpicks: > > 1. The test names generated by check_slots_conflicting_status() start > with a capital letter, while most other test names start with a > lower-case letter. > Yeah, not sure that would deserve a fix for its own but if we address 2. then let's do 1. too. > 2. The function is called 7 times, 6 with a true argument and 1 with a > false argument, but the test name only depends on whether the argument > is true or false, so we get the same test name 6 times. Maybe there's > not a reasonable way to do better, I'm not sure, but it's not ideal. > I agree that's not ideal (but one could still figure out which one is failing if any by looking at the perl script). If we want to "improve" this, what about passing a second argument that would provide more context in the test name? Regards, -- Bertrand Drouvot PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com ^ permalink raw reply [nested|flat] 3+ messages in thread
end of thread, other threads:[~2023-05-24 11:58 UTC | newest] Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2021-03-08 06:43 [PATCH 03/10] Make sure published XIDs are persistent Kyotaro Horiguchi <[email protected]> 2023-05-23 15:15 Re: pgsql: TAP test for logical decoding on standby Robert Haas <[email protected]> 2023-05-24 11:58 ` Re: pgsql: TAP test for logical decoding on standby Drouvot, Bertrand <[email protected]>
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