>From 7d83bd78b7ca0bad52a6d54a996b8fe8c15b4f65 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Tue, 22 Sep 2015 15:17:09 +0200 Subject: [PATCH 3/3] Rework the way multixact truncations work. The fact that multixact truncations are not WAL logged has caused a fair share of problems. Amongst others it requires to do computations during recovery while the database is not in a consistent state, delaying truncations till checkpoints, and handling members being truncated, but offset not. We tried to put bandaids on lots of these issues over the last years, but it seems time to change course. Thus this patch introduces WAL logging for truncation, even in the back branches. This allows: 1) to perform the truncation directly during VACUUM, instead of delaying it to the checkpoint. 2) to avoid looking at the offsets SLRU for truncation during recovery, we can just use the master's values. 3) simplify a fair amount of logic to keep in memory limits straight, this has gotten much easier During the course of fixing this a bunch of bugs had to be fixed: 1) Data was not purged from memory the member's slru before deleting segments. This happend to be hard or impossible to hit due to the interlock between checkpoints and truncation. 2) find_multixact_start() relied on SimpleLruDoesPhysicalPageExist - but that doesn't work for offsets that haven't yet been flushed to disk. Flush out before running to fix. Not pretty, but it feels slightly safer to only make decisions based on on-disk state. 3) find_multixact_start() could be called concurrently with a truncation and thus fail. Via SetOffsetVacuumLimit() that could lead to a round of emergency vacuuming. The problem remains in pg_get_multixact_members(), but that's quite harmless. To handle the case of an updated standby replaying WAL from a not-yet upgraded primary we have to recognize that situation and use "old style" truncation (i.e. looking at the SLRUs) during WAL replay. In contrast to before this now happens in the startup process, when replaying a checkpoint record, instead of the checkpointer. Doing this in the restartpoint was incorrect, they can happen much later than the original checkpoint, thereby leading to wraparound. It's also more in line to how the WAL logging now works. To avoid "multixact_redo: unknown op code 48" errors standbys should be upgraded before primaries. This needs to be expressed clearly in the release notes. Backpatch to 9.3, where the use of multixacts was expanded. Arguably this could be backpatched further, but there doesn't seem to be sufficient benefit to outweigh the risk of applying a significantly different patch there. Discussion: 20150621192409.GA4797@alap3.anarazel.de Reviewed-By: Robert Haas, Alvaro Herrera, Thomas Munro Backpatch: 9.3 --- src/backend/access/rmgrdesc/mxactdesc.c | 11 + src/backend/access/transam/multixact.c | 651 ++++++++++++++++++------------- src/backend/access/transam/slru.c | 83 +++- src/backend/access/transam/xlog.c | 53 +-- src/backend/commands/vacuum.c | 4 +- src/backend/storage/lmgr/lwlocknames.txt | 1 + src/include/access/multixact.h | 19 +- src/include/access/slru.h | 4 +- src/tools/pgindent/typedefs.list | 1 + 9 files changed, 507 insertions(+), 320 deletions(-) diff --git a/src/backend/access/rmgrdesc/mxactdesc.c b/src/backend/access/rmgrdesc/mxactdesc.c index 572951e..5b8134f 100644 --- a/src/backend/access/rmgrdesc/mxactdesc.c +++ b/src/backend/access/rmgrdesc/mxactdesc.c @@ -70,6 +70,14 @@ multixact_desc(StringInfo buf, XLogReaderState *record) for (i = 0; i < xlrec->nmembers; i++) out_member(buf, &xlrec->members[i]); } + else if (info == XLOG_MULTIXACT_TRUNCATE_ID) + { + xl_multixact_truncate *xlrec = (xl_multixact_truncate *) rec; + + appendStringInfo(buf, "offsets [%u, %u), members [%u, %u)", + xlrec->startTruncOff, xlrec->endTruncOff, + xlrec->startTruncMemb, xlrec->endTruncMemb); + } } const char * @@ -88,6 +96,9 @@ multixact_identify(uint8 info) case XLOG_MULTIXACT_CREATE_ID: id = "CREATE_ID"; break; + case XLOG_MULTIXACT_TRUNCATE_ID: + id = "TRUNCATE_ID"; + break; } return id; diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c index 34c5370..1c3cfbe 100644 --- a/src/backend/access/transam/multixact.c +++ b/src/backend/access/transam/multixact.c @@ -49,9 +49,7 @@ * value is removed; the cutoff value is stored in pg_class. The minimum value * across all tables in each database is stored in pg_database, and the global * minimum across all databases is part of pg_control and is kept in shared - * memory. At checkpoint time, after the value is known flushed in WAL, any - * files that correspond to multixacts older than that value are removed. - * (These files are also removed when a restartpoint is executed.) + * memory. Whenever that minimum is advanced, the SLRUs are truncated. * * When new multixactid values are to be created, care is taken that the * counter does not fall within the wraparound horizon considering the global @@ -83,6 +81,7 @@ #include "postmaster/autovacuum.h" #include "storage/lmgr.h" #include "storage/pmsignal.h" +#include "storage/proc.h" #include "storage/procarray.h" #include "utils/builtins.h" #include "utils/memutils.h" @@ -109,6 +108,7 @@ ((xid) / (MultiXactOffset) MULTIXACT_OFFSETS_PER_PAGE) #define MultiXactIdToOffsetEntry(xid) \ ((xid) % (MultiXactOffset) MULTIXACT_OFFSETS_PER_PAGE) +#define MultiXactIdToOffsetSegment(xid) (MultiXactIdToOffsetPage(xid) / SLRU_PAGES_PER_SEGMENT) /* * The situation for members is a bit more complex: we store one byte of @@ -153,6 +153,7 @@ /* page in which a member is to be found */ #define MXOffsetToMemberPage(xid) ((xid) / (TransactionId) MULTIXACT_MEMBERS_PER_PAGE) +#define MXOffsetToMemberSegment(xid) (MXOffsetToMemberPage(xid) / SLRU_PAGES_PER_SEGMENT) /* Location (byte offset within page) of flag word for a given member */ #define MXOffsetToFlagsOffset(xid) \ @@ -220,11 +221,12 @@ typedef struct MultiXactStateData bool oldestOffsetKnown; /* - * This is what the previous checkpoint stored as the truncate position. - * This value is the oldestMultiXactId that was valid when a checkpoint - * was last executed. + * True if a multixact truncation WAL record was replayed since the last + * checkpoint. This is used to trigger 'legacy truncations', i.e. truncate + * by looking at the data directory during WAL replay, when the primary is + * too old to generate truncation records. */ - MultiXactId lastCheckpointedOldest; + bool sawTruncationInCkptCycle; /* support for anti-wraparound measures */ MultiXactId multiVacLimit; @@ -233,8 +235,7 @@ typedef struct MultiXactStateData MultiXactId multiWrapLimit; /* support for members anti-wraparound measures */ - MultiXactOffset offsetStopLimit; - bool offsetStopLimitKnown; + MultiXactOffset offsetStopLimit; /* known if oldestOffsetKnown */ /* * Per-backend data starts here. We have two arrays stored in the area @@ -364,12 +365,14 @@ static bool MultiXactOffsetPrecedes(MultiXactOffset offset1, MultiXactOffset offset2); static void ExtendMultiXactOffset(MultiXactId multi); static void ExtendMultiXactMember(MultiXactOffset offset, int nmembers); -static void DetermineSafeOldestOffset(MultiXactId oldestMXact); static bool MultiXactOffsetWouldWrap(MultiXactOffset boundary, MultiXactOffset start, uint32 distance); -static bool SetOffsetVacuumLimit(bool finish_setup); +static bool SetOffsetVacuumLimit(void); static bool find_multixact_start(MultiXactId multi, MultiXactOffset *result); static void WriteMZeroPageXlogRec(int pageno, uint8 info); +static void WriteMTruncateXlogRec(Oid oldestMultiDB, + MultiXactId startOff, MultiXactId endOff, + MultiXactOffset startMemb, MultiXactOffset endMemb); /* @@ -1102,7 +1105,7 @@ GetNewMultiXactId(int nmembers, MultiXactOffset *offset) *---------- */ #define OFFSET_WARN_SEGMENTS 20 - if (MultiXactState->offsetStopLimitKnown && + if (MultiXactState->oldestOffsetKnown && MultiXactOffsetWouldWrap(MultiXactState->offsetStopLimit, nextOffset, nmembers)) { @@ -1142,7 +1145,7 @@ GetNewMultiXactId(int nmembers, MultiXactOffset *offset) SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_LAUNCHER); } - if (MultiXactState->offsetStopLimitKnown && + if (MultiXactState->oldestOffsetKnown && MultiXactOffsetWouldWrap(MultiXactState->offsetStopLimit, nextOffset, nmembers + MULTIXACT_MEMBERS_PER_PAGE * SLRU_PAGES_PER_SEGMENT * OFFSET_WARN_SEGMENTS)) @@ -2020,13 +2023,21 @@ StartupMultiXact(void) void TrimMultiXact(void) { - MultiXactId multi = MultiXactState->nextMXact; - MultiXactOffset offset = MultiXactState->nextOffset; - MultiXactId oldestMXact; + MultiXactId nextMXact; + MultiXactOffset offset; + MultiXactId oldestMXact; + Oid oldestMXactDB; int pageno; int entryno; int flagsoff; + LWLockAcquire(MultiXactGenLock, LW_EXCLUSIVE); + nextMXact = MultiXactState->nextMXact; + offset = MultiXactState->nextOffset; + oldestMXact = MultiXactState->oldestMultiXactId; + oldestMXactDB = MultiXactState->oldestMultiXactDB; + MultiXactState->finishedStartup = true; + LWLockRelease(MultiXactGenLock); /* Clean up offsets state */ LWLockAcquire(MultiXactOffsetControlLock, LW_EXCLUSIVE); @@ -2034,20 +2045,20 @@ TrimMultiXact(void) /* * (Re-)Initialize our idea of the latest page number for offsets. */ - pageno = MultiXactIdToOffsetPage(multi); + pageno = MultiXactIdToOffsetPage(nextMXact); MultiXactOffsetCtl->shared->latest_page_number = pageno; /* * Zero out the remainder of the current offsets page. See notes in * TrimCLOG() for motivation. */ - entryno = MultiXactIdToOffsetEntry(multi); + entryno = MultiXactIdToOffsetEntry(nextMXact); if (entryno != 0) { int slotno; MultiXactOffset *offptr; - slotno = SimpleLruReadPage(MultiXactOffsetCtl, pageno, true, multi); + slotno = SimpleLruReadPage(MultiXactOffsetCtl, pageno, true, nextMXact); offptr = (MultiXactOffset *) MultiXactOffsetCtl->shared->page_buffer[slotno]; offptr += entryno; @@ -2096,12 +2107,11 @@ TrimMultiXact(void) LWLockRelease(MultiXactMemberControlLock); - if (SetOffsetVacuumLimit(true) && IsUnderPostmaster) - SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_LAUNCHER); - LWLockAcquire(MultiXactGenLock, LW_SHARED); - oldestMXact = MultiXactState->lastCheckpointedOldest; - LWLockRelease(MultiXactGenLock); - DetermineSafeOldestOffset(oldestMXact); + /* + * Now that we are fully started we can accurately compute how far the + * next members wraparound is away. + */ + SetMultiXactIdLimit(oldestMXact, oldestMXactDB); } /* @@ -2270,8 +2280,20 @@ SetMultiXactIdLimit(MultiXactId oldest_datminmxid, Oid oldest_datoid) (errmsg("MultiXactId wrap limit is %u, limited by database with OID %u", multiWrapLimit, oldest_datoid))); + /* + * Computing the actual limits is only possible once the data directory is + * in a consistent state. There's no need to compute the limits while + * still replaying WAL - no decisions about new multis are made even + * though multixact creations might be replayed. So we'll only do further + * checks after TrimMultiXact() has been called. + */ + if (!MultiXactState->finishedStartup) + return; + + Assert(!InRecovery); + /* Set limits for offset vacuum. */ - needs_offset_vacuum = SetOffsetVacuumLimit(false); + needs_offset_vacuum = SetOffsetVacuumLimit(); /* * If past the autovacuum force point, immediately signal an autovac @@ -2281,11 +2303,11 @@ SetMultiXactIdLimit(MultiXactId oldest_datminmxid, Oid oldest_datoid) * another iteration immediately if there are still any old databases. */ if ((MultiXactIdPrecedes(multiVacLimit, curMulti) || - needs_offset_vacuum) && IsUnderPostmaster && !InRecovery) + needs_offset_vacuum) && IsUnderPostmaster) SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_LAUNCHER); /* Give an immediate warning if past the wrap warn point */ - if (MultiXactIdPrecedes(multiWarnLimit, curMulti) && !InRecovery) + if (MultiXactIdPrecedes(multiWarnLimit, curMulti)) { char *oldest_datname; @@ -2353,27 +2375,39 @@ MultiXactAdvanceNextMXact(MultiXactId minMulti, } /* - * Update our oldestMultiXactId value, but only if it's more recent than - * what we had. However, even if not, always update the oldest multixact - * offset limit. + * Update our oldestMultiXactId value, but only if it's more recent than what + * we had. + * + * This may only be called during WAL replay. */ void MultiXactAdvanceOldest(MultiXactId oldestMulti, Oid oldestMultiDB) { + Assert(InRecovery); + if (MultiXactIdPrecedes(MultiXactState->oldestMultiXactId, oldestMulti)) + { + /* + * If there has been a truncation on the master, detected by seing a + * moving oldestMulti without a corresponding truncation record, we + * know that the primary is still running an older version of postgres + * that doesn't yet log multixact truncations. So perform truncation + * ourselves. + */ + if (!MultiXactState->sawTruncationInCkptCycle) + { + ereport(LOG, + (errmsg("performing legacy multixact truncation"), + errdetail("Legacy truncations are sometimes performed when replaying WAL from an older primary."), + errhint("Upgrade the primary, it is susceptible to data corruption."))); + TruncateMultiXact(oldestMulti, oldestMultiDB, true); + } + SetMultiXactIdLimit(oldestMulti, oldestMultiDB); -} + } -/* - * Update the "safe truncation point". This is the newest value of oldestMulti - * that is known to be flushed as part of a checkpoint record. - */ -void -MultiXactSetSafeTruncate(MultiXactId safeTruncateMulti) -{ - LWLockAcquire(MultiXactGenLock, LW_EXCLUSIVE); - MultiXactState->lastCheckpointedOldest = safeTruncateMulti; - LWLockRelease(MultiXactGenLock); + /* only looked at in the startup process, no lock necessary */ + MultiXactState->sawTruncationInCkptCycle = false; } /* @@ -2529,126 +2563,50 @@ GetOldestMultiXactId(void) } /* - * Based on the given oldest MultiXactId, determine what's the oldest member - * offset and install the limit info in MultiXactState, where it can be used to - * prevent overrun of old data in the members SLRU area. - */ -static void -DetermineSafeOldestOffset(MultiXactId oldestMXact) -{ - MultiXactOffset oldestOffset; - MultiXactOffset nextOffset; - MultiXactOffset offsetStopLimit; - MultiXactOffset prevOffsetStopLimit; - MultiXactId nextMXact; - bool finishedStartup; - bool prevOffsetStopLimitKnown; - - /* Fetch values from shared memory. */ - LWLockAcquire(MultiXactGenLock, LW_SHARED); - finishedStartup = MultiXactState->finishedStartup; - nextMXact = MultiXactState->nextMXact; - nextOffset = MultiXactState->nextOffset; - prevOffsetStopLimit = MultiXactState->offsetStopLimit; - prevOffsetStopLimitKnown = MultiXactState->offsetStopLimitKnown; - LWLockRelease(MultiXactGenLock); - - /* Don't worry about this until after we've started up. */ - if (!finishedStartup) - return; - - /* - * Determine the offset of the oldest multixact. Normally, we can read - * the offset from the multixact itself, but there's an important special - * case: if there are no multixacts in existence at all, oldestMXact - * obviously can't point to one. It will instead point to the multixact - * ID that will be assigned the next time one is needed. - * - * NB: oldestMXact should be the oldest multixact that still exists in the - * SLRU, unlike in SetOffsetVacuumLimit, where we do this same computation - * based on the oldest value that might be referenced in a table. - */ - if (nextMXact == oldestMXact) - oldestOffset = nextOffset; - else - { - bool oldestOffsetKnown; - - oldestOffsetKnown = find_multixact_start(oldestMXact, &oldestOffset); - if (!oldestOffsetKnown) - { - ereport(LOG, - (errmsg("MultiXact member wraparound protections are disabled because oldest checkpointed MultiXact %u does not exist on disk", - oldestMXact))); - return; - } - } - - /* move back to start of the corresponding segment */ - offsetStopLimit = oldestOffset - (oldestOffset % - (MULTIXACT_MEMBERS_PER_PAGE * SLRU_PAGES_PER_SEGMENT)); - /* always leave one segment before the wraparound point */ - offsetStopLimit -= (MULTIXACT_MEMBERS_PER_PAGE * SLRU_PAGES_PER_SEGMENT); - - /* if nothing has changed, we're done */ - if (prevOffsetStopLimitKnown && offsetStopLimit == prevOffsetStopLimit) - return; - - LWLockAcquire(MultiXactGenLock, LW_EXCLUSIVE); - MultiXactState->offsetStopLimit = offsetStopLimit; - MultiXactState->offsetStopLimitKnown = true; - LWLockRelease(MultiXactGenLock); - - if (!prevOffsetStopLimitKnown && IsUnderPostmaster) - ereport(LOG, - (errmsg("MultiXact member wraparound protections are now enabled"))); - ereport(DEBUG1, - (errmsg("MultiXact member stop limit is now %u based on MultiXact %u", - offsetStopLimit, oldestMXact))); -} - -/* * Determine how aggressively we need to vacuum in order to prevent member * wraparound. * - * To determine the oldest multixact ID, we look at oldestMultiXactId, not - * lastCheckpointedOldest. That's because vacuuming can't help with anything - * older than oldestMultiXactId; anything older than that isn't referenced - * by any table. Offsets older than oldestMultiXactId but not as old as - * lastCheckpointedOldest will go away after the next checkpoint. + * To do so determine what's the oldest member offset and install the limit + * info in MultiXactState, where it can be used to prevent overrun of old data + * in the members SLRU area. * * The return value is true if emergency autovacuum is required and false * otherwise. */ static bool -SetOffsetVacuumLimit(bool finish_setup) +SetOffsetVacuumLimit(void) { - MultiXactId oldestMultiXactId; + MultiXactId oldestMultiXactId; MultiXactId nextMXact; - bool finishedStartup; - MultiXactOffset oldestOffset = 0; /* placate compiler */ + MultiXactOffset oldestOffset = 0; /* placate compiler */ + MultiXactOffset prevOldestOffset; MultiXactOffset nextOffset; bool oldestOffsetKnown = false; - MultiXactOffset prevOldestOffset; bool prevOldestOffsetKnown; + MultiXactOffset offsetStopLimit = 0; + + /* + * NB: Have to prevent concurrent truncation, we might otherwise try to + * lookup a oldestMulti that's concurrently getting truncated away. + */ + LWLockAcquire(MultiXactTruncationLock, LW_SHARED); /* Read relevant fields from shared memory. */ LWLockAcquire(MultiXactGenLock, LW_SHARED); oldestMultiXactId = MultiXactState->oldestMultiXactId; nextMXact = MultiXactState->nextMXact; nextOffset = MultiXactState->nextOffset; - finishedStartup = MultiXactState->finishedStartup; - prevOldestOffset = MultiXactState->oldestOffset; prevOldestOffsetKnown = MultiXactState->oldestOffsetKnown; + prevOldestOffset = MultiXactState->oldestOffset; + Assert(MultiXactState->finishedStartup); LWLockRelease(MultiXactGenLock); - /* Don't do this until after any recovery is complete. */ - if (!finishedStartup && !finish_setup) - return false; - /* - * If no multixacts exist, then oldestMultiXactId will be the next - * multixact that will be created, rather than an existing multixact. + * Determine the offset of the oldest multixact. Normally, we can read + * the offset from the multixact itself, but there's an important special + * case: if there are no multixacts in existence at all, oldestMXact + * obviously can't point to one. It will instead point to the multixact + * ID that will be assigned the next time one is needed. */ if (oldestMultiXactId == nextMXact) { @@ -2669,39 +2627,45 @@ SetOffsetVacuumLimit(bool finish_setup) */ oldestOffsetKnown = find_multixact_start(oldestMultiXactId, &oldestOffset); + + if (oldestOffsetKnown) + ereport(DEBUG1, + (errmsg("oldest MultiXactId member is at offset %u", + oldestOffset))); + else + ereport(LOG, + (errmsg("MultiXact member wraparound protections are disabled because oldest checkpointed MultiXact %u does not exist on disk", + oldestMultiXactId))); } + LWLockRelease(MultiXactTruncationLock); + /* - * Except when initializing the system for the first time, there's no - * need to update anything if we don't know the oldest offset or if it - * hasn't changed. + * If we can, compute limits (and install them MultiXactState) to prevent + * overrun of old data in the members SLRU area. We can only do so if the + * oldest offset is known though. */ - if (finish_setup || - (oldestOffsetKnown && !prevOldestOffsetKnown) || - (oldestOffsetKnown && prevOldestOffset != oldestOffset)) + if (oldestOffsetKnown) { - /* Install the new limits. */ - LWLockAcquire(MultiXactGenLock, LW_EXCLUSIVE); - MultiXactState->oldestOffset = oldestOffset; - MultiXactState->oldestOffsetKnown = oldestOffsetKnown; - MultiXactState->finishedStartup = true; - LWLockRelease(MultiXactGenLock); + /* move back to start of the corresponding segment */ + offsetStopLimit = oldestOffset - (oldestOffset % + (MULTIXACT_MEMBERS_PER_PAGE * SLRU_PAGES_PER_SEGMENT)); - /* Log the info */ - if (oldestOffsetKnown) - ereport(DEBUG1, - (errmsg("oldest MultiXactId member is at offset %u", - oldestOffset))); - else - ereport(DEBUG1, - (errmsg("oldest MultiXactId member offset unknown"))); + /* always leave one segment before the wraparound point */ + offsetStopLimit -= (MULTIXACT_MEMBERS_PER_PAGE * SLRU_PAGES_PER_SEGMENT); + + if (!prevOldestOffsetKnown && IsUnderPostmaster) + ereport(LOG, + (errmsg("MultiXact member wraparound protections are now enabled"))); + ereport(DEBUG1, + (errmsg("MultiXact member stop limit is now %u based on MultiXact %u", + offsetStopLimit, oldestMultiXactId))); } /* * If we failed to get the oldest offset this time, but we have a value - * from a previous pass through this function, assess the need for - * autovacuum based on that old value rather than automatically forcing - * it. + * from a previous pass through this function, use the old value rather + * than automatically forcing it. */ if (prevOldestOffsetKnown && !oldestOffsetKnown) { @@ -2709,6 +2673,13 @@ SetOffsetVacuumLimit(bool finish_setup) oldestOffsetKnown = true; } + /* Install the computed values */ + LWLockAcquire(MultiXactGenLock, LW_EXCLUSIVE); + MultiXactState->oldestOffset = oldestOffset; + MultiXactState->oldestOffsetKnown = oldestOffsetKnown; + MultiXactState->offsetStopLimit = offsetStopLimit; + LWLockRelease(MultiXactGenLock); + /* * Do we need an emergency autovacuum? If we're not sure, assume yes. */ @@ -2723,7 +2694,7 @@ SetOffsetVacuumLimit(bool finish_setup) * boundary point, hence the name. The reason we don't want to use the regular * 2^31-modulo arithmetic here is that we want to be able to use the whole of * the 2^32-1 space here, allowing for more multixacts that would fit - * otherwise. See also SlruScanDirCbRemoveMembers. + * otherwise. */ static bool MultiXactOffsetWouldWrap(MultiXactOffset boundary, MultiXactOffset start, @@ -2769,6 +2740,9 @@ MultiXactOffsetWouldWrap(MultiXactOffset boundary, MultiXactOffset start, * * Returns false if the file containing the multi does not exist on disk. * Otherwise, returns true and sets *result to the starting member offset. + * + * This function does not prevent concurrent truncation, so if that's + * required, the caller has to protect against that. */ static bool find_multixact_start(MultiXactId multi, MultiXactOffset *result) @@ -2779,9 +2753,22 @@ find_multixact_start(MultiXactId multi, MultiXactOffset *result) int slotno; MultiXactOffset *offptr; + /* XXX: Remove || AmStartupProcess() after WAL page magic bump */ + Assert(MultiXactState->finishedStartup || AmStartupProcess()); + pageno = MultiXactIdToOffsetPage(multi); entryno = MultiXactIdToOffsetEntry(multi); + /* + * We need to flush out dirty data, so PhysicalPageExists can work + * correctly, but SimpleLruFlush() is a pretty big hammer for that. + * Alternatively we could add a in-memory version of page exists, but + * find_multixact_start is called infrequently, and it doesn't seem bad to + * flush buffers to disk before truncation. + */ + SimpleLruFlush(MultiXactOffsetCtl, true); + SimpleLruFlush(MultiXactMemberCtl, true); + if (!SimpleLruDoesPhysicalPageExist(MultiXactOffsetCtl, pageno)) return false; @@ -2887,65 +2874,6 @@ MultiXactMemberFreezeThreshold(void) return multixacts - victim_multixacts; } -/* - * SlruScanDirectory callback. - * This callback deletes segments that are outside the range determined by - * the given page numbers. - * - * Both range endpoints are exclusive (that is, segments containing any of - * those pages are kept.) - */ -typedef struct MembersLiveRange -{ - int rangeStart; - int rangeEnd; -} MembersLiveRange; - -static bool -SlruScanDirCbRemoveMembers(SlruCtl ctl, char *filename, int segpage, - void *data) -{ - MembersLiveRange *range = (MembersLiveRange *) data; - MultiXactOffset nextOffset; - - if ((segpage == range->rangeStart) || - (segpage == range->rangeEnd)) - return false; /* easy case out */ - - /* - * To ensure that no segment is spuriously removed, we must keep track of - * new segments added since the start of the directory scan; to do this, - * we update our end-of-range point as we run. - * - * As an optimization, we can skip looking at shared memory if we know for - * certain that the current segment must be kept. This is so because - * nextOffset never decreases, and we never increase rangeStart during any - * one run. - */ - if (!((range->rangeStart > range->rangeEnd && - segpage > range->rangeEnd && segpage < range->rangeStart) || - (range->rangeStart < range->rangeEnd && - (segpage < range->rangeStart || segpage > range->rangeEnd)))) - return false; - - /* - * Update our idea of the end of the live range. - */ - LWLockAcquire(MultiXactGenLock, LW_SHARED); - nextOffset = MultiXactState->nextOffset; - LWLockRelease(MultiXactGenLock); - range->rangeEnd = MXOffsetToMemberPage(nextOffset); - - /* Recheck the deletion condition. If it still holds, perform deletion */ - if ((range->rangeStart > range->rangeEnd && - segpage > range->rangeEnd && segpage < range->rangeStart) || - (range->rangeStart < range->rangeEnd && - (segpage < range->rangeStart || segpage > range->rangeEnd))) - SlruDeleteSegment(ctl, filename); - - return false; /* keep going */ -} - typedef struct mxtruncinfo { int earliestExistingPage; @@ -2969,6 +2897,52 @@ SlruScanDirCbFindEarliest(SlruCtl ctl, char *filename, int segpage, void *data) return false; /* keep going */ } + +/* + * Delete member segments [oldest, newOldest) + */ +static void +PerformMembersTruncation(MultiXactOffset oldestOffset, MultiXactOffset newOldestOffset) +{ + const int maxsegment = MXOffsetToMemberSegment(MaxMultiXactOffset); + int startsegment = MXOffsetToMemberSegment(oldestOffset); + int endsegment = MXOffsetToMemberSegment(newOldestOffset); + int segment = startsegment; + + /* + * Delete all the segments but the last one. The last segment can still + * contain, possibly partially, valid data. + */ + while (segment != endsegment) + { + elog(DEBUG2, "truncating multixact members segment %x", segment); + SlruDeleteSegment(MultiXactMemberCtl, segment); + + /* move to next segment, handling wraparound correctly */ + if (segment == maxsegment) + segment = 0; + else + segment += 1; + } +} + +/* + * Delete offsets segments [oldest, newOldest) + */ +static void +PerformOffsetsTruncation(MultiXactId oldestMulti, MultiXactId newOldestMulti) +{ + /* + * We step back one multixact to avoid passing a cutoff page that hasn't + * been created yet in the rare case that oldestMulti would be the first + * item on a page and oldestMulti == nextMulti. In that case, if we + * didn't subtract one, we'd trigger SimpleLruTruncate's wraparound + * detection. + */ + SimpleLruTruncate(MultiXactOffsetCtl, + MultiXactIdToOffsetPage(PreviousMultiXactId(newOldestMulti))); +} + /* * Remove all MultiXactOffset and MultiXactMember segments before the oldest * ones still of interest. @@ -2979,27 +2953,54 @@ SlruScanDirCbFindEarliest(SlruCtl ctl, char *filename, int segpage, void *data) * xlog_redo() will already have called MultiXactAdvanceOldest(). Our * latest_page_number will already have been initialized by StartupMultiXact() * and kept up to date as new pages are zeroed. + * + * newOldestMulti is the oldest currently required multixact, newOldestMultiDB + * is one of the databases preventing newOldestMulti from increasing. */ void -TruncateMultiXact(void) +TruncateMultiXact(MultiXactId newOldestMulti, Oid newOldestMultiDB, bool in_recovery) { - MultiXactId oldestMXact; + MultiXactId oldestMulti; + MultiXactId nextMulti; + MultiXactOffset newOldestOffset; MultiXactOffset oldestOffset; - MultiXactId nextMXact; - MultiXactOffset nextOffset; + MultiXactOffset nextOffset; mxtruncinfo trunc; MultiXactId earliest; - MembersLiveRange range; - Assert(AmCheckpointerProcess() || AmStartupProcess() || - !IsPostmasterEnvironment); + /* + * Need to allow being called in recovery for backwards compatibility, + * when an updated standby replays WAL generated by a non-updated primary. + */ + Assert(in_recovery || !RecoveryInProgress()); + Assert(!in_recovery || AmStartupProcess()); + Assert(in_recovery || MultiXactState->finishedStartup); + + /* + * We can only allow one truncation to happen at once. Otherwise parts of + * members might vanish while we're doing lookups or similar. There's no + * need to have an interlock with creating new multis or such, since those + * are constrained by the limits (which only grow, never shrink). + */ + LWLockAcquire(MultiXactTruncationLock, LW_EXCLUSIVE); LWLockAcquire(MultiXactGenLock, LW_SHARED); - oldestMXact = MultiXactState->lastCheckpointedOldest; - nextMXact = MultiXactState->nextMXact; + nextMulti = MultiXactState->nextMXact; nextOffset = MultiXactState->nextOffset; + oldestMulti = MultiXactState->oldestMultiXactId; LWLockRelease(MultiXactGenLock); - Assert(MultiXactIdIsValid(oldestMXact)); + Assert(MultiXactIdIsValid(oldestMulti)); + + /* + * Make sure to only attempt truncation if there's values to truncate + * away. In normal processing values shouldn't go backwards, but there's + * some corner cases (due to bugs) where that's possible. + */ + if (MultiXactIdPrecedesOrEquals(newOldestMulti, oldestMulti)) + { + LWLockRelease(MultiXactTruncationLock); + return; + } /* * Note we can't just plow ahead with the truncation; it's possible that @@ -3007,6 +3008,9 @@ TruncateMultiXact(void) * going to attempt to read the offsets page to determine where to * truncate the members SLRU. So we first scan the directory to determine * the earliest offsets page number that we can read without error. + * + * NB: It's also possible that the page that oldestMulti is on has already + * been truncated away, and we crashed before updating oldestMulti. */ trunc.earliestExistingPage = -1; SlruScanDirectory(MultiXactOffsetCtl, SlruScanDirCbFindEarliest, &trunc); @@ -3014,19 +3018,10 @@ TruncateMultiXact(void) if (earliest < FirstMultiXactId) earliest = FirstMultiXactId; - /* - * If there's nothing to remove, we can bail out early. - * - * Due to bugs in early releases of PostgreSQL 9.3.X and 9.4.X, - * oldestMXact might point to a multixact that does not exist. - * Autovacuum will eventually advance it to a value that does exist, - * and we want to set a proper offsetStopLimit when that happens, - * so call DetermineSafeOldestOffset here even if we're not actually - * truncating. - */ - if (MultiXactIdPrecedes(oldestMXact, earliest)) + /* If there's nothing to remove, we can bail out early. */ + if (MultiXactIdPrecedes(oldestMulti, earliest)) { - DetermineSafeOldestOffset(oldestMXact); + LWLockRelease(MultiXactTruncationLock); return; } @@ -3038,46 +3033,95 @@ TruncateMultiXact(void) * already checked that it doesn't precede the earliest MultiXact on * disk. But if it fails, don't truncate anything, and log a message. */ - if (oldestMXact == nextMXact) + if (oldestMulti == nextMulti) oldestOffset = nextOffset; /* there are NO MultiXacts */ - else if (!find_multixact_start(oldestMXact, &oldestOffset)) + else if (!find_multixact_start(oldestMulti, &oldestOffset)) { ereport(LOG, (errmsg("oldest MultiXact %u not found, earliest MultiXact %u, skipping truncation", - oldestMXact, earliest))); + oldestMulti, earliest))); + LWLockRelease(MultiXactTruncationLock); return; } /* - * To truncate MultiXactMembers, we need to figure out the active page - * range and delete all files outside that range. The start point is the - * start of the segment containing the oldest offset; an end point of the - * segment containing the next offset to use is enough. The end point is - * updated as MultiXactMember gets extended concurrently, elsewhere. + * Secondly compute up to where to truncate. Lookup the corresponding + * member offset for newOldestMulti for that. */ - range.rangeStart = MXOffsetToMemberPage(oldestOffset); - range.rangeStart -= range.rangeStart % SLRU_PAGES_PER_SEGMENT; - - range.rangeEnd = MXOffsetToMemberPage(nextOffset); + if (newOldestMulti == nextMulti) + newOldestOffset = nextOffset; /* there are NO MultiXacts */ + else if (!find_multixact_start(newOldestMulti, &newOldestOffset)) + { + ereport(LOG, + (errmsg("cannot truncate up toMultiXact %u because it does not exist on disk, skipping truncation", + newOldestMulti))); + LWLockRelease(MultiXactTruncationLock); + return; + } - SlruScanDirectory(MultiXactMemberCtl, SlruScanDirCbRemoveMembers, &range); + elog(DEBUG1, "performing multixact truncation: " + "offsets [%u, %u), offset segments [%x, %x), " + "members [%u, %u), member segments [%x, %x)", + oldestMulti, newOldestMulti, + MultiXactIdToOffsetSegment(oldestMulti), + MultiXactIdToOffsetSegment(newOldestMulti), + oldestOffset, newOldestOffset, + MXOffsetToMemberSegment(oldestOffset), + MXOffsetToMemberSegment(newOldestOffset)); /* - * Now we can truncate MultiXactOffset. We step back one multixact to - * avoid passing a cutoff page that hasn't been created yet in the rare - * case that oldestMXact would be the first item on a page and oldestMXact - * == nextMXact. In that case, if we didn't subtract one, we'd trigger - * SimpleLruTruncate's wraparound detection. + * Do truncation, and the WAL logging of the truncation, in a critical + * section. That way offsets/members cannot get out of sync anymore, i.e. + * once consistent the newOldestMulti will always exist in members, even if + * we crashed in the wrong moment. */ - SimpleLruTruncate(MultiXactOffsetCtl, - MultiXactIdToOffsetPage(PreviousMultiXactId(oldestMXact))); + START_CRIT_SECTION(); /* - * Now, and only now, we can advance the stop point for multixact members. - * If we did it any sooner, the segments we deleted above might already - * have been overwritten with new members. That would be bad. + * Prevent checkpoints from being scheduled concurrently. This is critical + * because otherwise a truncation record might not be replayed after a + * crash/basebackup, even though the state of the data directory would + * require it. It's not possible (startup process doesn't have a PGXACT + * entry), and not needed, to do this during recovery, when performing an + * old-style truncation, though. There the entire scheduling depends on + * the replayed WAL records which be the same after a possible crash. + */ + if (!in_recovery) + { + Assert(!MyPgXact->delayChkpt); + MyPgXact->delayChkpt = true; + } + + /* WAL log truncation */ + if (!in_recovery) + WriteMTruncateXlogRec(newOldestMultiDB, + oldestMulti, newOldestMulti, + oldestOffset, newOldestOffset); + + /* + * Update in-memory limits before performing the truncation, while inside + * the critical section: Have to do it before truncation, to prevent + * concurrent lookups of those values. Has to be inside the critical + * section as otherwise a future call to this function would error out, + * while looking up the oldest member in offsets, if our caller crashes + * before updating the limits. */ - DetermineSafeOldestOffset(oldestMXact); + LWLockAcquire(MultiXactGenLock, LW_EXCLUSIVE); + MultiXactState->oldestMultiXactId = newOldestMulti; + MultiXactState->oldestMultiXactDB = newOldestMultiDB; + LWLockRelease(MultiXactGenLock); + + /* First truncate members */ + PerformMembersTruncation(oldestOffset, newOldestOffset); + + /* Then offsets */ + PerformOffsetsTruncation(oldestMulti, newOldestMulti); + + if (!in_recovery) + MyPgXact->delayChkpt = false; + + END_CRIT_SECTION(); + LWLockRelease(MultiXactTruncationLock); } /* @@ -3174,6 +3218,34 @@ WriteMZeroPageXlogRec(int pageno, uint8 info) } /* + * Write a TRUNCATE xlog record + * + * We must flush the xlog record to disk before returning --- see notes in + * TruncateCLOG(). + */ +static void +WriteMTruncateXlogRec(Oid oldestMultiDB, + MultiXactId startTruncOff, MultiXactId endTruncOff, + MultiXactOffset startTruncMemb, MultiXactOffset endTruncMemb) +{ + XLogRecPtr recptr; + xl_multixact_truncate xlrec; + + xlrec.oldestMultiDB = oldestMultiDB; + + xlrec.startTruncOff = startTruncOff; + xlrec.endTruncOff = endTruncOff; + + xlrec.startTruncMemb = startTruncMemb; + xlrec.endTruncMemb = endTruncMemb; + + XLogBeginInsert(); + XLogRegisterData((char *) (&xlrec), SizeOfMultiXactTruncate); + recptr = XLogInsert(RM_MULTIXACT_ID, XLOG_MULTIXACT_TRUNCATE_ID); + XLogFlush(recptr); +} + +/* * MULTIXACT resource manager's routines */ void @@ -3255,6 +3327,49 @@ multixact_redo(XLogReaderState *record) LWLockRelease(XidGenLock); } } + else if (info == XLOG_MULTIXACT_TRUNCATE_ID) + { + xl_multixact_truncate xlrec; + int pageno; + + memcpy(&xlrec, XLogRecGetData(record), + SizeOfMultiXactTruncate); + + elog(DEBUG1, "replaying multixact truncation: " + "offsets [%u, %u), offset segments [%x, %x), " + "members [%u, %u), member segments [%x, %x)", + xlrec.startTruncOff, xlrec.endTruncOff, + MultiXactIdToOffsetSegment(xlrec.startTruncOff), + MultiXactIdToOffsetSegment(xlrec.endTruncOff), + xlrec.startTruncMemb, xlrec.endTruncMemb, + MXOffsetToMemberSegment(xlrec.startTruncMemb), + MXOffsetToMemberSegment(xlrec.endTruncMemb)); + + /* should not be required, but more than cheap enough */ + LWLockAcquire(MultiXactTruncationLock, LW_EXCLUSIVE); + + /* + * Advance the horizon values, so they're current at the end of + * recovery. + */ + SetMultiXactIdLimit(xlrec.endTruncOff, xlrec.oldestMultiDB); + + PerformMembersTruncation(xlrec.startTruncMemb, xlrec.endTruncMemb); + + /* + * During XLOG replay, latest_page_number isn't necessarily set up + * yet; insert a suitable value to bypass the sanity test in + * SimpleLruTruncate. + */ + pageno = MultiXactIdToOffsetPage(xlrec.endTruncOff); + MultiXactOffsetCtl->shared->latest_page_number = pageno; + PerformOffsetsTruncation(xlrec.startTruncOff, xlrec.endTruncOff); + + LWLockRelease(MultiXactTruncationLock); + + /* only looked at in the startup process, no lock necessary */ + MultiXactState->sawTruncationInCkptCycle = true; + } else elog(PANIC, "multixact_redo: unknown op code %u", info); } diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c index 5fcea11..90c7cf5 100644 --- a/src/backend/access/transam/slru.c +++ b/src/backend/access/transam/slru.c @@ -134,6 +134,7 @@ static int SlruSelectLRUPage(SlruCtl ctl, int pageno); static bool SlruScanDirCbDeleteCutoff(SlruCtl ctl, char *filename, int segpage, void *data); +static void SlruInternalDeleteSegment(SlruCtl ctl, char *filename); /* * Initialization of shared memory @@ -1075,7 +1076,7 @@ SlruSelectLRUPage(SlruCtl ctl, int pageno) * Flush dirty pages to disk during checkpoint or database shutdown */ void -SimpleLruFlush(SlruCtl ctl, bool checkpoint) +SimpleLruFlush(SlruCtl ctl, bool allow_redirtied) { SlruShared shared = ctl->shared; SlruFlushData fdata; @@ -1096,11 +1097,11 @@ SimpleLruFlush(SlruCtl ctl, bool checkpoint) SlruInternalWritePage(ctl, slotno, &fdata); /* - * When called during a checkpoint, we cannot assert that the slot is - * clean now, since another process might have re-dirtied it already. - * That's okay. + * In some places (e.g. checkpoints), we cannot assert that the slot + * is clean now, since another process might have re-dirtied it + * already. That's okay. */ - Assert(checkpoint || + Assert(allow_redirtied || shared->page_status[slotno] == SLRU_PAGE_EMPTY || (shared->page_status[slotno] == SLRU_PAGE_VALID && !shared->page_dirty[slotno])); @@ -1210,8 +1211,14 @@ restart:; (void) SlruScanDirectory(ctl, SlruScanDirCbDeleteCutoff, &cutoffPage); } -void -SlruDeleteSegment(SlruCtl ctl, char *filename) +/* + * Delete an individual SLRU segment, identified by the filename. + * + * NB: This does not touch the SLRU buffers themselves, callers have to ensure + * they either can't yet contain anything, or have already been cleaned out. + */ +static void +SlruInternalDeleteSegment(SlruCtl ctl, char *filename) { char path[MAXPGPATH]; @@ -1222,6 +1229,64 @@ SlruDeleteSegment(SlruCtl ctl, char *filename) } /* + * Delete an individual SLRU segment, identified by the segment number. + */ +void +SlruDeleteSegment(SlruCtl ctl, int segno) +{ + SlruShared shared = ctl->shared; + int slotno; + char path[MAXPGPATH]; + bool did_write; + + /* Clean out any possibly existing references to the segment. */ + LWLockAcquire(shared->ControlLock, LW_EXCLUSIVE); +restart: + did_write = false; + for (slotno = 0; slotno < shared->num_slots; slotno++) + { + int pagesegno = shared->page_number[slotno] / SLRU_PAGES_PER_SEGMENT; + + if (shared->page_status[slotno] == SLRU_PAGE_EMPTY) + continue; + + /* not the segment we're looking for */ + if (pagesegno != segno) + continue; + + /* If page is clean, just change state to EMPTY (expected case). */ + if (shared->page_status[slotno] == SLRU_PAGE_VALID && + !shared->page_dirty[slotno]) + { + shared->page_status[slotno] = SLRU_PAGE_EMPTY; + continue; + } + + /* Same logic as SimpleLruTruncate() */ + if (shared->page_status[slotno] == SLRU_PAGE_VALID) + SlruInternalWritePage(ctl, slotno, NULL); + else + SimpleLruWaitIO(ctl, slotno); + + did_write = true; + } + + /* + * Be extra careful and re-check. The IO functions release the control + * lock, so new pages could have been read in. + */ + if (did_write) + goto restart; + + snprintf(path, MAXPGPATH, "%s/%04X", ctl->Dir, segno); + ereport(DEBUG2, + (errmsg("removing file \"%s\"", path))); + unlink(path); + + LWLockRelease(shared->ControlLock); +} + +/* * SlruScanDirectory callback * This callback reports true if there's any segment prior to the one * containing the page passed as "data". @@ -1249,7 +1314,7 @@ SlruScanDirCbDeleteCutoff(SlruCtl ctl, char *filename, int segpage, void *data) int cutoffPage = *(int *) data; if (ctl->PagePrecedes(segpage, cutoffPage)) - SlruDeleteSegment(ctl, filename); + SlruInternalDeleteSegment(ctl, filename); return false; /* keep going */ } @@ -1261,7 +1326,7 @@ SlruScanDirCbDeleteCutoff(SlruCtl ctl, char *filename, int segpage, void *data) bool SlruScanDirCbDeleteAll(SlruCtl ctl, char *filename, int segpage, void *data) { - SlruDeleteSegment(ctl, filename); + SlruInternalDeleteSegment(ctl, filename); return false; /* keep going */ } diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index a87f09e..1ac1c05 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -6330,7 +6330,6 @@ StartupXLOG(void) SetMultiXactIdLimit(checkPoint.oldestMulti, checkPoint.oldestMultiDB); SetCommitTsLimit(checkPoint.oldestCommitTs, checkPoint.newestCommitTs); - MultiXactSetSafeTruncate(checkPoint.oldestMulti); XLogCtl->ckptXidEpoch = checkPoint.nextXidEpoch; XLogCtl->ckptXid = checkPoint.nextXid; @@ -6347,10 +6346,8 @@ StartupXLOG(void) StartupReorderBuffer(); /* - * Startup MultiXact. We need to do this early for two reasons: one is - * that we might try to access multixacts when we do tuple freezing, and - * the other is we need its state initialized because we attempt - * truncation during restartpoints. + * Startup MultiXact. We need to do this early to be able to replay + * truncations. */ StartupMultiXact(); @@ -8508,12 +8505,6 @@ CreateCheckPoint(int flags) END_CRIT_SECTION(); /* - * Now that the checkpoint is safely on disk, we can update the point to - * which multixact can be truncated. - */ - MultiXactSetSafeTruncate(checkPoint.oldestMulti); - - /* * Let smgr do post-checkpoint cleanup (eg, deleting old files). */ smgrpostckpt(); @@ -8552,11 +8543,6 @@ CreateCheckPoint(int flags) if (!RecoveryInProgress()) TruncateSUBTRANS(GetOldestXmin(NULL, false)); - /* - * Truncate pg_multixact too. - */ - TruncateMultiXact(); - /* Real work is done, but log and update stats before releasing lock. */ LogCheckpointEnd(false); @@ -8887,21 +8873,6 @@ CreateRestartPoint(int flags) } /* - * Due to a historical accident multixact truncations are not WAL-logged, - * but just performed everytime the mxact horizon is increased. So, unless - * we explicitly execute truncations on a standby it will never clean out - * /pg_multixact which obviously is bad, both because it uses space and - * because we can wrap around into pre-existing data... - * - * We can only do the truncation here, after the UpdateControlFile() - * above, because we've now safely established a restart point. That - * guarantees we will not need to access those multis. - * - * It's probably worth improving this. - */ - TruncateMultiXact(); - - /* * Truncate pg_subtrans if possible. We can throw away all data before * the oldest XMIN of any running transaction. No future transaction will * attempt to reference any pg_subtrans entry older than that (see Asserts @@ -9261,9 +9232,14 @@ xlog_redo(XLogReaderState *record) LWLockRelease(OidGenLock); MultiXactSetNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); + + /* + * NB: This may perform multixact truncation when replaying WAL + * generated by an older primary. + */ + MultiXactAdvanceOldest(checkPoint.oldestMulti, + checkPoint.oldestMultiDB); SetTransactionIdLimit(checkPoint.oldestXid, checkPoint.oldestXidDB); - SetMultiXactIdLimit(checkPoint.oldestMulti, checkPoint.oldestMultiDB); - MultiXactSetSafeTruncate(checkPoint.oldestMulti); /* * If we see a shutdown checkpoint while waiting for an end-of-backup @@ -9353,14 +9329,17 @@ xlog_redo(XLogReaderState *record) LWLockRelease(OidGenLock); MultiXactAdvanceNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); + + /* + * NB: This may perform multixact truncation when replaying WAL + * generated by an older primary. + */ + MultiXactAdvanceOldest(checkPoint.oldestMulti, + checkPoint.oldestMultiDB); if (TransactionIdPrecedes(ShmemVariableCache->oldestXid, checkPoint.oldestXid)) SetTransactionIdLimit(checkPoint.oldestXid, checkPoint.oldestXidDB); - MultiXactAdvanceOldest(checkPoint.oldestMulti, - checkPoint.oldestMultiDB); - MultiXactSetSafeTruncate(checkPoint.oldestMulti); - /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ ControlFile->checkPointCopy.nextXidEpoch = checkPoint.nextXidEpoch; ControlFile->checkPointCopy.nextXid = checkPoint.nextXid; diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index 85b0483..698bb35 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -1137,11 +1137,11 @@ vac_truncate_clog(TransactionId frozenXID, return; /* - * Truncate CLOG and CommitTs to the oldest computed value. Note we don't - * truncate multixacts; that will be done by the next checkpoint. + * Truncate CLOG, multixact and CommitTs to the oldest computed value. */ TruncateCLOG(frozenXID); TruncateCommitTs(frozenXID, true); + TruncateMultiXact(minMulti, minmulti_datoid, false); /* * Update the wrap limit for GetNewTransactionId and creation of new diff --git a/src/backend/storage/lmgr/lwlocknames.txt b/src/backend/storage/lmgr/lwlocknames.txt index 96bbfe8..c557cb6 100644 --- a/src/backend/storage/lmgr/lwlocknames.txt +++ b/src/backend/storage/lmgr/lwlocknames.txt @@ -45,3 +45,4 @@ ReplicationSlotControlLock 37 CommitTsControlLock 38 CommitTsLock 39 ReplicationOriginLock 40 +MultiXactTruncationLock 41 diff --git a/src/include/access/multixact.h b/src/include/access/multixact.h index 6213f8a..47ef38d 100644 --- a/src/include/access/multixact.h +++ b/src/include/access/multixact.h @@ -71,6 +71,7 @@ typedef struct MultiXactMember #define XLOG_MULTIXACT_ZERO_OFF_PAGE 0x00 #define XLOG_MULTIXACT_ZERO_MEM_PAGE 0x10 #define XLOG_MULTIXACT_CREATE_ID 0x20 +#define XLOG_MULTIXACT_TRUNCATE_ID 0x30 typedef struct xl_multixact_create { @@ -82,6 +83,21 @@ typedef struct xl_multixact_create #define SizeOfMultiXactCreate (offsetof(xl_multixact_create, members)) +typedef struct xl_multixact_truncate +{ + Oid oldestMultiDB; + + /* to-be-truncated range of multixact offsets */ + MultiXactId startTruncOff; /* just for completeness' sake */ + MultiXactId endTruncOff; + + /* to-be-truncated range of multixact members */ + MultiXactOffset startTruncMemb; + MultiXactOffset endTruncMemb; +} xl_multixact_truncate; + +#define SizeOfMultiXactTruncate (sizeof(xl_multixact_truncate)) + extern MultiXactId MultiXactIdCreate(TransactionId xid1, MultiXactStatus status1, TransactionId xid2, @@ -120,13 +136,12 @@ extern void MultiXactGetCheckptMulti(bool is_shutdown, Oid *oldestMultiDB); extern void CheckPointMultiXact(void); extern MultiXactId GetOldestMultiXactId(void); -extern void TruncateMultiXact(void); +extern void TruncateMultiXact(MultiXactId oldestMulti, Oid oldestMultiDB, bool in_recovery); extern void MultiXactSetNextMXact(MultiXactId nextMulti, MultiXactOffset nextMultiOffset); extern void MultiXactAdvanceNextMXact(MultiXactId minMulti, MultiXactOffset minMultiOffset); extern void MultiXactAdvanceOldest(MultiXactId oldestMulti, Oid oldestMultiDB); -extern void MultiXactSetSafeTruncate(MultiXactId safeTruncateMulti); extern int MultiXactMemberFreezeThreshold(void); extern void multixact_twophase_recover(TransactionId xid, uint16 info, diff --git a/src/include/access/slru.h b/src/include/access/slru.h index 9c7f019..f60e75b 100644 --- a/src/include/access/slru.h +++ b/src/include/access/slru.h @@ -143,14 +143,14 @@ extern int SimpleLruReadPage(SlruCtl ctl, int pageno, bool write_ok, extern int SimpleLruReadPage_ReadOnly(SlruCtl ctl, int pageno, TransactionId xid); extern void SimpleLruWritePage(SlruCtl ctl, int slotno); -extern void SimpleLruFlush(SlruCtl ctl, bool checkpoint); +extern void SimpleLruFlush(SlruCtl ctl, bool allow_redirtied); extern void SimpleLruTruncate(SlruCtl ctl, int cutoffPage); extern bool SimpleLruDoesPhysicalPageExist(SlruCtl ctl, int pageno); typedef bool (*SlruScanCallback) (SlruCtl ctl, char *filename, int segpage, void *data); extern bool SlruScanDirectory(SlruCtl ctl, SlruScanCallback callback, void *data); -extern void SlruDeleteSegment(SlruCtl ctl, char *filename); +extern void SlruDeleteSegment(SlruCtl ctl, int segno); /* SlruScanDirectory public callbacks */ extern bool SlruScanDirCbReportPresence(SlruCtl ctl, char *filename, diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index a037f81..0e149ea 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2750,6 +2750,7 @@ xl_invalid_page xl_invalid_page_key xl_multi_insert_tuple xl_multixact_create +xl_multixact_truncate xl_parameter_change xl_relmap_update xl_replorigin_drop -- 2.5.0.400.gff86faf