From b719c0b556a6823c9b48c0f4042aaf77a8d5f69e Mon Sep 17 00:00:00 2001 From: Craig Ringer Date: Wed, 22 Mar 2017 12:11:17 +0800 Subject: [PATCH 1/2] Allow GetOldestXmin to ignore replication slot xmin For walsender to report replication slots' catalog_xmin separately, it's necessary to be able to ask GetOldestXmin to ignore replication slots. --- contrib/pg_visibility/pg_visibility.c | 4 ++-- contrib/pgstattuple/pgstatapprox.c | 2 +- src/backend/access/transam/xlog.c | 4 ++-- src/backend/catalog/index.c | 2 +- src/backend/commands/analyze.c | 2 +- src/backend/commands/vacuum.c | 4 ++-- src/backend/replication/walreceiver.c | 2 +- src/backend/storage/ipc/procarray.c | 36 +++++++++++++++++++++++++++-------- src/include/storage/procarray.h | 2 +- 9 files changed, 39 insertions(+), 19 deletions(-) diff --git a/contrib/pg_visibility/pg_visibility.c b/contrib/pg_visibility/pg_visibility.c index d0f7618..6261e68 100644 --- a/contrib/pg_visibility/pg_visibility.c +++ b/contrib/pg_visibility/pg_visibility.c @@ -557,7 +557,7 @@ collect_corrupt_items(Oid relid, bool all_visible, bool all_frozen) if (all_visible) { /* Don't pass rel; that will fail in recovery. */ - OldestXmin = GetOldestXmin(NULL, true); + OldestXmin = GetOldestXmin(NULL, true, false); } rel = relation_open(relid, AccessShareLock); @@ -674,7 +674,7 @@ collect_corrupt_items(Oid relid, bool all_visible, bool all_frozen) * a buffer lock. And this shouldn't happen often, so it's * worth being careful so as to avoid false positives. */ - RecomputedOldestXmin = GetOldestXmin(NULL, true); + RecomputedOldestXmin = GetOldestXmin(NULL, true, false); if (!TransactionIdPrecedes(OldestXmin, RecomputedOldestXmin)) record_corrupt_item(items, &tuple.t_self); diff --git a/contrib/pgstattuple/pgstatapprox.c b/contrib/pgstattuple/pgstatapprox.c index 8db1e20..743cbee 100644 --- a/contrib/pgstattuple/pgstatapprox.c +++ b/contrib/pgstattuple/pgstatapprox.c @@ -70,7 +70,7 @@ statapprox_heap(Relation rel, output_type *stat) TransactionId OldestXmin; uint64 misc_count = 0; - OldestXmin = GetOldestXmin(rel, true); + OldestXmin = GetOldestXmin(rel, true, false); bstrategy = GetAccessStrategy(BAS_BULKREAD); nblocks = RelationGetNumberOfBlocks(rel); diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 9480377..c2b4f2c 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -8895,7 +8895,7 @@ CreateCheckPoint(int flags) * StartupSUBTRANS hasn't been called yet. */ if (!RecoveryInProgress()) - TruncateSUBTRANS(GetOldestXmin(NULL, false)); + TruncateSUBTRANS(GetOldestXmin(NULL, false, false)); /* Real work is done, but log and update stats before releasing lock. */ LogCheckpointEnd(false); @@ -9258,7 +9258,7 @@ CreateRestartPoint(int flags) * this because StartupSUBTRANS hasn't been called yet. */ if (EnableHotStandby) - TruncateSUBTRANS(GetOldestXmin(NULL, false)); + TruncateSUBTRANS(GetOldestXmin(NULL, false, false)); /* Real work is done, but log and update before releasing lock. */ LogCheckpointEnd(true); diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8d42a34..7ce7c8f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -2270,7 +2270,7 @@ IndexBuildHeapRangeScan(Relation heapRelation, { snapshot = SnapshotAny; /* okay to ignore lazy VACUUMs here */ - OldestXmin = GetOldestXmin(heapRelation, true); + OldestXmin = GetOldestXmin(heapRelation, true, false); } scan = heap_beginscan_strat(heapRelation, /* relation */ diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c index b91df98..0f166a0 100644 --- a/src/backend/commands/analyze.c +++ b/src/backend/commands/analyze.c @@ -1000,7 +1000,7 @@ acquire_sample_rows(Relation onerel, int elevel, totalblocks = RelationGetNumberOfBlocks(onerel); /* Need a cutoff xmin for HeapTupleSatisfiesVacuum */ - OldestXmin = GetOldestXmin(onerel, true); + OldestXmin = GetOldestXmin(onerel, true, false); /* Prepare for sampling block numbers */ BlockSampler_Init(&bs, totalblocks, targrows, random()); diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index ff633fa..bdc7e16 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -527,7 +527,7 @@ vacuum_set_xid_limits(Relation rel, * always an independent transaction. */ *oldestXmin = - TransactionIdLimitedForOldSnapshots(GetOldestXmin(rel, true), rel); + TransactionIdLimitedForOldSnapshots(GetOldestXmin(rel, true, false), rel); Assert(TransactionIdIsNormal(*oldestXmin)); @@ -939,7 +939,7 @@ vac_update_datfrozenxid(void) * committed pg_class entries for new tables; see AddNewRelationTuple(). * So we cannot produce a wrong minimum by starting with this. */ - newFrozenXid = GetOldestXmin(NULL, true); + newFrozenXid = GetOldestXmin(NULL, true, false); /* * Similarly, initialize the MultiXact "min" with the value that would be diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c index 18d9d7e..b1ab8e0 100644 --- a/src/backend/replication/walreceiver.c +++ b/src/backend/replication/walreceiver.c @@ -1221,7 +1221,7 @@ XLogWalRcvSendHSFeedback(bool immed) * everything else has been checked. */ if (hot_standby_feedback) - xmin = GetOldestXmin(NULL, false); + xmin = GetOldestXmin(NULL, false, false); else xmin = InvalidTransactionId; diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index 0f8f435..63083c9 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -1292,17 +1292,22 @@ TransactionIdIsActive(TransactionId xid) * process can set its xmin based on transactions that are no longer running * in the master but are still being replayed on the standby, thus possibly * making the GetOldestXmin reading go backwards. In this case there is a - * possibility that we lose data that the standby would like to have, but - * there is little we can do about that --- data is only protected if the - * walsender runs continuously while queries are executed on the standby. - * (The Hot Standby code deals with such cases by failing standby queries - * that needed to access already-removed data, so there's no integrity bug.) + * possibility that we lose data that the standby would like to have + * unless the standby uses a replication slot to make its xmin persistent + * even when it isn't connected. The Hot Standby code deals with such cases by + * failing standby queries that needed to access already-removed data, so + * there's no integrity bug. + * * The return value is also adjusted with vacuum_defer_cleanup_age, so * increasing that setting on the fly is another easy way to make * GetOldestXmin() move backwards, with no consequences for data integrity. + * + * The caller may request that replication slots' catalog_xmin values be + * disregarded when calculating the global xmin. The caller must account + * for catalog_xmin separately. */ TransactionId -GetOldestXmin(Relation rel, bool ignoreVacuum) +GetOldestXmin(Relation rel, bool ignoreVacuum, bool ignoreCatalogXmin) { ProcArrayStruct *arrayP = procArray; TransactionId result; @@ -1376,7 +1381,9 @@ GetOldestXmin(Relation rel, bool ignoreVacuum) } } - /* fetch into volatile var while ProcArrayLock is held */ + /* + * Fetch slot xmins into volatile var while ProcArrayLock is held. + */ replication_slot_xmin = procArray->replication_slot_xmin; replication_slot_catalog_xmin = procArray->replication_slot_catalog_xmin; @@ -1430,11 +1437,24 @@ GetOldestXmin(Relation rel, bool ignoreVacuum) /* * After locks have been released and defer_cleanup_age has been applied, * check whether we need to back up further to make logical decoding + * safe. We need to do so if we're computing the global limit (rel = + * NULL) or if the passed relation is a catalog relation of some kind, + * unless the caller asked us not to. + */ + if (!ignoreCatalogXmin && + (rel == NULL || RelationIsAccessibleInLogicalDecoding(rel)) && + TransactionIdIsValid(replication_slot_catalog_xmin) && + NormalTransactionIdPrecedes(replication_slot_catalog_xmin, result)) + result = replication_slot_catalog_xmin; + + /* + * After locks have been released and defer_cleanup_age has been applied, + * check whether we need to back up further to make logical decoding * possible. We need to do so if we're computing the global limit (rel = * NULL) or if the passed relation is a catalog relation of some kind. */ if ((rel == NULL || - RelationIsAccessibleInLogicalDecoding(rel)) && + RelationIsAccessibleInLogicalDecoding(rel)) && TransactionIdIsValid(replication_slot_catalog_xmin) && NormalTransactionIdPrecedes(replication_slot_catalog_xmin, result)) result = replication_slot_catalog_xmin; diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h index 9d5a13e..21d022f 100644 --- a/src/include/storage/procarray.h +++ b/src/include/storage/procarray.h @@ -53,7 +53,7 @@ extern RunningTransactions GetRunningTransactionData(void); extern bool TransactionIdIsInProgress(TransactionId xid); extern bool TransactionIdIsActive(TransactionId xid); -extern TransactionId GetOldestXmin(Relation rel, bool ignoreVacuum); +extern TransactionId GetOldestXmin(Relation rel, bool ignoreVacuum, bool ignoreCatalogXmin); extern TransactionId GetOldestActiveTransactionId(void); extern TransactionId GetOldestSafeDecodingTransactionId(void); -- 2.5.5