From 614e0729a814091b3c73f9a02c3470a03b83248a Mon Sep 17 00:00:00 2001 From: Fujii Masao Date: Thu, 5 Jul 2018 02:21:15 +0900 Subject: [PATCH] Improve the performance of relation deletes during recovery. When multiple relations are deleted at the same transaction, the files of those relations are deleted by one call to smgrdounlinkall(), which leads to scan whole shared_buffers only one time. OTOH, previously, during recovery, smgrdounlink() (not smgrdounlinkall()) was called for each file to delete, which led to scan shared_buffers multiple times. Obviously this could cause to increase the WAL replay time very much especially when shared_buffers was huge. To alleviate this situation, this commit changes the recovery so that it also calls smgrdounlinkall() only one time to delete multiple relation files. This is just fix for oversight of commit 279628a0a7, not new feature. So, per discussion on pgsql-hackers, we concluded to backpatch this to all supported versions. Author: Fujii Masao Reviewed-by: Michael Paquier, Andres Freund, Thomas Munro, Kyotaro Horiguchi, Takayuki Tsunakawa Discussion: https://postgr.es/m/CAHGQGwHVQkdfDqtvGVkty+19cQakAydXn1etGND3X0PHbZ3+6w@mail.gmail.com --- src/backend/access/transam/twophase.c | 9 ++----- src/backend/access/transam/xact.c | 25 +++--------------- src/backend/storage/smgr/md.c | 38 +++++++++++++++++++++++++++ src/include/storage/smgr.h | 1 + 4 files changed, 44 insertions(+), 29 deletions(-) diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c index 10d615068c..faf590b770 100644 --- a/src/backend/access/transam/twophase.c +++ b/src/backend/access/transam/twophase.c @@ -1373,7 +1373,6 @@ FinishPreparedTransaction(const char *gid, bool isCommit) RelFileNode *delrels; int ndelrels; SharedInvalidationMessage *invalmsgs; - int i; /* * Validate the GID, and lock the GXACT to ensure that two backends do not @@ -1463,13 +1462,9 @@ FinishPreparedTransaction(const char *gid, bool isCommit) delrels = abortrels; ndelrels = hdr->nabortrels; } - for (i = 0; i < ndelrels; i++) - { - SMgrRelation srel = smgropen(delrels[i], InvalidBackendId); - smgrdounlink(srel, false); - smgrclose(srel); - } + /* Make sure files supposed to be dropped are dropped */ + DropRelationFiles(delrels, ndelrels, false); /* * Handle cache invalidation messages. diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index f4ddd2604f..d3632c25ca 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -5322,7 +5322,6 @@ xact_redo_commit(xl_xact_parsed_commit *parsed, RepOriginId origin_id) { TransactionId max_xid; - int i; TimestampTz commit_time; max_xid = TransactionIdLatest(xid, parsed->nsubxacts, parsed->subxacts); @@ -5439,16 +5438,8 @@ xact_redo_commit(xl_xact_parsed_commit *parsed, */ XLogFlush(lsn); - for (i = 0; i < parsed->nrels; i++) - { - SMgrRelation srel = smgropen(parsed->xnodes[i], InvalidBackendId); - ForkNumber fork; - - for (fork = 0; fork <= MAX_FORKNUM; fork++) - XLogDropRelation(parsed->xnodes[i], fork); - smgrdounlink(srel, true); - smgrclose(srel); - } + /* Make sure files supposed to be dropped are dropped */ + DropRelationFiles(parsed->xnodes, parsed->nrels, true); } /* @@ -5480,7 +5471,6 @@ xact_redo_commit(xl_xact_parsed_commit *parsed, static void xact_redo_abort(xl_xact_parsed_abort *parsed, TransactionId xid) { - int i; TransactionId max_xid; /* @@ -5542,16 +5532,7 @@ xact_redo_abort(xl_xact_parsed_abort *parsed, TransactionId xid) } /* Make sure files supposed to be dropped are dropped */ - for (i = 0; i < parsed->nrels; i++) - { - SMgrRelation srel = smgropen(parsed->xnodes[i], InvalidBackendId); - ForkNumber fork; - - for (fork = 0; fork <= MAX_FORKNUM; fork++) - XLogDropRelation(parsed->xnodes[i], fork); - smgrdounlink(srel, true); - smgrclose(srel); - } + DropRelationFiles(parsed->xnodes, parsed->nrels, true); } void diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c index b36198ed4a..849055b191 100644 --- a/src/backend/storage/smgr/md.c +++ b/src/backend/storage/smgr/md.c @@ -26,6 +26,7 @@ #include #include "miscadmin.h" +#include "access/xlogutils.h" #include "access/xlog.h" #include "catalog/catalog.h" #include "portability/instr_time.h" @@ -1641,6 +1642,43 @@ ForgetDatabaseFsyncRequests(Oid dbid) } } +/* + * DropRelationFiles -- drop files of all given relations + */ +void +DropRelationFiles(RelFileNode *delrels, int ndelrels, bool isRedo) +{ + SMgrRelation *srels; + int i; + + srels = palloc(sizeof(SMgrRelation) * ndelrels); + for (i = 0; i < ndelrels; i++) + { + SMgrRelation srel = smgropen(delrels[i], InvalidBackendId); + + if (isRedo) + { + ForkNumber fork; + + for (fork = 0; fork <= MAX_FORKNUM; fork++) + XLogDropRelation(delrels[i], fork); + } + srels[i] = srel; + } + + smgrdounlinkall(srels, ndelrels, isRedo); + + /* + * Call smgrclose() in reverse order as when smgropen() is called. + * This trick enables remove_from_unowned_list() in smgrclose() + * to search the SMgrRelation from the unowned list, + * with O(1) performance. + */ + for (i = ndelrels - 1; i >= 0; i--) + smgrclose(srels[i]); + pfree(srels); +} + /* * _fdvec_alloc() -- Make a MdfdVec object. diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h index 69a624fe23..dfb7e98e93 100644 --- a/src/include/storage/smgr.h +++ b/src/include/storage/smgr.h @@ -135,6 +135,7 @@ extern void RememberFsyncRequest(RelFileNode rnode, ForkNumber forknum, BlockNumber segno); extern void ForgetRelationFsyncRequests(RelFileNode rnode, ForkNumber forknum); extern void ForgetDatabaseFsyncRequests(Oid dbid); +extern void DropRelationFiles(RelFileNode *delrels, int ndelrels, bool isRedo); /* smgrtype.c */ extern Datum smgrout(PG_FUNCTION_ARGS); -- 2.50.1