From 75a220fc3a4919e4e6fa188515f80082b9dacd09 Mon Sep 17 00:00:00 2001 From: Kirk Jamison Date: Wed, 28 Oct 2020 06:32:01 +0000 Subject: [PATCH v28 4/4] TRUNCATE optimization. --- src/backend/storage/buffer/bufmgr.c | 74 +++++++++++++++++++++++++++++++++++-- src/backend/storage/smgr/smgr.c | 14 +++---- src/include/storage/bufmgr.h | 2 +- 3 files changed, 79 insertions(+), 11 deletions(-) diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 18d8512..e1c1190 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -3121,17 +3121,37 @@ DropRelFileNodeBuffers(SMgrRelation smgr_reln, ForkNumber *forkNum, * -------------------------------------------------------------------- */ void -DropRelFileNodesAllBuffers(RelFileNodeBackend *rnodes, int nnodes) +DropRelFileNodesAllBuffers(SMgrRelation *smgr_reln, int nnodes) { int i, + j, + nforks, n = 0; + SMgrRelation *rels; + RelFileNodeBackend *rnodes; RelFileNode *nodes; + BlockNumber firstDelBlocks[MAX_FORKNUM + 1]; + BlockNumber nblocks; + BlockNumber nBlocksToInvalidate; + ForkNumber forks[MAX_FORKNUM + 1]; + bool accurate; bool use_bsearch; if (nnodes == 0) return; - nodes = palloc(sizeof(RelFileNode) * nnodes); /* non-local relations */ + /* Create an array which contains all relations to be dropped */ + rnodes = palloc(sizeof(RelFileNodeBackend) * nnodes); + for (i = 0; i < nnodes; i++) + { + RelFileNodeBackend rnode = smgr_reln[i]->smgr_rnode; + + rnodes[i] = rnode; + } + + /* non-local relations */ + rels = (SMgrRelation *)palloc(nnodes * sizeof(SMgrRelation)); + nodes = palloc(sizeof(RelFileNode) * nnodes); /* If it's a local relation, it's localbuf.c's problem. */ for (i = 0; i < nnodes; i++) @@ -3142,7 +3162,10 @@ DropRelFileNodesAllBuffers(RelFileNodeBackend *rnodes, int nnodes) DropRelFileNodeAllLocalBuffers(rnodes[i].node); } else + { + rels[n] = smgr_reln[i]; nodes[n++] = rnodes[i].node; + } } /* @@ -3152,10 +3175,54 @@ DropRelFileNodesAllBuffers(RelFileNodeBackend *rnodes, int nnodes) if (n == 0) { pfree(nodes); + pfree(rels); + pfree(rnodes); return; } /* + * Zero the array of blocks because these will all be dropped anyway. + * Get the total number of blocks for a given fork per relation. + * Give up the optimization if the block count of any fork of relation + * cannot be trusted. + */ + memset(firstDelBlocks, 0, sizeof(firstDelBlocks)); + for (i = 0; i < n; i++) + { + nforks = 0; + nBlocksToInvalidate = 0; + + for (j = 0; j <= MAX_FORKNUM; j++) + { + if (!smgrexists(rels[i], j)) + continue; + + /* Get the number of blocks for a relation's fork */ + nblocks = smgrnblocks(rels[i], j, &accurate); + + if (!accurate) + break; + + nBlocksToInvalidate += nblocks; + + forks[nforks++] = j; + } + if (!accurate || j >= MAX_FORKNUM || + nBlocksToInvalidate >= BUF_DROP_FULL_SCAN_THRESHOLD) + { + goto buffer_full_scan; + return; + } + + DropRelFileNodeBuffers(rels[i], forks, nforks, firstDelBlocks); + } + pfree(nodes); + pfree(rels); + pfree(rnodes); + return; + +buffer_full_scan: + /* * For low number of relations to drop just use a simple walk through, to * save the bsearch overhead. The threshold to use is rather a guess than * an exactly determined value, as it depends on many factors (CPU and RAM @@ -3208,8 +3275,9 @@ DropRelFileNodesAllBuffers(RelFileNodeBackend *rnodes, int nnodes) else UnlockBufHdr(bufHdr, buf_state); } - pfree(nodes); + pfree(rels); + pfree(rnodes); } /* --------------------------------------------------------------------- diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c index 6b8528e..fd2cf84 100644 --- a/src/backend/storage/smgr/smgr.c +++ b/src/backend/storage/smgr/smgr.c @@ -392,7 +392,13 @@ smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo) return; /* - * create an array which contains all relations to be dropped, and close + * Get rid of any remaining buffers for the relations. bufmgr will just + * drop them without bothering to write the contents. + */ + DropRelFileNodesAllBuffers(rels, nrels); + + /* + * Create an array which contains all relations to be dropped, and close * each relation's forks at the smgr level while at it */ rnodes = palloc(sizeof(RelFileNodeBackend) * nrels); @@ -409,12 +415,6 @@ smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo) } /* - * Get rid of any remaining buffers for the relations. bufmgr will just - * drop them without bothering to write the contents. - */ - DropRelFileNodesAllBuffers(rnodes, nrels); - - /* * It'd be nice to tell the stats collector to forget them immediately, * too. But we can't because we don't know the OIDs. */ diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h index 056f65e..2e5189b 100644 --- a/src/include/storage/bufmgr.h +++ b/src/include/storage/bufmgr.h @@ -205,7 +205,7 @@ extern void FlushRelationsAllBuffers(struct SMgrRelationData **smgrs, int nrels) extern void FlushDatabaseBuffers(Oid dbid); extern void DropRelFileNodeBuffers(struct SMgrRelationData *smgr_reln, ForkNumber *forkNum, int nforks, BlockNumber *firstDelBlock); -extern void DropRelFileNodesAllBuffers(RelFileNodeBackend *rnodes, int nnodes); +extern void DropRelFileNodesAllBuffers(struct SMgrRelationData **smgr_reln, int nnodes); extern void DropDatabaseBuffers(Oid dbid); #define RelationGetNumberOfBlocks(reln) \ -- 1.8.3.1