From: Alvaro Herrera Date: Fri, 20 Dec 2013 15:37:30 +0000 (-0300) Subject: Avoid useless palloc during transaction commit X-Git-Tag: REL9_3_3~93 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=fd995b3f4fe52ecd45d06f8cb8b9d217298df917;p=postgresql Avoid useless palloc during transaction commit We can allocate the initial relations-to-drop array when first needed, instead of at function entry; this avoids allocating it when the function is not going to do anything, which is most of the time. Backpatch to 9.3, where this behavior was introduced by commit 279628a0a7cf5. There's more that could be done here, such as possible reworking of the code to avoid having to palloc anything, but that doesn't sound as backpatchable as this relatively minor change. Per complaint from Noah Misch in 20131031145234.GA621493@tornado.leadboat.com --- diff --git a/src/backend/catalog/storage.c b/src/backend/catalog/storage.c index 971a149d59..892f1636a9 100644 --- a/src/backend/catalog/storage.c +++ b/src/backend/catalog/storage.c @@ -314,8 +314,8 @@ smgrDoPendingDeletes(bool isCommit) PendingRelDelete *next; int nrels = 0, i = 0, - maxrels = 8; - SMgrRelation *srels = palloc(maxrels * sizeof(SMgrRelation)); + maxrels = 0; + SMgrRelation *srels = NULL; prev = NULL; for (pending = pendingDeletes; pending != NULL; pending = next) @@ -340,8 +340,13 @@ smgrDoPendingDeletes(bool isCommit) srel = smgropen(pending->relnode, pending->backend); - /* extend the array if needed (double the size) */ - if (maxrels <= nrels) + /* allocate the initial array, or extend it, if needed */ + if (maxrels == 0) + { + maxrels = 8; + srels = palloc(sizeof(SMgrRelation) * maxrels ); + } + else if (maxrels <= nrels) { maxrels *= 2; srels = repalloc(srels, sizeof(SMgrRelation) * maxrels); @@ -361,10 +366,9 @@ smgrDoPendingDeletes(bool isCommit) for (i = 0; i < nrels; i++) smgrclose(srels[i]); - } - - pfree(srels); + pfree(srels); + } } /*