From 80b9e9c4664a020ebd14889046bd8d22a17d1ca6 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sun, 3 Mar 2019 16:57:14 -0500 Subject: Improve performance of index-only scans with many index columns. StoreIndexTuple was a loop over index_getattr, which is O(N^2) if the index columns are variable-width, and the performance impact is already quite visible at ten columns. The obvious move is to replace that with a call to index_deform_tuple ... but that's *also* a loop over index_getattr. Improve it to be essentially a clone of heap_deform_tuple. (There are a few other places that loop over all index columns with index_getattr, and perhaps should be changed likewise, but most of them don't seem performance-critical. Anyway, the rest would mostly only be interested in the index key columns, which there aren't likely to be so many of. Wide index tuples are a new thing with INCLUDE.) Konstantin Knizhnik Discussion: https://postgr.es/m/e06b2d27-04fc-5c0e-bb8c-ecd72aa24959@postgrespro.ru --- src/backend/executor/nodeIndexonlyscan.c | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-) (limited to 'src/backend/executor/nodeIndexonlyscan.c') diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c index 72c04b528f5..26758e77039 100644 --- a/src/backend/executor/nodeIndexonlyscan.c +++ b/src/backend/executor/nodeIndexonlyscan.c @@ -269,23 +269,17 @@ IndexOnlyNext(IndexOnlyScanState *node) static void StoreIndexTuple(TupleTableSlot *slot, IndexTuple itup, TupleDesc itupdesc) { - int nindexatts = itupdesc->natts; - Datum *values = slot->tts_values; - bool *isnull = slot->tts_isnull; - int i; - /* - * Note: we must use the tupdesc supplied by the AM in index_getattr, not - * the slot's tupdesc, in case the latter has different datatypes (this - * happens for btree name_ops in particular). They'd better have the same - * number of columns though, as well as being datatype-compatible which is - * something we can't so easily check. + * Note: we must use the tupdesc supplied by the AM in index_deform_tuple, + * not the slot's tupdesc, in case the latter has different datatypes + * (this happens for btree name_ops in particular). They'd better have + * the same number of columns though, as well as being datatype-compatible + * which is something we can't so easily check. */ - Assert(slot->tts_tupleDescriptor->natts == nindexatts); + Assert(slot->tts_tupleDescriptor->natts == itupdesc->natts); ExecClearTuple(slot); - for (i = 0; i < nindexatts; i++) - values[i] = index_getattr(itup, i + 1, itupdesc, &isnull[i]); + index_deform_tuple(itup, itupdesc, slot->tts_values, slot->tts_isnull); ExecStoreVirtualTuple(slot); } -- cgit v1.2.3