From a2822fb9337a21f98ac4ce850bb4145acf47ca27 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 7 Oct 2011 20:13:02 -0400 Subject: Support index-only scans using the visibility map to avoid heap fetches. When a btree index contains all columns required by the query, and the visibility map shows that all tuples on a target heap page are visible-to-all, we don't need to fetch that heap page. This patch depends on the previous patches that made the visibility map reliable. There's a fair amount left to do here, notably trying to figure out a less chintzy way of estimating the cost of an index-only scan, but the core functionality seems ready to commit. Robert Haas and Ibrar Ahmed, with some previous work by Heikki Linnakangas. --- src/backend/utils/misc/postgresql.conf.sample | 1 + 1 file changed, 1 insertion(+) (limited to 'src/backend/utils/misc/postgresql.conf.sample') diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 5bb7e7117bc..1d8bd3dd235 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -243,6 +243,7 @@ #enable_hashagg = on #enable_hashjoin = on #enable_indexscan = on +#enable_indexonlyscan = on #enable_material = on #enable_mergejoin = on #enable_nestloop = on -- cgit v1.2.3