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/commands/explain.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'src/backend/commands/explain.c') diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index cd9fc929232..fbcaf6cbe09 100644 --- a/src/backend/commands/explain.c +++ b/src/backend/commands/explain.c @@ -656,7 +656,10 @@ ExplainNode(PlanState *planstate, List *ancestors, pname = sname = "Seq Scan"; break; case T_IndexScan: - pname = sname = "Index Scan"; + if (((IndexScan *) plan)->indexonly) + pname = sname = "Index Only Scan"; + else + pname = sname = "Index Scan"; break; case T_BitmapIndexScan: pname = sname = "Bitmap Index Scan"; -- cgit v1.2.3