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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2011-10-07 20:13:02 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2011-10-07 20:14:13 -0400 |
| commit | a2822fb9337a21f98ac4ce850bb4145acf47ca27 (patch) | |
| tree | c239fe9a32ff0225e906711a76348cee1567f0d8 /src/backend/commands/explain.c | |
| parent | caa1054df8408b165e5f66ff25c87b6dd0a0a1e7 (diff) | |
| download | postgresql-a2822fb9337a21f98ac4ce850bb4145acf47ca27.tar.gz postgresql-a2822fb9337a21f98ac4ce850bb4145acf47ca27.zip | |
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.
Diffstat (limited to 'src/backend/commands/explain.c')
| -rw-r--r-- | src/backend/commands/explain.c | 5 |
1 files changed, 4 insertions, 1 deletions
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"; |