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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/utils/misc/guc.c | |
| parent | caa1054df8408b165e5f66ff25c87b6dd0a0a1e7 (diff) | |
| download | postgresql-a2822fb9337a21f98ac4ce850bb4145acf47ca27.tar.gz | |
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/utils/misc/guc.c')
| -rw-r--r-- | src/backend/utils/misc/guc.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 85fdad8996..106096faee 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -682,6 +682,15 @@ static struct config_bool ConfigureNamesBool[] = NULL, NULL, NULL }, { + {"enable_indexonlyscan", PGC_USERSET, QUERY_TUNING_METHOD, + gettext_noop("Enables the planner's use of index-only-scan plans."), + NULL + }, + &enable_indexonlyscan, + true, + NULL, NULL, NULL + }, + { {"enable_bitmapscan", PGC_USERSET, QUERY_TUNING_METHOD, gettext_noop("Enables the planner's use of bitmap-scan plans."), NULL |