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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2011-10-14 17:23:01 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2011-10-14 17:23:46 -0400 |
| commit | e6858e665731c0f56d3ecc9fbb245c32d24f8ef7 (patch) | |
| tree | 4df2705d53d53b1bbd7a14d7017cb519d82ee227 /src/backend/nodes/outfuncs.c | |
| parent | dea95c7a7beb5ef66ce89269dd0e84d0c26e5523 (diff) | |
| download | postgresql-e6858e665731c0f56d3ecc9fbb245c32d24f8ef7.tar.gz postgresql-e6858e665731c0f56d3ecc9fbb245c32d24f8ef7.zip | |
Measure the number of all-visible pages for use in index-only scan costing.
Add a column pg_class.relallvisible to remember the number of pages that
were all-visible according to the visibility map as of the last VACUUM
(or ANALYZE, or some other operations that update pg_class.relpages).
Use relallvisible/relpages, instead of an arbitrary constant, to estimate
how many heap page fetches can be avoided during an index-only scan.
This is pretty primitive and will no doubt see refinements once we've
acquired more field experience with the index-only scan mechanism, but
it's way better than using a constant.
Note: I had to adjust an underspecified query in the window.sql regression
test, because it was changing answers when the plan changed to use an
index-only scan. Some of the adjacent tests perhaps should be adjusted
as well, but I didn't do that here.
Diffstat (limited to 'src/backend/nodes/outfuncs.c')
| -rw-r--r-- | src/backend/nodes/outfuncs.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c index eba3d6d5797..98a02b27ddf 100644 --- a/src/backend/nodes/outfuncs.c +++ b/src/backend/nodes/outfuncs.c @@ -1743,6 +1743,7 @@ _outRelOptInfo(StringInfo str, RelOptInfo *node) WRITE_NODE_FIELD(indexlist); WRITE_UINT_FIELD(pages); WRITE_FLOAT_FIELD(tuples, "%.0f"); + WRITE_FLOAT_FIELD(allvisfrac, "%.6f"); WRITE_NODE_FIELD(subplan); WRITE_NODE_FIELD(subroot); WRITE_NODE_FIELD(baserestrictinfo); |