diff options
| 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/commands/cluster.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/commands/cluster.c')
| -rw-r--r-- | src/backend/commands/cluster.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 8200d2095a7..edec44d2c3d 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1205,6 +1205,7 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, { int4 swap_pages; float4 swap_tuples; + int4 swap_allvisible; swap_pages = relform1->relpages; relform1->relpages = relform2->relpages; @@ -1213,6 +1214,10 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, swap_tuples = relform1->reltuples; relform1->reltuples = relform2->reltuples; relform2->reltuples = swap_tuples; + + swap_allvisible = relform1->relallvisible; + relform1->relallvisible = relform2->relallvisible; + relform2->relallvisible = swap_allvisible; } /* |