diff options
| author | Bruce Momjian | 2010-09-19 17:51:44 +0000 |
|---|---|---|
| committer | Bruce Momjian | 2010-09-19 17:51:44 +0000 |
| commit | cecde97577fafddc6b3aa354b9b77a3a54b063a9 (patch) | |
| tree | 2faed32d5358a712a908e9d1f81acacddba811f5 | |
| parent | f679cfe97b8f34427949a915e4008cc7d1213851 (diff) | |
Update HOT README about when single-page vacuums happen.
| -rw-r--r-- | src/backend/access/heap/README.HOT | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/src/backend/access/heap/README.HOT b/src/backend/access/heap/README.HOT index 2f9162e52d4..d32b7f59abc 100644 --- a/src/backend/access/heap/README.HOT +++ b/src/backend/access/heap/README.HOT @@ -1,4 +1,4 @@ -$PostgreSQL: pgsql/src/backend/access/heap/README.HOT,v 1.6 2010/04/23 23:21:44 rhaas Exp $ +$PostgreSQL: pgsql/src/backend/access/heap/README.HOT,v 1.7 2010/09/19 17:51:44 momjian Exp $ Heap Only Tuples (HOT) ====================== @@ -246,6 +246,12 @@ scans reasonably sized, the maximum number of line pointers per page is arbitrarily capped at MaxHeapTuplesPerPage (the most tuples that could fit without HOT pruning). +Effectively, space reclamation happens during tuple retrieval when the +page is nearly full (<10% free) and a buffer cleanup lock can be +acquired. This means that UPDATE, DELETE, and SELECT can trigger space +reclamation, but often not during INSERT ... VALUES because it does +not retrieve a row. + VACUUM ------ |