I would like to apply the attached patch to README.HOT so clarify when single-page cleanup happens, e.g. not during INSERT.
-- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. +
Index: src/backend/access/heap/README.HOT =================================================================== RCS file: /cvsroot/pgsql/src/backend/access/heap/README.HOT,v retrieving revision 1.6 diff -c -c -r1.6 README.HOT *** src/backend/access/heap/README.HOT 23 Apr 2010 23:21:44 -0000 1.6 --- src/backend/access/heap/README.HOT 17 Sep 2010 19:48:16 -0000 *************** *** 246,251 **** --- 246,257 ---- 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%) and a buffer cleanup lock can be acquired. + This means that UPDATE, DELETE, and SELECT can trigger space + reclamation, while INSERT ... VALUES cannot because it does not retrieve + a row. + VACUUM ------
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