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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 21:21:56 -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% 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 ------