Index: src/backend/access/heap/README.HOT
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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
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*** 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
  ------