Planner Costing Errors
TOAST access cost doesn't affect estimates
http://archives.postgresql.org/message-id/4ED68EEC.9030906@krogh.cc
Plan change causes volume of data to exceed server memory
http://archives.postgresql.org/message-id/4E04BB75.4070403@riskcontrollimited.com
http://archives.postgresql.org/message-id/4E09A389.80604@riskcontrollimited.com
Hash join sometimes hashes the wrong table
http://www.postgresql.org/message-id/D2BFB0D2-5EB3-4921-8B0B-C44402C9C03B@skiline.cc