> > > > I remember postgresql 8.4 is replanning prepared statements when > > > > statistics change occur, but I didn't find it in the release notes. > > > > It is just saying "Invalidate cached plans when referenced schemas, > > > > functions, operators, or operator classes are modified". Does PG > > > > replans prepared statements from time to time if underlying data > > > > statistics change? > > > > > > I don't think so, though I may be wrong. The change you refer to > > > replans such things when the actual objects change, such as when you > > > remove a column or something that would make the plan fail to execute. > > > > Ok, so i should be aware of this. if the execution plan postgresql is > > caching gets old, i can run into trouble. > > > > So i should close my connections in the pool from time to time to force > > replanning of my prepared statements. > > I'm not sure this is a great idea, but it would depend on your application. > With caching and pooling and such, a prepared statement might live a really > long time, but your database's statistics might take even longer to change > sufficiently to suggest one plan is better than another. Explicitly > replanning sounds like it's probably more work than it's worth, unless you > see specific plan problems. I know close my connections every 5th hour, so a new connection can create new preparedStatements with a new execution plan. I had some situations in the past, where an old plan took so much longer. I think planning a statement doesn't cost so much compared with executing a statement with a wrong plan (like sequence scan instead of using an index) But I remember a post of tom lane who said that prepared statements get replaned since 8.4 if underlying statistics change. But I really can't find it. Maybe I do not remember correctly. kind regards Janning > -- > Joshua Tolley / eggyknap > End Point Corporation > http://www.endpoint.com -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
