We are currently running postgres 8.2 and are evaluating the upgrade to 8.3. Some of our tests are indicating that postgresql 8.3 is actually degrading the performance of some of our queries by a factor of 10 or more. The queries in question are selects that are heavy on joins (~10 tables) with a lot of timestamp-based conditions in where clauses. The tables and queries are tuned, that is, there is no issue with the table structure, or missing indexes. This is a side-by-side query performance measurement between 8.2 and 8.3 with an identical dataset and schema.
8.2.12 8.3.3 Time (ms) Time (ms) 1st 2nd 1st 2nd time time time time
Query 1 759 130 3294 1758
attached you will find the explain analyze for this query. Any insight into this issue would be very appreciated. Thanks.