I have always been frustrated by the wildly erratic performance of our postgresql 8 server. We run aprogram that does heavy data importing via a heuristics-based import program. Sometime records being imported would just fly by, sometimes they would crawl. The import program imports records from a flat table and uses heuristics to normalise and dedupe. This is done via a sequence of updates and inserts bracketed by a start-end transaction. At a certain checkpoint representing about 1,000,000 rows read and imported, I ran a vacuum/analyze on all of the tables in the target schema. To my horror, performance reduced to less than TEN percent of what it was befor the vacuum/analyze. I thought that turning autovacuum off and doing my own vacuuming would improve performance, but it seems to be killing it. I have since turned autovacuum on and am tearing my hair out wathcing the imported records crawl by. I have tried vacuuming the entire DB as well as rebuilding indexes. Nothing. Any ideas what could have happened? What is the right thing to do? Carlo
