Chris Hoover escribió: > Another question. > > When autovacuum sleeps, does it release the lock it has on the table? What do you mean sleep? There are two sleeps: the one caused by cost-based vacuum delay (lasts for some milliseconds, happens every handful of pages vacuumed; no locks released here) and the big sleep that happens after one worker finishes and the next one starts (all locks are released). When one autovac worker is processing a table, no other worker touches it. So if you have a table that's 64 GB, it won't be analyzed until the currently running vacuum finishes. > What we would like to have happen is for vacuum to work for a while, sleep, > and while it is sleeping run an analyze on the table. We need this due to > how quickly our data is changing. Currently we are running analyze every 5 > minutes against the table of question and get a very serious performance hit > when vacuum runs due to the index stats getting out of date. As soon as we > rerun analyze after the vacuum happiness returns. This is worst case for Postgres vacuuming, I think. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc.
