Mahesh Jhala wrote: > Hello All, > > If autovacuum of a large PostgreSQL table is in progress, and I start > a manual vacuum on the table, is there likely to be a conflict > (locking etc.) between the two vacuums? It depends on the autovacuum being for-wraparound or not. If not, then the conflict will be detected within one second and autovacuum will cancel itself, so the regular vacuum would be able to proceed. So there is a one-second period of time during which you would see the manual vacuum as blocked by autovacuum. If autovacuum is for wraparound protection, then it won't cancel itself, and the regular vacuum will just wait until autovacuum is finished. There is a final stage in vacuuming (both auto and regular) during which the table is truncated (the last few empty pages, if any). There's some heuristics to handle that case nowadays which I don't remember very clearly. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
