Alvaro Herrera <alvhe...@alvh.no-ip.org> writes: > 1. in VACUUM or brin_summarize_new_values, we only process fully loaded > ranges, and ignore the partial range at end of table.
OK. > 2. when summarization is requested on the partial range at the end of a > table, we acquire extension lock on the rel, then compute relation size > and run summarization with the lock held. This guarantees that we don't > miss any pages. This is bad for concurrency though, so it's only done > in that specific scenario. Hm, I wonder how this will play with the active proposals around reimplementing relation extension locks. All that work seems to be assuming that the extension lock is only held for a short time and nothing much beyond physical extension is done while holding it. I'm afraid that you may be introducing a risk of e.g. deadlocks if you do this. If VACUUM and brin_summarize_new_values both ignore the partial range, then what else would request this? Can't we just decree that we don't summarize the partial range, period? regards, tom lane -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers