Simon Riggs wrote: > * For emergency anti-wraparound VACUUMs we shouldn't scan indexes at all, > since they aren't critical path activities at that point
It is not possible to skip scanning indexes completely, unless no tuples are to be removed from the heap. Otherwise, index tuples become lingering pointers (and when such heap address are later refilled, they become corrupted indexscans). But actually this is an interesting point and I don't think we do this: if in emergency mode, maybe we shouldn't try to remove any dead tuples at all, and instead only freeze very old tuples. That would make such vacuums go much quicker. (More accurately, if the updating xid is older than the freeze point, then remove the tuple, but otherwise keep it.) My point is that emergency vacuums are troublesome for various reasons and it would be better if they did only the minimum possible. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
