Kevin Grittner wrote: > On Tue, May 24, 2016 at 12:00 PM, Andres Freund <and...@anarazel.de> wrote: > > On 2016-05-24 11:24:44 -0500, Kevin Grittner wrote: > >> On Fri, May 6, 2016 at 8:28 PM, Kevin Grittner <kgri...@gmail.com> wrote: > >>> On Fri, May 6, 2016 at 7:48 PM, Andres Freund <and...@anarazel.de> wrote: > >> > >>>> That comment reminds me of a question I had: Did you consider the effect > >>>> of this patch on analyze? It uses a snapshot, and by memory you've not > >>>> built in a defense against analyze being cancelled. > > The primary defense is not considering a cancellation except in 30 > of the 500 places a page is used. None of those 30 are, as far as > I can see (upon review in response to your question), used in the > analyze process.
I think what this means is that vacuum might remove tuples that would otherwise be visible to analyze's snapshot. I suppose that's acceptable. I wondered if it could cause harm to the size of the sample, but after looking at acquire_sample_rows briefly I think it'd be unharmed. -- 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
