Обсуждение: Re: [HACKERS] extended stats not friendly towards ANALYZE withsubset of columns
Re: [HACKERS] extended stats not friendly towards ANALYZE withsubset of columns
От
Alvaro Herrera
Дата:
David Rowley wrote: > ERROR: extended statistics could not be collected for column "a" of > relation public.ab1 > HINT: Consider ALTER TABLE "public"."ab1" ALTER "a" SET STATISTICS -1 > > I don't think the error is useful here, as it means nothing gets done. > Probably better to just not (re)build those stats. Agreed, an error there is a bad idea. > Another option would be to check for extended stats before deciding > which rows to ANALYZE, then still gathering the columns required for > MV stats, but I think if the user asks for a subset of columns to be > analyzed, and that causes a column to be missing for an extended > statistics, that it would be pretty surprising if we rebuild the > extended stats. That would be very surprising indeed. > Perhaps the SET STATISTIC 0 for a column still needs to gather data > for extended statistics, though. Perhaps a debate should ensue about > how that should work exactly. Hmm. I'd rather throw a warning at either CREATE STATISTICS time or at ALTER TABLE SET STATISTICS time, rather than magically changing the set of columns at analyze time. > I've attached a patch which fixes the problem above, but it does > nothing to change the analyze behaviour for 0 statistics columns. Pushed, after tweaking so that a WARNING is still emitted, because it's likely to be useful in pointing out a procedural mistake while extended stats are being tested. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
Re: [HACKERS] extended stats not friendly towards ANALYZE with subsetof columns
От
David Rowley
Дата:
On 18 April 2017 at 05:12, Alvaro Herrera <alvherre@2ndquadrant.com> wrote: > Pushed, after tweaking so that a WARNING is still emitted, because it's > likely to be useful in pointing out a procedural mistake while extended > stats are being tested. Thanks for pushing. Seems you maintained most of my original patch and added to it a bit, but credits don't seem to reflect that. It's not the end of the world but just wanted to note that. -- David Rowley http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services
Re: [HACKERS] extended stats not friendly towards ANALYZE withsubset of columns
От
Alvaro Herrera
Дата:
David Rowley wrote: > On 18 April 2017 at 05:12, Alvaro Herrera <alvherre@2ndquadrant.com> wrote: > > Pushed, after tweaking so that a WARNING is still emitted, because it's > > likely to be useful in pointing out a procedural mistake while extended > > stats are being tested. > > Thanks for pushing. > > Seems you maintained most of my original patch and added to it a bit, > but credits don't seem to reflect that. It's not the end of the world > but just wanted to note that. Yeah, sorry about that. Maybe we should start mentioning the percentage of the patch that comes from each author (just kidding). -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services