On Tue, Jan 13, 2015 at 8:16 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > I wrote: >> Heikki Linnakangas <hlinnakan...@vmware.com> writes: >>> But do we really need to backpatch any of this? > >> Alexey's example consumes only a couple hundred MB in 9.2, vs about 7GB >> peak in 9.3 and up. That seems like a pretty nasty regression. > > I did a bit more measurement of the time and backend memory consumption > for Alexey's example EXPLAIN: > > 9.2: 0.9 sec, circa 200 MB > HEAD: 56 sec, circa 7300 MB > with patch below: 3.7 sec, circa 300 MB > > So while this doesn't get us all the way back down to where we were before > we started trying to guarantee unique table/column identifiers in EXPLAIN > printouts, it's at least a lot closer. > > Not sure whether to just commit this to HEAD and call it a day, or to > risk back-patching.
I think we need to back-patch something; that's a pretty nasty regression, and I have some EDB-internal reports that might be from the same cause. I'm not too concerned about forcibly breaking the API here, but I can understand why somebody might want to do that. If we do, I like the idea of renaming ExplainInitState() or maybe by replacing it by a NewExplainState() function that is used instead. But I'm not sure how necessary it is really. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
