[PERFORM] No hash join across partitioned tables?
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From: Robert Haas on 10 Jun 2010 09:29 (moving to -hackers) On Wed, Jun 9, 2010 at 4:11 PM, Tom Lane <tgl(a)sss.pgh.pa.us> wrote: > Robert Haas <robertmhaas(a)gmail.com> writes: >> In going back through emails I had marked as possibly needing another >> look before 9.0 is released, I came across this issue again. �As I >> understand it, analyze (or analyse) now collects statistics for both >> the parent individually, and for the parent and its children together. >> �However, as I further understand it, autovacuum won't actually fire >> off an analyze unless there's enough activity on the parent table >> considered individually to warrant it. �So if you have an empty parent >> and a bunch of children with data in it, your stats will still stink, >> unless you analyze by hand. > > Check. > >> Assuming my understanding of the problem is correct, we could: > >> (a) fix it, >> (b) document that you should consider periodic manual analyze commands >> in this situation, or >> (c) do nothing. > >> Thoughts? > > The objections to (a) are that it might result in excessive ANALYZE work > if not done intelligently, and that we haven't got a patch ready anyway. > I would have liked to get to this for 9.0 but I feel it's a bit late > now. I guess I can't really disagree with that. Should we try to document this in some way? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
From: Robert Haas on 13 Jun 2010 23:47 On Thu, Jun 10, 2010 at 9:29 AM, Robert Haas <robertmhaas(a)gmail.com> wrote: > (moving to -hackers) > > On Wed, Jun 9, 2010 at 4:11 PM, Tom Lane <tgl(a)sss.pgh.pa.us> wrote: >> Robert Haas <robertmhaas(a)gmail.com> writes: >>> In going back through emails I had marked as possibly needing another >>> look before 9.0 is released, I came across this issue again. As I >>> understand it, analyze (or analyse) now collects statistics for both >>> the parent individually, and for the parent and its children together. >>> However, as I further understand it, autovacuum won't actually fire >>> off an analyze unless there's enough activity on the parent table >>> considered individually to warrant it. So if you have an empty parent >>> and a bunch of children with data in it, your stats will still stink, >>> unless you analyze by hand. >> >> Check. >> >>> Assuming my understanding of the problem is correct, we could: >> >>> (a) fix it, >>> (b) document that you should consider periodic manual analyze commands >>> in this situation, or >>> (c) do nothing. >> >>> Thoughts? >> >> The objections to (a) are that it might result in excessive ANALYZE work >> if not done intelligently, and that we haven't got a patch ready anyway. >> I would have liked to get to this for 9.0 but I feel it's a bit late >> now. > > I guess I can't really disagree with that. Should we try to document > this in some way? Proposed patch attached. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company
From: Robert Haas on 15 Jun 2010 14:44 On Sun, Jun 13, 2010 at 11:47 PM, Robert Haas <robertmhaas(a)gmail.com> wrote: > Proposed patch attached. Hearing no objections, I have committed this patch. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise Postgres Company -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
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