Re: speeding up planning with partitions

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
Cc: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Imai Yoshikazu <yoshikazu_i443(at)live(dot)jp>, "jesper(dot)pedersen(at)redhat(dot)com" <jesper(dot)pedersen(at)redhat(dot)com>, "Imai, Yoshikazu" <imai(dot)yoshikazu(at)jp(dot)fujitsu(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: speeding up planning with partitions
Date: 2019-03-28 05:03:21
Message-ID: 19663.1553749401@sss.pgh.pa.us
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Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> writes:
> On 2019/03/27 23:57, Tom Lane wrote:
>> Yeah, there's something to be said for having plancat.c open each table
>> *and store the Relation pointer in the RelOptInfo*, and then close that
>> again at the end of planning rather than immediately. If we can't avoid
>> these retail table_opens without a great deal of pain, that's the
>> direction I'd tend to go in. However it would add some overhead, in
>> the form of a need to traverse the RelOptInfo array an additional time.

> Just to be sure, do you mean we should do that now or later (David said
> "in the long term")?

It's probably not high priority, though I wonder how much time is being
eaten by the repeated table_opens.

regards, tom lane

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