Re: speeding up planning with partitions

From: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: 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>, David Rowley <david(dot)rowley(at)2ndquadrant(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: 2019-03-27 05:13:42
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On 2019/03/27 13:50, Amit Langote wrote:
> On 2019/03/27 12:06, Amit Langote wrote:
>> I wonder if I should rework inherit.c so that its internal interfaces
>> don't pass around parent Relation, but make do with the RelOptInfo? I'll
>> need to add tupdesc and reltype fields to RelOptInfo to go ahead with that
>> though.
> To give more context on the last sentence, the only place we need the
> TupleDesc for is make_inh_translation_list(). Maybe, instead of adding
> tupdesc to RelOptInfo, we could add a List of Vars of all attributes of a
> table. To avoid the overhead of always setting it, maybe we could set it
> only for inheritance parent tables. Adding tupdesc to RelOptInfo might be
> a hard sell to begin with, because it would need to be pinned and then
> released at the end of planning.
> I'll see if I can make this work.

Hmm, scratch that. We'd need to keep around the attribute names too for
comparing with the attribute names of the children during translation.
Maybe we could store TargetEntry's in the list instead of just Vars, but
maybe that's too much.

Furthermore, if we make make_inh_translation_list too dependent on this
stuff, that will make it hard to use from inheritance_planner(), where we
expand the target inheritance without having created any RelOptInfos.


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