Re: Needless additional partition check in INSERT?

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com>, Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com>
Subject: Re: Needless additional partition check in INSERT?
Date: 2018-06-08 15:24:20
Message-ID: 20180608152420.atzaxbml6m2st5ql@alvherre.pgsql
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On 2018-Jun-07, David Rowley wrote:

> On 7 June 2018 at 15:57, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> wrote:
> > Hm I was thinking this new function would be companion to ExecConstrains
> > (a fact I used in the name I proposed,) so it'd be in the same file
> > (probably right after it.)
>
> Okay. v5 (attached) does it that way.

Thanks, looks nice (function name is stupidly long, my fault).

I wondered about the refactoring that Amit Khandekar is proposing.
Given the improved API you gave the new function, it appears we can
write it like this (untested):

bool
ExecConstraintsPartConstrNeedsRecheck(ResultRelInfo *resultRelInfo,
bool tupleRouting)
{
if (tupleRouting)
{
if (resultRelInfo->ri_TrigDesc &&
resultRelInfo->ri_TrigDesc->trig_insert_before_row)
return true;
}
else if (resultRelInfo->ri_PartitionCheck != NIL)
return true;

return false; /* no need to recheck */
}

I was also wondering about introducing a new function call in this path
where previously was none. Given the amount of other stuff that's
happening when a tuple is inserted, I suppose it's not worth worrying
about in terms of making this an inline function in the header.

BTW I noticed that ExecConstraints() indicates that the given
resultRelInfo is "the original resultRelInfo, before tuple routing", but
that's demostrably false. What's up with that?

--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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