Re: Problem with default partition pruning

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: yuzuko <yuzukohosoya(at)gmail(dot)com>
Cc: shawn wang <shawn(dot)wang(dot)pg(at)gmail(dot)com>, Shawn Wang <shawn(dot)wang(at)highgo(dot)ca>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Problem with default partition pruning
Date: 2019-08-05 14:39:20
Message-ID: 20190805143920.GA6232@alvherre.pgsql
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On 2019-Aug-05, yuzuko wrote:

> So I proposed moving the if() block to the current place.
> The latest patch can solve both queries but I found the latter
> problem can be solved by setting constraint_exclusion = on.

So we have three locations for that test; one is where it currently is,
which handles a small subset of the cases. The other is where Amit
first proposed putting it, which handles some additional cases; and the
third one is where your latest patch puts it, which seems to handle all
cases. Isn't that what Amit is saying? If that's correct (and that's
what I want to imply with the comment changes I proposed), then we
should just accept that version of the patch.

I don't think that we care about what happens with constraint_exclusion
is on. That's not the recommended value for that setting anyway.

Álvaro Herrera
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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