Re: [HACKERS] Proposal: Local indexes for partitioned table

From: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Maksim Milyutin <milyutinma(at)gmail(dot)com>
Subject: Re: [HACKERS] Proposal: Local indexes for partitioned table
Date: 2017-12-17 15:50:38
Message-ID: 20171217155037.c4r264w6wdy3zw2v@alvherre.pgsql
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Robert Haas wrote:
> On Fri, Dec 15, 2017 at 5:18 PM, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> > We have two options for marking valid:
> >
> > 1. after each ALTER INDEX ATTACH, verify whether the set of partitions
> > that contain the index is complete; if so, mark it valid, otherwise do
> > nothing. This sucks because we have to check that over and over for
> > every index that we attach
> >
> > 2. We invent yet another command, say
> > ALTER INDEX <idx-on-parent> VALIDATE
>
> If ALTER INDEX .. ATTACH is already taking AEL on the parent, then I
> think it might as well try to validate while it's at it. But if not
> then we might want to go with #2.

The problem I have with it is that restoring a dump containing indexes
on partitions becomes a O(N^2) deal as it has to do the full check once
for every index we attach.

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

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