Date: Tue, 2 Jul 2019 11:49:28 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Julien Rouhaud <rjuju123@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
	Kevin Grittner <kgrittn@gmail.com>
Subject: Re: Add parallelism and glibc dependent only options to reindexdb
Message-ID: <20190702024928.GC1388@paquier.xyz>
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On Mon, Jul 01, 2019 at 06:28:13PM +0200, Julien Rouhaud wrote:
> On Mon, Jul 1, 2019 at 4:10 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Couldn't we make this enormously simpler and less bug-prone by just
>> dictating that --jobs applies only to reindex-table operations?

I had the same argument about the first patch sets actually, but... :)

> That would also mean that we'll have to fallback on doing reindex at
> table-level, even if we only want to reindex indexes that depends on
> glibc.  I'm afraid that this will often add a huge penalty.

Yes, I would expect that most of the time glibc-sensible indexes are
also mixed with other ones which we don't care about here.  One
advantage of the argument from Tom though is that it is possible to
introduce --jobs with minimal steps:
1) Refactor the code for connection slots, without the cell addition
2) Introduce --jobs without INDEX support.

In short, the conflict business between indexes is something which
could be tackled afterwards and with a separate patch.  Parallel
indexes at table-level has value in itself, particularly with
CONCURRENTLY coming in the picture.
--
Michael

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