Date: Tue, 2 Jul 2019 12:12:40 +0200
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Julien Rouhaud <rjuju123@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
	Kevin Grittner <kgrittn@gmail.com>,
	Michael Paquier <michael@paquier.xyz>
Subject: Re: Add parallelism and glibc dependent only options to reindexdb
Message-ID: <20190702101240.dipk7wphmsoitlw3@development>
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On Tue, Jul 02, 2019 at 10:45:44AM +0200, Julien Rouhaud wrote:
>On Tue, Jul 2, 2019 at 10:28 AM Tomas Vondra
><tomas.vondra@2ndquadrant.com> wrote:
>>
>> I wonder why this is necessary:
>>
>> pg_log_error("cannot reindex glibc dependent objects and a subset of objects");
>>
>> What's the reasoning behind that? It seems like a valid use case to me -
>> imagine you have a bug database, but only a couple of tables are used by
>> the application regularly (the rest may be archive tables, for example).
>> Why not to allow rebuilding glibc-dependent indexes on the used tables, so
>> that the database can be opened for users sooner.
>
>It just seemed wrong to me to allow a partial processing for something
>that's aimed to prevent corruption.  I'd think that if users are
>knowledgeable enough to only reindex a subset of indexes/tables in
>such cases, they can also discard indexes that don't get affected by a
>collation lib upgrade.  I'm not strongly opposed to supporting if
>though, as there indeed can be valid use cases.
>

I don't know, it just seems like an unnecessary limitation.

>> BTW now that we allow rebuilding only some of the indexes, it'd be great
>> to have a dry-run mode, were we just print which indexes will be rebuilt
>> without actually rebuilding them.
>
>+1.  If we end up doing the filter in the backend, we'd have to add
>such option in the REINDEX command, and actually issue all the orders
>to retrieve the list.

Hmmm, yeah. FWIW I'm not requesting v0 to have that feature, but it'd be
good to design the feature in a way that allows adding it later.


regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services