Re: initdb -S and tablespaces

From: Andres Freund <andres(at)2ndquadrant(dot)com>
To: Abhijit Menon-Sen <ams(at)2ndQuadrant(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: initdb -S and tablespaces
Date: 2014-09-29 09:54:10
Message-ID: 20140929095410.GC4716@alap3.anarazel.de
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On 2014-09-29 14:09:01 +0530, Abhijit Menon-Sen wrote:
> Hi.
>
> I just noticed that initdb -S ("Safely write all database files to disk
> and exit") does (only) the following in perform_fsync:
>
> pre_sync_fname(pdir, true);
> walkdir(pg_data, pre_sync_fname);
>
> fsync_fname(pdir, true);
> walkdir(pg_data, fsync_fname);
>
> walkdir() reads the directory and calls itself recursively for S_ISDIR
> entries, or calls the function for S_ISREG entries… which means it
> doesn't follow links.
>
> Which means it doesn't fsync the contents of tablespaces.

Which means at least pg_upgrade is unsafe right
now... c.f. 630cd14426dc1daf85163ad417f3a224eb4ac7b0.

Note that the perform_fsync() *was* ok for its original purpose in
initdb. At the end of initdb there's no relevant tablespaces. But if
used *after* pg_upgrade, that's not necessarily the case.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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