Re: WAL consistency check facility

From: Kuntal Ghosh <kuntalghosh(dot)2007(at)gmail(dot)com>
To: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Peter Geoghegan <pg(at)heroku(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Amit Kapila <amit(dot)kapila(at)enterprisedb(dot)com>
Subject: Re: WAL consistency check facility
Date: 2016-11-02 14:30:45
Message-ID: CAGz5QCKF1h24BAoybdBjwyP-Pcz5opgXYtOX1PJM0Jmxbh0zUQ@mail.gmail.com
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On Wed, Nov 2, 2016 at 1:11 PM, Kuntal Ghosh <kuntalghosh(dot)2007(at)gmail(dot)com> wrote:
> Rest of the suggestions are well-taken. I'll update the patch accordingly.
I've updated the last submitted patch(v10) with the following changes:
- added a block level flag BKPIMAGE_APPLY to distinguish backup image
blocks which needs to be restored during replay.
- at present, hash index operations are not WAL-logged. Hence, I've removed
the consistency check option for hash indices. It can be added later.

Few comments:
- Michael suggested to use an integer variable and bitwise-shift
operation to store
the RMGR values instead of using a boolean array. But, boolean array
implementation looks cleaner to me. For example,
+if (wal_consistency[rmid])
+ rechdr->xl_info |= XLR_CHECK_CONSISTENCY;

+include_image = needs_backup || wal_consistency[rmid];

- Another suggestion was to remove wal_consistency from PostgresNode.pm
because small buildfarm machines may suffer on it. Although I've no
experience in this matter, I would like to be certain that nothings breaks
in recovery tests after some modifications.

--
Thanks & Regards,
Kuntal Ghosh
EnterpriseDB: http://www.enterprisedb.com

Attachment Content-Type Size
walconsistency_v11.patch application/x-download 44.4 KB

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