From: | Amit Kapila <amit(dot)kapila(at)huawei(dot)com> |
---|---|
To: | "'Fujii Masao'" <masao(dot)fujii(at)gmail(dot)com> |
Cc: | "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "'Alvaro Herrera'" <alvherre(at)commandprompt(dot)com>, 'Cédric Villemain' <cedric(at)2ndquadrant(dot)com>, "'Pg Hackers'" <pgsql-hackers(at)postgresql(dot)org>, "'Robert Haas'" <robertmhaas(at)gmail(dot)com> |
Subject: | Re: Allow WAL information to recover corrupted pg_controldata |
Date: | 2012-06-20 03:40:53 |
Message-ID: | 002d01cd4e96$7ed399b0$7c7acd10$@kapila@huawei.com |
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Lists: | pgsql-hackers |
>> I believe if WAL files are proper as mentioned in Alvaro's mail, the
purposed logic should generate
>> correct values.
>> Do you see any problem in logic purposed in my original mail.
>> Can I resume my work on this feature?
> Maybe I'm missing your point, but... why don't you just use PITR to
> recover from the corruption of pg_control?
AFAIK PITR can be used in a scenario where there is a base back-up and we
have archived
the WAL files after that, now it can use WAL files to apply on base-backup.
In this scenario we don't know a point from where to start the next replay.
So I believe it will be difficult to use PITR in this scenario.
-----Original Message-----
From: Fujii Masao [mailto:masao(dot)fujii(at)gmail(dot)com]
Sent: Tuesday, June 19, 2012 7:44 PM
To: Amit Kapila
Cc: Tom Lane; Alvaro Herrera; Cédric Villemain; Pg Hackers; Robert Haas
Subject: Re: [HACKERS] Allow WAL information to recover corrupted
pg_controldata
On Tue, Jun 19, 2012 at 2:44 AM, Amit Kapila <amit(dot)kapila(at)huawei(dot)com> wrote:
>> AFAIR you can create pg_control from scratch already with pg_resetxlog.
>> The hard part is coming up with values for the counters, such as the
>> next WAL location. Some of them such as next OID are pretty harmless
>> if you don't guess right, but I'm worried that wrong next WAL could
>> make things worse not better.
>
> I believe if WAL files are proper as mentioned in Alvaro's mail, the
purposed logic should generate
> correct values.
> Do you see any problem in logic purposed in my original mail.
> Can I resume my work on this feature?
Maybe I'm missing your point, but... why don't you just use PITR to
recover from the corruption of pg_control?
Regards,
--
Fujii Masao
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