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Re: Database possible corruption , unsolvable mystery

From: "Eric Lauzon" <eric(dot)lauzon(at)abovesecurity(dot)com>
To: "stef" <stef(at)ummon(dot)com>
Cc: "Richard Huxton" <dev(at)archonet(dot)com>,<pgsql-performance(at)postgresql(dot)org>
Subject: Re: Database possible corruption , unsolvable mystery
Date: 2006-03-29 23:33:21
Message-ID: F7B73864DD39FA40B6C56B3CE0D4D1CBF007C4@asdc003.abovesecurite.lan (view raw or flat)
Thread:
Lists: pgsql-performance
> Hrm, you know that you -should- upgrade to at least the latest 7.4
> (7.4.13 I think is the most recent). looking from the 
> changelogs, there are a few bugs that you could be hitting;
> 
> 7.4.10
>     * Fix race condition in transaction log management There 
> was a narrow window in which an I/O operation could be 
> initiated for the wrong page, leading to an Assert failure or 
> data corruption.
> 
> 7.4.9
>     * Improve checking for partially-written WAL pages
>     * Fix error that allowed VACUUM to remove ctid chains too 
> soon, and add more checking in code that follows ctid links. 
> This fixes a long-standing problem that could cause crashes 
> in very rare circumstances.
> 
> 7.4.8
>     * Repair race condition between relation extension and 
> VACUUMThis could theoretically have caused loss of a page's 
> worth of freshly-inserted data, although the scenario seems 
> of very low probability. There are no known cases of it 
> having caused more than an Assert failure
> 
>     and these are only the ones that appear 'notably' in the 
> changelog. 
> In short, I -really- -would- -strongly- -advise- you 
> upgrading to 7.4.13. Personally, I would have made this my 
> first step, especially if your data is important.
> 
>     There is no need for a dump/reload between minor point releases. 
> Although there is a security fix in 7.4.8.
> 
>     Since the db is in a state of 'down' or repair, why not 
> do it now ? 
> two birds, one stone.

Thank you , this might be a good solution , but we have a bigger upgrade
comming for 8.1.x later on,
but considering that other things out of our hands might occur , we
might seriously look into it after fixing
the current problems :) [because we dont think that upgrading right now
will magicly fix the problem we are having.]
And on about 10 database [all 7.4.6] it is the first time this occur ,
and the symtom is really on one table, considering
a few terabytes of data sparsed accros a few db, we might have been
lucky yet but as of now its the first time 
we can see performance hit only on "delete".

But thanks alot for the hint. [even tho we never had some unexpected
data failure/crash] beside this out of control
human power failure that might have been the root of this [the database
is still dumping ...few gigs :)]

Thanks alot all for the help,and if we find the root cause we will give
feed back.

-elz

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