Re: Detecting corrupted pages earlier - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Detecting corrupted pages earlier
Date
Msg-id 6086.1049056148@sss.pgh.pa.us
Whole thread Raw
In response to Re: Detecting corrupted pages earlier  (Kevin Brown <kevin@sysexperts.com>)
Responses Re: Detecting corrupted pages earlier  (Kevin Brown <kevin@sysexperts.com>)
List pgsql-hackers
Kevin Brown <kevin@sysexperts.com> writes:
> Tom Lane wrote:
>> Basically, one should only turn this variable on after giving up on the
>> possibility of getting any data out of the broken page itself.  It would
>> be folly to run with it turned on as a normal setting.

> This statement should *definitely* go into the documentation for the
> option, then...

Here's what I put in --- feel free to suggest better wording.

ZERO_DAMAGED_PAGES (boolean)
    Detection of a damaged page header normally causes PostgreSQL to    report an error, aborting the current
transaction.Setting    zero_damaged_pages to true causes the system to instead report a    warning, zero out the
damagedpage, and continue processing. This    behavior <emphasis>will lose data</>, namely all the rows on the
damagedpage. But it allows you to get past the error and retrieve    rows from any undamaged pages that may be present
inthe table. So    it is useful for recovering data if corruption has occurred due to    hardware or software error.
Thedefault setting is off, and it can    only be changed by a superuser.
 

        regards, tom lane



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