Re: Data corruption zero a file - help!!

I've been watching the post: Re: [GENERAL] Fixing up a corrupted toast table
In there they mention deletion of the bad rows from the table based on
the citid. If I could come up with a def of a back row, would this
work, or are there other issues?

Cheers
Noel

Michael Fuhr wrote:
> On Thu, Mar 09, 2006 at 11:13:40AM +1100, Noel Faux wrote:
>
>> Ok it worked but we ran into another bad block :(
>> /vacuumdb: vacuuming of database "monashprotein" failed: ERROR: invalid
>> page header in block 9022937 of relation "gap"
>> /
>> So the command we used was:
>> dd bs=8k seek=110025 conv=notrunc count=1 if=/dev/zero
>> of=/usr/local/postgresql/postgresql-7.4.8/data/base/37958/111685332.68
>>
>> I'm tried to work out the formula for finding the file (i.e. the
>> 111685332.*) to fix and the value to seek to, but as a complete novice
>> I'm lost, any pointers would be a great help. We checked the block size
>> and it's 8192.
>>
>
> The database files are 1G, or 131072 8k blocks. The bad block you
> zeroed was 9022921; here's how you could have determined the file
> and block number within that file:
>
> test=> SELECT 9022921 / 131072 AS filenum, 9022921 % 131072 AS blocknum;
> filenum | blocknum
> ---------+----------
> 68 | 110025
> (1 row)
>
> The new bad block is 9022937 so the query would be:
>
> test=> SELECT 9022937 / 131072 AS filenum, 9022937 % 131072 AS blocknum;
> filenum | blocknum
> ---------+----------
> 68 | 110041
> (1 row)
>
> If you're running 7.4.8 then consider upgrading to 7.4.12. Offhand
> I don't know if any bugs have been fixed that might cause the problem
> you're seeing, but there have been other bug fixes.
>
>