Re: Corrpupt Data File

for the annals of postgres maintenance I got my DB running by using DD to
copy the blocks before the corrupt block, then add block from /dev/zero,
then add the remaining blocks from the file. I discovered the block size
by looking at he output of pg_filedump. To find the offending file select
rel_filename from pg_class where relname = TABLE_NAME.

My original error was : "ERROR: Invalid page header in block 57879 of
orders" -- thus the bad block is #57879

cp 309928249 orders.bak
dd bs=8192 count=57879 if=309928249 of=out
dd bs=8192 count=1 seek=57879 if=/dev/zero of=out
dd bs=8192 skip=57880 seek=57880 if=309928249 of=out
mv out 309928249

Many thanks to Tom for his quick reply & Good luck to all others.

Thanks,
-Alex

On Thu, 26 Feb 2004, Tom Lane wrote:

> Alex Derbes <acd(at)brillig(dot)org> writes:
> > deleting the indexes from the table did not help. Is there a tool or
> > method that that I could use to simply skip the bad data and at least
> > recover the good blocks?
>
> Just zero out the broken page, eg with dd from /dev/zero. Note it
> might be a good idea to shut down the postmaster while you do so,
> else there could be a copy of that page in Postgres shared buffers,
> which'd mask your attempted fix.
>
> regards, tom lane
>

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