Re: ERROR invalid page header in block xxx of relation base/xxxxx/xxxxx/

Look into this setting.

zero_damaged_pages = on;

The docs should explain it.

On Wed, Dec 7, 2016 at 2:47 PM, sreekanth Palluru <sree4pg(at)gmail(dot)com> wrote:

> Hi ,
>
> I am getting invalid page header error and what I could observe is when I
> select the table I get this error , where as if I select table and order by
> primary key I can retrieve the rows from table.
>
> And I don't see any dataloss ( based on total number records) after fixing
> the blocks using zero_damaged_pages=on and then vacuum full on the table
>
>
> Please note I have renamed few tables to avoid giving actual table names
>
> We run Postgres 9.2 version on Windows and Dell Optiplex XE2 server and we
> suspect that block corruption would have happen due to
> hardware/memory/power failures reasons and I have gone through wikik
> https://wiki.postgresql.org/wiki/Reliable_Writes.
>
> I want to understand why we can read the table through where there exists
> index and explain plan shows Index scan and with high cost compare to seq
> scan .
> I assume that since there no rows/data present in these corrupted blocks
> index scan skips these blocks and hence it is not throwing the error .
>
> Also , I want to know what would have caused the postgres to create these
> corrupted blocks and
> can I reproduce this error ? appreciate if you share any pointers to
> blogs/mailing lists if this type of issue is already discussed ?
>
>
> create table a.parametertable_bak as select * from a.parametertable order
> by id;
>
> labs=# select count(*) from a.parametertable_bak ;
> count
> -------
> 31415
> (1 row)
>
>
> labs=#
> labs=# checkpoint;
> CHECKPOINT
> labs=# set zero_damaged_pages=on;
> SET
> labs=# vacuum full a.parametertable;
> WARNING: invalid page header in block 204 of relation base/16413/16900;
> zeroing out page
> WARNING: invalid page header in block 205 of relation base/16413/16900;
> zeroing out page
> VACUUM
> labs=# select count(*) from a.parametertable ;
> count
> -------
> 31415
> (1 row)
>
>
> labs=#
> -Sreekanth
>

--
Thanks,

Jorge Torralba
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