Re: Invalid page header

On Wednesday October 20 2004 5:34, Ed L. wrote:
> I have 5 corrupted page headers as evidenced by these errors:
>
>     ERROR:  Invalid page header in block 13947 of ...
>
> The corruption is causing numerous queries to abort.  First option is to
> try to salvage data before attempt restore from backup.  I want to try to
> edit the file to zero out the bogus headers.  I realize there may be data
> lost from this attempt.  I have scalpel (binary editor) in hand.
>
> Which bytes should I edit, and what do I make them?

In other words, how do I calculate which bytes to zero to simulate
zero_damaged_pages??

TIA.


>
>
> $ pg_filedump -if -R 1343 1343 25268878.38650946
>
> *****************************************************************
> * PostgreSQL File/Block Formatted Dump Utility - Version 1.1
> *
> * File: 25268878.38650946
> * Options used: -if -R 1343 1343
> *
> * Dump created on: Wed Oct 20 19:14:06 2004
> *****************************************************************
>
> Block 1343 ******************************************************
> <Header> -----
>  Block Offset: 0x00a7e000         Offsets: Lower       0 (0x0000)
>  Block: Size    0  Version    0            Upper       0 (0x0000)
>  LSN:  logid      0 recoff 0x00000000      Special     0 (0x0000)
>  Items:   -5                   Free Space:    0
>  Length (including item array): 24
>
>  Error: Invalid header information.
>
>   0000: 00000000 00000000 00000000 00000000  ................
>   0010: 00000000 00000000                    ........
>
> <Data> ------
>  Error: Item index corrupt on block. Offset: <-5>.
>
> <Special Section> -----
>  Error: Invalid special section encountered.
>  Error: Special section points off page. Unable to dump contents.
>
> *** End of Requested Range Encountered. Last Block Read: 1343 ***