Re: Block Corruption issue..

Hi,

On 05/07/15 05:49, Sachin Srivastava wrote:
> Dear Concner,
>
> Could you help us solving the below error which we are getting during
> taking pg_dump.
>
> pg_dump: SQL command failed
>
> pg_dump: Error message from server: ERROR: invalid page header in block
> 14521215 of relation pg_tblspc/18140340/PG_9.1_201105231/18140346/18140757
>
> pg_dump: The command was: COPY evidence.partline (feature_id, version,
> base_type_id, domain_class_id, domain_subclass_id, status_id, deleted,
> modification_time, has_children, is_evidence, data_immediate, data_lazy,
> parent_line_id, start_point_id, end_point_id, start_offset, end_offset,
> geometry) TO stdout;

Well, it seems the data file got corrupted, for some reason. There's a
number of questions that need to be answered first:

1) ISTM you're running PostgreSQL 9.1 - correct? Which version exactly?
What operating system?

2) Which relation uses that particular filenode? Look for pg_class rows
with relfilenode 18140757.

3) Can you reconstruct the relation from other sources?

4) How did the corruption happen? Did the machine crash in the past, or
something like that?

5) How many cases of corruption are there? Is that a single corrupted
block, or are there more? I'd assume this is not the only corrupted
block, and other blocks may be corrupted in different ways.

You may use for example pageinspect to check that - for example
use page_header / heap_page_items to walk the pages, and take note
of pages that fail. It's not 100% solution, but it might give you a
better idea of how much corruption you're facing.

The easiest way to get rid of the error is to zero the page(s) that
cause the pg_dump errors. That page will then be considered empty,
so you'll loose that data (and you'll have to reconstruct that
somehow - from a previous backup. for example).

>
> Regards,
>
> Sachin Srivastava
>
>
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Sure ...

--
Tomas Vondra http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services