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Database possible corruption , unsolvable mystery

From: "Eric Lauzon" <eric(dot)lauzon(at)abovesecurity(dot)com>
To: <pgsql-performance(at)postgresql(dot)org>
Subject: Database possible corruption , unsolvable mystery
Date: 2006-03-29 17:58:59
Message-ID: F7B73864DD39FA40B6C56B3CE0D4D1CBF00796@asdc003.abovesecurite.lan (view raw or flat)
Thread:
Lists: pgsql-performance
Greetings,

	We have an issue where we have a database with many tables.
	The layout of the database is 3 set of look alike tables with different names.
	Each set of tables has some referential integrety that point back to the main
	control table.

	On two set of tables we are able to efficiently delete referential and main record
	without a problems, but on the 3rd set we have an issue where the control table is clugged
	and delete seem to take forever , as example on the first two set a delete of 60K record take about
	4 second to 10 second but on the 3rd set it can take as long as 3hours.

	This seem to be only affecting one database , the schema and way of doing is replicated elsewhere
	and if efficient.

	The question is, even after droping 3rd set integrity , dumping the table data , deleting the table,
	doing a manual checkpoint and recreating the table with the dump data , with or without referential
	integrity , the problems still araise.

	If we copy the data from the live table and do a create table aaa as select * from problematic_table;
	the table aaa operations are normal and efficient.

	This is why our investigation brought us to the folowing questions:

	1. Are postgresql data file name are hashed references to table name(as oracle)? [~path to data EX:/var/log/pgsql/data/[arbitraty   			   numbers]/[datafile]]?

	2. If the data files are corrupted and we re-create is it possible it uses the same files thus creating the same issue?

 	3. Since we know that all the tables has that problems is there an internal table with undisclosed references to tables data files?
	
	I hope the questions were clear.

	Have a good day, and thank you in advance.


Eric Lauzon
[Recherche & Développement]
Above Sécurité / Above Security
Tél  : (450) 430-8166
Fax : (450) 430-1858

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Subject: Re: Database possible corruption , unsolvable mystery
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