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Re: Deleting Records

From: Nörder-Tuitje, Marcus <noerder-tuitje(at)technology(dot)de>
To: "Christian Paul B(dot) Cosinas" <cpc(at)cybees(dot)com>,<pgsql-performance(at)postgresql(dot)org>
Subject: Re: Deleting Records
Date: 2005-10-20 08:50:50
Message-ID: 16F953410A0F1346848DCB476A989CFE01D559@swtexchange2.technology.de (view raw or flat)
Thread:
Lists: pgsql-performance
what about firing a 

DELETE FROM qc_session S 
       WHERE EXISTS (SELECT * 
                       FROM item_qc_doer i
                      WHERE i.item_id = s.item_id);

and 

DELETE FROM item_qc_doer S 
       WHERE EXISTS (SELECT * 
                       FROM item_qc_doer i
                      WHERE i.item_id = s.item_id);


this might be faster.

another way to speed up deletes might be disabling foreign keys.

also a SET ENABLE_SEQSCAN=FALSE; can speed up queries (force use of indices for access)


do you have a EXPLAIN for us ? do you have a index on item_id on your tables ?

questions by questions ;-)



mfg


-----Ursprüngliche Nachricht-----
Von: pgsql-performance-owner(at)postgresql(dot)org
[mailto:pgsql-performance-owner(at)postgresql(dot)org]Im Auftrag von Christian
Paul B. Cosinas
Gesendet: Donnerstag, 20. Oktober 2005 10:44
An: pgsql-performance(at)postgresql(dot)org
Betreff: [PERFORM] Deleting Records


Hi!

I'm experiencing a very slow deletion of records. Which I thin is not right.
I have a Dual Xeon Server with 6gig Memory.
I am only deleting about 22,000 records but it took me more than 1 hour to
finish this.

What could possibly I do so that I can make this fast?

Here is the code inside my function:

	FOR temp_rec IN SELECT * FROM item_qc_doer LOOP
		DELETE FROM qc_session WHERE item_id = temp_rec.item_id;
		DELETE FROM item_qc_doer WHERE item_id = temp_rec.item_id;
	END LOOP;

Item_qc_oder table contains 22,000 records.


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Subject: Re: Deleting Records
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