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Re: Slow UPADTE, compared to INSERT

From: Ivar Zarans <iff(at)alcaron(dot)ee>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Slow UPADTE, compared to INSERT
Date: 2003-12-04 20:43:26
Message-ID: 20031204204326.GA17083@alcaron.ee (view raw or flat)
Thread:
Lists: pgsql-performance
On Thu, Dec 04, 2003 at 08:23:36PM +0000, Richard Huxton wrote:

> Ah - it's probably not the update but the IN. You can rewrite it using PG's 
> non-standard FROM:
> 
> UPDATE t1 SET status='done' FROM t_tmp WHERE t1.rec_id = t_tmp.rec_id;

Thanks for the hint. I'll try this.

> Now that doesn't explain why the update is taking so long. One fifth of a 
> second is extremely slow. Are you certain that the index is being used?

Explain shows following output:

explain update table1 set status = 'PROC' where recid = '199901';

Index Scan using table1_pkey on table1  (cost=0.00..6.01 rows=1 width=198)
   Index Cond: (recid = 199901::bigint)
   (2 rows)



-- 
Ivar Zarans


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