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Re: Slow update with simple query

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Arnaud Lesauvage <thewild(at)freesurf(dot)fr>
Cc: Ragnar <gnari(at)hive(dot)is>, Jens Schipkowski <jens(dot)schipkowski(at)apus(dot)co(dot)at>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Slow update with simple query
Date: 2006-12-13 16:46:25
Message-ID: 8399.1166028385@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
Arnaud Lesauvage <thewild(at)freesurf(dot)fr> writes:
> Indeed, the new query does not perform that well :

> "Hash Join  (cost=112.75..307504.97 rows=2024869 width=355) (actual time=53.995..246443.811 rows=2020061 loops=1)"
> ...
> "Total runtime: 2777844.892 ms"

> I removed all unnecessary indexes on t1 before running the query (I left the index on uid and the multicolumn index containind the updated field).
> I believe the multicolumn-functional-index computation is taking some time here, isn't it ?

Given that the plan itself only takes 246 sec, there's *something*
associated with row insertion that's eating the other 2500+ seconds.
Either index entry computation or constraint checking ...

			regards, tom lane

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Next:From: Arnaud LesauvageDate: 2006-12-13 16:47:20
Subject: Re: Slow update with simple query
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Subject: Insertion to temp table deteriorating over time

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