Re: Does primary key structure impact UPDATE performance?

From: Tanel Põder <tanel.poder.003_at_mail.ee>
Date: Mon, 17 May 2004 18:47:26 +0300
Message-ID: <1ce801c43c26$415611c0$fda423d5@porgand>

Assuming, that you're running on decent CPUs, it seems strange that 2371 consistent reads and 1 current read require 1,72 seconds of CPU time (even in the very unlikely event when CPU usage between every physical IO would heve been overaccounted due quantization error).

This PL/SQL loop, does it open a cursor and keep it open for a long time? That way several rollback segment block gets might be required to satisfy a consistent read, that could explain high CPU usage per LIO in extreme cases. (But it wouldn't explain why there is such a difference between two tables w. different indexes).

Maybe query definitions + execution plans would give some more clues...

Tanel.

Original Message ----- From: "Khedr, Waleed" <Waleed.Khedr_at_FMR.COM> To: <oracle-l_at_freelists.org> Sent: Monday, May 17, 2004 5:18 PM Subject: RE: Does primary key structure impact UPDATE performance?

> This should be found easily by getting the execution plan out of the =
> trace file (the STATS lines) and see if there is a UNIQUE SCAN or =
> something else.
>
> Waleed
>

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Received on Mon May 17 2004 - 10:48:25 CDT