Re: question on EXPLAIN_PLAN

From: Mike Killough <mwkillough_at_hotmail.com>
Date: Wed, 06 Feb 2002 13:50:13 -0800
Message-ID: <F001.004080AD.20020206135501@fatcity.com>

Kevin,

Have you analyzed the tables on both databases? Card is the CBO's estimate of the number of rows it will process.

Mike

>From: "kevin wang" <kwang_at_vivonet.com>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: question on EXPLAIN_PLAN
>Date: Wed, 06 Feb 2002 11:43:38 -0800
>
> Hi, guys
>
> The problem belows is really make me confused and gave me big trouble,
>is there someone can give me some hlep?
>
> I have two databses, same version(oracle 8.1.6),same O/S(win2000), same
>schema structure, different data(but small difference of size).
> and even exactly same explain_plan of my sql query.
> But on one database, the cardinality of one PK index access upon one
>table is 27(cost=2,card=27,bytes=756) (table rows 263758)
> and the other is 11706!!!! (cost=3,card=11706,bytes=199002)( table rows
>351173).
> so, on one DB the sql query took 300ms, one the other, it took 5
>seconds!
>
> Any advise is highly appreciated.
>
> thanks,
>
> Kevin Wang
> Database Administrator
> Vivonet Canada Inc.
>
>
>

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Author: Mike Killough
  INET: mwkillough_at_hotmail.com

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Received on Wed Feb 06 2002 - 15:50:13 CST