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RE: Oracle slower ?

From: Bahar, Rivaldi (BBASSI-CHQ) <rivaldi.bahar_at_bbassi.com>
Date: Tue, 25 Feb 2003 09:30:09 -0800
Message-ID: <F001.00558CBE.20030225093009@fatcity.com>


Both Oracle (817) and Sybase running on the same test machine (Sun Solaris 6)
but in different mount point. Both not at optimum datafiles and I/O configuration.
If I run every SQL in the procedure manually from SQLplus it run at minimum cost
(explain plan), indexes used.

There are loops in the procedure. I guess it takes more time because more logic (if then else) inside the loops. For example, the following code generated
by OMWB is inside the loops.
Any other idea ?

IF ( TEST_4.TranFlag = 0) THEN
 BEGIN
   /* Emulating @@TRANCOUNT functionality in Oracle model */

	IF omwb_emulation.globalPkg.trancount = 1 THEN
	    COMMIT WORK;
	END IF;
	IF omwb_emulation.globalPkg.trancount > 0 THEN
	
omwb_emulation.globalPkg.trancount:=omwb_emulation.globalPkg.trancount-1;
	END IF;


-----Original Message-----
Sent: Tuesday, February 25, 2003 11:20 AM To: Multiple recipients of list ORACLE-L

>We are converting from SQL Server and Sybase to
>Oracle.
>To convert functions and stored procedures we have
>been using the
>Oracle Migration Workbench (OMWB) which produced
>WEAK REF CURSOR and
>TRANCOUNT global variable.
>I looked at (trace and explain plan) statements in
>the procedures
>and functions, it seems everything are OK. Init.ora
>parameters
>are big enough, statspack generated good values.
>The same function and procedure took about 1 minute
>
>in Sybase but take 9 minutes in Oracle. The
>difference is the procedures
>or functions after migration calling OMWB package
>(globalpkg).
>Any idea or tuning tips after migrating to Oracle ?
>
>Is Oracle slower than Sybase and SQL Server ?
>
>Tia.
>
>Rivaldi

I have had this kind of problem (only 8mn against 80mn) some months ago ... not exactly the same physical schema in Oracle as in Sybase :-). You cannot say that Oracle is inherently slower or faster than Sybase or SQL Server. It depends on a lot of things, the underlaying hardware, your application of course, the use of some 'native tricks' (and from experience IOTs are not exactly equivalent to clustered indexes). The problem is that automated tools may be good for a first pass, but you really need to dive in the code and tweak it manually if you want good results. A RDBMS is not the 'neutral' component you may think.
FYI we managed to bring Oracle performance in line (very slightly better, in fact) with Sybase performance in the case mentioned above. But it hasn't been easy.

HTH, Stephane Faroult
Oriole

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Author: Stephane Faroult
  INET: sfaroult_at_oriolecorp.com

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Author: Bahar, Rivaldi (BBASSI-CHQ)
  INET: rivaldi.bahar_at_bbassi.com

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Received on Tue Feb 25 2003 - 11:30:09 CST

Original text of this message

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