Home » RDBMS Server » Performance Tuning » Oracle runs SLOWER on XEON than Pentium Dual (Oracle 8.1, Windows 2003 Server)
Oracle runs SLOWER on XEON than Pentium Dual [message #334570] Thu, 17 July 2008 02:59 Go to next message
tranzicija
Messages: 3
Registered: July 2008
Location: Belgrade, Serbia
Junior Member

Hey guys and gals, I have a weird problem concerning performance issues of our two Oracle servers.

One server runs on a XEON based machine, with 2 XEON 3GHz processors and 512MB RAM, and the other on Intel Pentium Dual Core 1.6 GHz processor with 1GB RAM.

They both run the same database, the same operating system, and Oracle 8.1.

The problem is that the XEON machine seems to be SLOWER (the same query takes 3 secs on it, and only 1 sec on the Pentium, it's the same with other queries, just different time ratios).

We tried rebuilding the indexes on the tables used in a test query, but got no increase in performance.

I know that it sounds impossible, but it is true. Is there an out-of-the-box solution for this, since the databases are identical (one restored to another server).

Thanks.
Re: Oracle runs SLOWER on XEON than Pentium Dual [message #334571 is a reply to message #334570] Thu, 17 July 2008 03:03 Go to previous messageGo to next message
JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...
Senior Member
Do they both have Stats generated at the same point?

Can you post Explain Plans for the same wuery from both databases?
Re: Oracle runs SLOWER on XEON than Pentium Dual [message #334572 is a reply to message #334571] Thu, 17 July 2008 03:06 Go to previous messageGo to next message
JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...
Senior Member
Looking at the details you posted, it's probably the memory that's killing your Xeon box. What OS do you have on it?

Re: Oracle runs SLOWER on XEON than Pentium Dual [message #334577 is a reply to message #334572] Thu, 17 July 2008 03:43 Go to previous messageGo to next message
tahpush
Messages: 961
Registered: August 2006
Location: Stockholm/Sweden
Senior Member

The topic says
Quote:
Oracle runs SLOWER on XEON than Pentium Dual (Oracle 8.1, Windows 2003 Server)
Smile

Do both these databases, have the same memory configuration ?
Re: Oracle runs SLOWER on XEON than Pentium Dual [message #334590 is a reply to message #334570] Thu, 17 July 2008 04:44 Go to previous messageGo to next message
tranzicija
Messages: 3
Registered: July 2008
Location: Belgrade, Serbia
Junior Member

I must admit I have little knowledge of Oracle, and nothing was specialy configured for either server.

Both servers run Windows 2003 Server, and on both servers Oracle 8.1 was installed and databases restored. That alone presented us with the query speed disparity, and then we tried reindexing the tables that were used in the query, on the slower, XEON server (which shouldn't be slower !!!), but with no luck.

Explain plans are attached below.

jps_mega represents the faster server, jps_test is the slower one (running on XEON).

[Updated on: Thu, 17 July 2008 05:02]

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Re: Oracle runs SLOWER on XEON than Pentium Dual [message #334596 is a reply to message #334590] Thu, 17 July 2008 05:21 Go to previous messageGo to next message
JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...
Senior Member
The first observation is that you've not gathered statistics on the Xeon box.

Connect as a Dba and run
BEGIN
  DBMS_STATS.GATHER_SCHEMA_STATS(ownname => '&schema_to_analyse'
                                ,method_opt => 'FOR ALL INDEXED COLUMNS SIZE AUTO'
                                ,cascade => true);
END;
/


Depending on what edition (Standard, Enterprise, Datacentre) of 2003 you're running with, the OS can require upto 512MB of RAM.
Re: Oracle runs SLOWER on XEON than Pentium Dual [message #334597 is a reply to message #334596] Thu, 17 July 2008 05:22 Go to previous messageGo to next message
JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...
Senior Member
The other point is that a query unlikely to be CPU bound, so the increased processing speed will make little difference.
I/O speed is going to be the determining factor - what disc configurations do you have for the two boxes?
Re: Oracle runs SLOWER on XEON than Pentium Dual [message #334631 is a reply to message #334570] Thu, 17 July 2008 08:09 Go to previous message
tranzicija
Messages: 3
Registered: July 2008
Location: Belgrade, Serbia
Junior Member

We've managed to speed up the server a little by changing the sort_memory and sort_memory_area settings, but it seems that the RAM is the main issue. 512MB is not even enough for the OS to work flawlessly, let alone running Oracle on it.

Thank you guys for your quick response and input.
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