RE: Oracle Performance

My guess is that SQL Server is by default using 3 indexes to resolve the
query
    COD_IMPORTACION, NRO_FACTURACION and COD_NIVEL_CALIDAD whereas Oracle is
only using one (or performing a full-table scan).
 
Have you gernerated statistics on the tables? Can you post the explain plan
for the Oracle query?. 
 
Several tuning stragegies can be used..
1)    create a composite index on the 3 columns (COD_IMPORTACION,
COD_NIVEL_CALIDAD, NRO_FRACTURACION).
2)    Try the  index_combine hint to try to force oracle to use the 3
indexes.
3)    Try FIRST_ROWS hint in a inline view
        SELECT /*+NO_MERGE(x) */ COUNT(NRO_FACTURACION) 
        FROM (SELECT /*+ FIRST_ROWS */ nro_facturacion from sc_facturacion
WHERE ...) x
 
HTH
Kevin.
 
 
 
-----Original Message-----
From: Khedr, Waleed [mailto:Waleed.Khedr@xxxxxxx] 
Sent: Thursday, March 11, 2004 8:57 AM
To: 'oracle-l@xxxxxxxxxxxxx'
Subject: RE: Oracle Performance


You should be able to cache all the data in these two tables in the buffer
cache.
Increase your buffer cache settings to 200M-300M and set the degree of
parallelism to 1 for the two tables.
 
Send us the init.ora file.
 
Waleed
-----Original Message-----
From: Huascar Espinoza [mailto:hespinoza@xxxxxxxxxxxxxxx]
Sent: Thursday, March 11, 2004 8:35 AM
To: oracle-l@xxxxxxxxxxxxx
Cc: VChoque
Subject: RE: Oracle Performance


To realize the test, we have the basic following structure (similar on
Oracle 9i and SQL Server 7.0):
 

 
*        Table "SC_FACTURACION" have the following indexes:
*       COD_IMPORTACION 

*       NRO_FACTURACION 

*       COD_FACTURA_ESTIMADA 

*       COD_FACTURA_REFACTURADA 

*       COD_MOTIVO_ESTIMACION 

*       COD_NIVEL_CALIDAD. 
*        Table "GE_HISTORICO_IMPORTACION" has 30 registers.
*        Table "SC_FACTURACION" has 1,885,618 registers.
 
On 'SC_FACTURACION' we execute the following SQL sentences:
 
1.      SELECT COUNT(NRO_FACTURACION) FROM SC_FACTURACION WHERE
COD_IMPORTACION = '14' AND COD_NIVEL_CALIDAD = '1' 

2.      SELECT MAX(NRO_FACTURACION) FROM SC_FACTURACION WHERE
COD_IMPORTACION = '14' AND COD_NIVEL_CALIDAD = '1' 

3.      SELECT MIN(NRO_FACTURACION) FROM SC_FACTURACION WHERE
COD_IMPORTACION = '14' AND COD_NIVEL_CALIDAD = '1' 
 
The results are:
 

Sentence
Performance ORACLE 9i 
Performance MS SQL Server 7.0

1
2 minutes
20 secs.

2
2 minutes
1 sec.

3
50 secs.
1 secs.
 
The servers are the followins features:
 
ORACLE 9i Server

Processor
Intel Pentium IV - 2.4 GHz

RAM Memory
512 MB
 
S SQL Server 7.0 Server

Processor
Intel Celeron 2.4 GHz

RAM Memory
380 MB
 
 
Please let me know, why the performance of Oracle is so low.
 
Thank you!
 
Huáscar Espinoza
 
 
-----Mensaje original-----
De: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] En
nombre de DENNIS WILLIAMS
Enviado el: Jueves 11 de Marzo de 2004 9:16
Para: 'oracle-l@xxxxxxxxxxxxx'
Asunto: RE: Oracle Performance
 
Huascar
     Normal? No. In order to help diagnose your situation, please post more
details. Like your query, the sizes of your tables, etc. Have you analyzed
the tables in Oracle? 
 
 
 
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams@xxxxxxxxxxxxx 
 
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]On
Behalf Of Huascar Espinoza
Sent: Thursday, March 11, 2004 7:04 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: Oracle Performance
 
 
 
¿Is it normal that a SQL sentence: MAX or MIN, execute over 1.5 minutes on
Oracle 9i, and in 1 sec. on SQL Server 7.0 (2 millions of registers), using
equals data structures and servers? ¿Why occur this situation?
 
 
 
Thank you,
 
 
 
Huascar Espinoza
 
 
 
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