| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Mailing Lists -> Oracle-L -> RE: how to improve sequential scans ?
Rahul,
Some various thoughts:
What about using outlines to change the SQL execution plan - you could do this without touching the execution plans.
What about splitting the tablespace that the table is in across multiple datafiles and provided the table is in multiple extents it then should split across multiple disks - there are some articles on Ixora referring to this. Kind of a poor-persons partitioning if you don't own a partitioning license.
Regards,
Bruce Reardon
-----Original Message-----
Sent: Tuesday, 17 July 2001 11:26
Rahul,
Could this table be partitioned and the partitions spread across multiple disks? Could the index be partitioned as well? The concept here is, of course, "divide and conquer".
Could a column or two (or three) be added to the index to satisfy the query without having to hit the table?
How frequently are these literal queries being issued? Are they shredding your shared pool and chewing up CPU by making Oracle do extra work in shared pool memory management?
Are there aggregation (vs aggravation <g>) functions or order bys in the queries that might be causing sorts to disk? If aggregation, could you use materialized views to satisfy the queries?
....just a few ideas.
Jack
-----Original Message-----
Sent: Tuesday, July 17, 2001 7:36 AM
list (AIX, 7.3.2)
5 clients are shooting the same sql to read data from an 18 million rows
table.
each time the sql uses a different literal value in the where clause... no
bind variables.
I CANNOT TOUCH THE APPLICATION, and have been given the task to re-configure
the
DB to increase performance.
i have moved the table and it;s associated index to separate disks. and
iostat show that
only that only those two disks are being read.
the session wait show that all the times the sessions are waiting on "db file sequential read"
the db file being sequentially read in the above sessiion is the TABLE from
which
all the sid's are reading
the table is analyzed and the sql's issued use the index.
how can i further tune this config. ?
TIA Rahul
PS: my next step is to put the files on raw disks.
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Reardon, Bruce (CALBBAY) INET: Bruce.Reardon_at_comalco.riotinto.com.au Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-LReceived on Tue Jul 17 2001 - 17:46:26 CDT
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
 |
 |