RE: can clustering help INSERTS ?

Stephane

   You mentioned "each additional index costs about 2.5 times the cost of inserting into a non-indexed table". I just wanted to point out that Kevin Loney has done some performance tests involving the number of indexes. I don't know if he has published these anywhere. In a nutshell, the results were that a single index really hurts insert performance, and each additional index increases the hurt, but by a decreasing amount. The conclusions were:

• If you can drop all indexes, that will really help inserts.
• If you have one index, adding a second index will really hurt, but not as bad.
• If the table already has 15 indexes, adding one more index probably won't be noticed.

Dennis Williams
DBA, 40%OCP
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Friday, October 25, 2002 8:04 AM
To: Multiple recipients of list ORACLE-L

Rahul wrote:
>
> List,
> i have two heavily inserted tables, the structures are same.
> currently these tables reside on separate disks, can i increase the
> performance
> of inserts if i create these tables in a cluster ? as a cluster would
force
> the rows of both the tables
> to be physically close on the disk !
>
> regards
> -rahul
>
> Ora 7.3 on AIX
>

You would also increase contention ... I'd rather try to augment the number of free lists, and, if you are lucky enough not to access your indexes in RANGE SCAN mode, to create them as REVERSE. Beware of indexes, by the way, each additional index costs about 2.5 times the cost of inserting into a non-indexed table (in terms of logical blocks).

-- 
Regards,

Stephane Faroult
Oriole Software
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Stephane Faroult
  INET: sfaroult_at_oriole.com

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
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-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: DENNIS WILLIAMS
  INET: DWILLIAMS_at_LIFETOUCH.COM

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
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-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).