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Home -> Community -> Mailing Lists -> Oracle-L -> RE: To IOT or not
While evaluating the use of IOT for over db, i came across some points:
--IOTs will use cost based optimization, even in rule environment.
--IOTs are faster than normal tables when queries are based on the primary key.
--Secondary indexes on IOTs may not perform as well as they are based on logical rowids and optionally uses a guessing method, you may need to periodically rebuild.
since we user rbo, IOTs were opted out.
rgds
amar
-----Original Message-----
From: paquette stephane [mailto:stephane_paquette_at_yahoo.com]
Sent: Tuesday, June 26, 2001 1:24 PM
To: Multiple recipients of list ORACLE-L
Subject: To IOT or not
Hi all,
Vacation is over !
We'll have some tables with a PK and between 1 and 3
other fields . Those tables will be insert once and
read 2 to 7 times.
I'm wandering about the use of IOT and done some
tests.
When inserting 700 000 rows, the IOT and the standard table with a PK took the same time .
When reading by querying on the PK in a loop (looping 700 000 times) I have the same total query time but the IOT is reading 1 300 000 blocks and spending more time in the execute phase than in the fetching phase, the standard table with PK is reading 2 000 000 blocks and spending just a little bit more time in the executing phase than the fetching phase.
Those tables may not benefit from a lot of caching since there are in the staging area of a DW system.
Any advices or bad experience on IOT (Oracle 816, DW system) ?
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Liststo: 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). Received on Tue Jun 26 2001 - 06:14:47 CDT
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