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Home -> Community -> Mailing Lists -> Oracle-L -> RE: INSERT versus CTAS
Hi Gorbachev
You said :
I want to change INSERT to CTAS, but it requires some efforts to amend the script. I assume that CTAS would be > more performant for IOT since it will create index as temporary segment in table's tablespace and then just amend dictionary (object definition + hwm). So I expect to eleminate UNDO generation, reduce temporary space requirements, reduce redo, and.... well, boost performance.
ITEM_SET_ID , LOCATION_ID , PERIOD_ID , SEGMENT_TYPE , RCPT_AMT , RCPT_UNITS , SLS_AMT , SLS_UNITS ,
alter table item_location_periods_tbl
exchange partition ITEM_LOC_PER_SEG_1 with table ilp_seg_1
including indexes
with validation
/
8.1.7.4 64 bit + one-off patch for compressed index bug, in Sun 2.8
Thanks
Riyaj "Re-yas" Shamsudeen
Certified Oracle DBA
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Alexander Gorbachev
Sent: Saturday, December 11, 2004 9:41 AM
To: ORACLE-L
Subject: INSERT versus CTAS
Hi,
What are the differencies between "create ... table as select" and
"create table" + "insert /*+ parallel(...) append(...) */ into" from
performance point of view? I am interested in various tables:
- non-partitioned
Currently, I use create + insert with parallel append hints. It works
reasonable fast for us - we are able to fill 100+ Gb of data within 1,5
hour. However, inserting in partitioned IOT's is quite different. There
are few problems:
- slow
We are able to overcome some problems iterating through each partition, but it's not a clean solution and performance is still far from what we target.
I want to change INSERT to CTAS, but it requires some efforts to amend the script. I assume that CTAS would be more performant for IOT since it will create index as temporary segment in table's tablespace and then just amend dictionary (object definition + hwm). So I expect to eleminate UNDO generation, reduce temporary space requirements, reduce redo, and.... well, boost performance.
Any comments/links are appreciated.
It's 9.2.0.5 on 64 bit HP-UX.
Thanks in advance.
Alex
-- Best regards, Alex Gorbachev -- http://www.freelists.org/webpage/oracle-l -- Attached file included as plaintext by Ecartis -- -- Desc: Signature The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. If the reader of this message is not the intended recipient, you are hereby notified that your access is unauthorized, and any review, dissemination, distribution or copying of this message including any attachments is strictly prohibited. If you are not the intended recipient, please contact the sender and delete the material from any computer. -- http://www.freelists.org/webpage/oracle-lReceived on Sat Dec 11 2004 - 11:58:00 CST
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