RE: Automatic Segment Space Management

In a very limited tests that I performed with ASSM (quite some time ago), I found that it tends to use a bit more space than non-ASSM. Something to keep in mind when FTS is used to access tables. Not sure if this changed in 9.2.0.2.x.

• Kirti

-----Original Message-----
Sent: Wednesday, February 19, 2003 10:24 AM To: Multiple recipients of list ORACLE-L

Jay,

I have been using ASSM for last five months in our Datawarehouse environment. Haven't had a chance to play with the OLTP side, yet.

Inserts are way faster as compared to system managed extent allocation. I read Don's article on DBAZINE. However, I would like to add one caveat here: ASSM does not *eliminate* buffer busy waits as the article claims; it *reduces* them. BBW occur due to concurrent access to a buffer by more than one session. This will be the case regardless of number of freelists. While ASSM eliminates the freelist contention - thereby reducing BBW in inserts - it does not reduce the likelihood that more than one sessions will try to get the same block to the buffer cache simulataneously.

Table drops appear a little slower in ASSM; but that could be wrong - I never timed dropping a table in the system managed mode.

HTH. Arup Nanda

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, February 19, 2003 9:33 AM

> I'm continuing to introduce myself to 9i. I've been reading about
Automatic Segment Space Management, and I just wondered if anybody had any positive/negative experiences with it. I got some good info at:
>
> http://www.dbazine.com/burleson11.html
>
>
> Thank you,
>
>
> Jay Hostetter
> Oracle DBA
> D. & E. Communications
> Ephrata, PA USA
>

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