RE: Locally managed tablespaces

Hi All,

I was working on a tuning assignment last week where one of the more minor changes made was to migrate their "scratch" tablespace to locally managed. The gain from that change was about 2%. That saving was due to the elimination of ST enqueue contention associated with multiple processes trying to create scratch tables at the same time.

It is only certain data dictionary queries that are slower with locally managed tablespaces, and that's only really bad if you have too many extents per segment. See http://www.ixora.com.au/tips/creation/extents.htm for why. The performance of SELECT and DML statements against user data is unchanged. The performance of space management transactions is slightly improved, and greatly if ST enqueue contention was otherwise a problem.

@   Regards,
@   Steve Adams
@   http://www.ixora.com.au/
@   http://www.christianity.net.au/

-----Original Message-----
Sent: Wednesday, 31 January 2001 5:11
To: Multiple recipients of list ORACLE-L

Has anyone taken a PROD DB and changed it to using LMTSs and then noticed a perf change + or -?

---

TheOracleDBA
theoracledba_at_lycos.com



On Tue, 30 Jan 2001 10:30:29
 Bunyamin K.Karadeniz wrote:


>  But some had claimed  that  Locally managed tablespaces are slower. I do

>not know if it is correct  but you must consider it .

> And I wonder the performance results too.

>

>----- Original Message -----

>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>

>Sent: Tuesday, January 30, 2001 3:35 PM

>

>

>> I have always been concerned with fragmentation of tablespaces, whether it

>> be lots of extents, honeycomb or

>> bubble fragmentation. Now I am reading that in Oracle 8i with the use of

>> locally-managed table spaces,

>> these concerns are a thing of the past as Oracle now uses bit maps within

>> the tablespaces themselves to

>> do space management. This seems foreign to me that even though Oracle will

>> use up all the space in

>> the tablespaces with no coalescing,  it is OK that extents will go into

>the

>> thousands with no performance degradation.

>> Could folks who are currently using locally managed tablespaces please

>> comment on how well it

>> is working for them and if they have experienced any problems in using

>them.

>> Thanks

>> Skip


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Author: Steve Adams
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