Oracle-L: RE: Autoallocate (was Re: LMT monitoring)

From: <Jared.Still_at_radisys.com>
Date: Mon, 17 Mar 2003 09:59:17 -0800
Message-ID: <F001.0056BD73.20030317095917@fatcity.com>

IME the 'trouble' of managing rollback segments is grossly exaggerated. They rarely cause me any trouble.

Only errant programmers cause me problems.

Jared

DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM> Sent by: root_at_fatcity.com
03/17/2003 06:28 AM
Please respond to ORACLE-L

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        Subject:        RE: Autoallocate (was Re: LMT monitoring)

Alex

If you do not specify the UNDO TABLESPACE when creating the database then
AUTOEXTEND is set to ON. I was able to alter that to OFF.

The point of the UNDO is that it is automatically managed by Oracle. If you can't cope with that, or you decide that doesn't work well for you, then
you can revert to the old manual ROLLBACK segments. I think that few sites had their rollback segments properly configured, and Oracle has been criticized for requiring a lot of expert attention compared to other databases. This is Oracle's attempt to reduce the TCO (Total Cost of Ownership).

Dennis Williams
DBA, 40%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Sunday, March 16, 2003 10:59 PM
To: Multiple recipients of list ORACLE-L

How about UNDO tablespace in 9.2?
It gets created with "autoallocate", and there is no way to change it or specify any parameters for undo segments. Each segment extended as needed, and when shrinked deallocated some extents
not necessary the last, than allocate new extent.

Alex.

Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, March 12, 2003 2:22 PM

You do get odd results. The last time I tested on a clean tablespace, an initial of 65MB gave me a consistent result which I recall as:

    Extent 0             at 8MB
    Extents 1 - 56     at 1MB each
    Extent 57            at 8MB

Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Tuesday, March 11, 2003 6:23 AM

case

     when initial_extent < 1m then
       case when extents < 16 then next = 64k,
            when extents < 80 then next = 1m,
            when extents < 200 then next = 8m,
            else next = 64m
     when initial_extent >= 1m then
       case when extents < 64 then next = 1m,
            when extents < 184 then next = 8m,
            else next = 64m )

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Author: Alex Feinstein
INET: alexf1_at_san.rr.com

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Author: DENNIS WILLIAMS
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INET: Jared.Still_at_radisys.com

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