Re: Number of Transaction Slots

You've already got the main answer from KG and RF.

The figures on Metalink look much too high - but they might be from an earlier version of Oracle. The size is strongly version dependent.

In Oracle 9 (automatic UNDO only) the figures are closer to:

    4K        => 22
    8K        => 48

In manual rollback, viz Oracle 8
    4K        => 47 (or maybe 48)

Roughly speaking each time you double the block size you double and add a few for the number of slots.

To dump a rollback header segment block, the easy option is:

    alter system dump undo header "segment name";

The "" are a necessity for automatic undo headers in Oracle 9 because their names start with an underscore; they are optional for manual rollback segments

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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-----Original Message-----
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> Date: 07 March 2002 20:21

|I believe someone else had asked this question before, but I did not
see a
|reply. Does anyone know the number of transaction slots in the
rollback
|segment header for block sizes of 4k, 8k, et all?
|
|From what I have read, for a block size of 2K, its 21 transaction
slots.
|(Steve Adams at www.ixora.com.au)
|For a block size of 8K, its 98 (Jonathan Lewis on Metalink - For
8.1.6)
|
|As per Metalink:
|
|2K - 31
|4K - 67
|8K - 140
|
|Different answers? What does it depend on? OS Version, Oracle
Version,
|number of extents in rollback segment??

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