Re: what's the internal transaction table for....
From: The Boss <usenet_at_No.Spam.Please.invalid>
Date: Mon, 8 Feb 2010 23:40:16 +0100
Message-ID: <4b7092d1$0$27088$e4fe514c_at_dreader27.news.xs4all.nl>
Mark D Powell wrote:
> On Feb 8, 2:53 pm, Ken Quirici <kquir..._at_yahoo.com> wrote:
>> The 10g discussion of transaction commitment has this:
>>
>> The internal transaction table for the associated undo tablespace
>> that the transaction has committed, and the corresponding unique
>> system change number (SCN) of the transaction is assigned and
>> recorded in the table.
>>
>> which the 11g manual corrects to:
>>
>> The internal transaction table for the associated undo tablespace
>> RECORDS [my uppercase] that the transaction has committed, etc.
>>
>> What is this internal transaction table? I can't find reference to it
>> anywhere else. It seems as though it
>> would be important in deciding how long to keep rollback segments
>> around, but I could be wrong there,
>> since they seem to be kept around forever, or until they get
>> overwritten, whichever comes first.
>>
>> Thanks for any illumination!
>
> I believe that the material is referring to the Interested Transaction
> List, ITL, stored in each table block to keep track of changes by
> pointing to the undo segment that contains the undo for the
> transaction. The table parameter initrans controls how many of these
> areas are pre-allocated to the blocks. Each ITL is 23 bytes in length
> plus I believe the ITL is preceeded by a length or usage byte so the
> cost is 24 bytes each space wise.
>
> Jonathan Lewis has written in detail on Oracle usage of the ITL. You
> can find his web site via a search.
> You can see the ITL in a block dump.
>
> HTH -- Mark D Powell --
Date: Mon, 8 Feb 2010 23:40:16 +0100
Message-ID: <4b7092d1$0$27088$e4fe514c_at_dreader27.news.xs4all.nl>
Mark D Powell wrote:
> On Feb 8, 2:53 pm, Ken Quirici <kquir..._at_yahoo.com> wrote:
>> The 10g discussion of transaction commitment has this:
>>
>> The internal transaction table for the associated undo tablespace
>> that the transaction has committed, and the corresponding unique
>> system change number (SCN) of the transaction is assigned and
>> recorded in the table.
>>
>> which the 11g manual corrects to:
>>
>> The internal transaction table for the associated undo tablespace
>> RECORDS [my uppercase] that the transaction has committed, etc.
>>
>> What is this internal transaction table? I can't find reference to it
>> anywhere else. It seems as though it
>> would be important in deciding how long to keep rollback segments
>> around, but I could be wrong there,
>> since they seem to be kept around forever, or until they get
>> overwritten, whichever comes first.
>>
>> Thanks for any illumination!
>
> I believe that the material is referring to the Interested Transaction
> List, ITL, stored in each table block to keep track of changes by
> pointing to the undo segment that contains the undo for the
> transaction. The table parameter initrans controls how many of these
> areas are pre-allocated to the blocks. Each ITL is 23 bytes in length
> plus I believe the ITL is preceeded by a length or usage byte so the
> cost is 24 bytes each space wise.
>
> Jonathan Lewis has written in detail on Oracle usage of the ITL. You
> can find his web site via a search.
> You can see the ITL in a block dump.
>
> HTH -- Mark D Powell --
Are you sure it is not referring to X$KTUXE ?
-- JeroenReceived on Mon Feb 08 2010 - 16:40:16 CST