RE: Enqueue TX level 4 wait -- blocks dump
- From: "Cary Millsap" <cary.millsap@xxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 3 May 2004 00:36:25 -0500
Is it an insert of a row whose key value is the same as the key value of
some other uncommitted insert?
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
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-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Diego Cutrone
Sent: Monday, May 03, 2004 3:35 PM
To: Oracle List
Subject: Enqueue TX level 4 wait -- blocks dump
Hi everybody,
I have a question on TX enqueues.
I'm seeing a lot of TX enqueues level 4 on a table. I have also found
that the statement that was waiting on this wait was an ***INSERT***
operation.
Oracle 8i
Table:
ITL = 10
4 FREELISTS
4 FREELISTS GROUPS
PCTFREE 20
I dumped every table block and checked the ITC entry. I found ITC was
almost always 10 for every block.
Then I checked for the average free space within the blocks, (supposing
the block had needed an additional ITL slot) and again I found that in
every block there was at least 80 bytes free. (as Avsp reported).
So I went for the indexes
ITL = 11
4 FREELISTS
4 FREELISTS GROUPS
PCTFREE 10
and I found no problem at all in the ITC entries.(most of them were 11)
But I found many blocks with kdxcoavs = 0. (no free space on them).
Taking into consideration that we're talking about an INSERT,
Can it be possible that the TX 4 is being caused by an ITL shortage in
the index?
(All slots are being used and there's no free space in the block, so
when a new INSERT needs to put its entry in that block, despite of the
fact that this block will surely need to split because there's no free
space left in it, the transaction first needs to get a free ITL slot and
as they are all taken and there's no free space it has to wait in a
enqueue TX 4. Is this the way it works on this case?)
What do you think?
Thanks,
Diego.
PS: (I still have to check one last index, but I believe I will find the
same I have just found so far)
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