Enqueue TX level 4 wait -- blocks dump
- From: "Diego Cutrone" <diegocutrone@xxxxxxxxxxxx>
- To: "Oracle List" <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 3 May 2004 13:35:17 -0700
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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