RE: Row cache lock wait issue in RAC
- From: "Luca Canali" <Luca.Canali@xxxxxxx>
- To: "Anand Rao" <panandrao@xxxxxxxxx>
- Date: Thu, 1 Jun 2006 11:31:44 +0200
Hi Anand,
I am using Oracle 10.2.0.2 with RAC (6 nodes ) + ASM on RHEL 3. I use
LMT bigfile tablespaces and ASSM. I am aware of the exchange partition
bug, but my case looks different: I don't seem to have any deadlocks and
using the workaround you mention (fixed quotas) did not help.
Cheers,
L.
________________________________
From: Anand Rao [mailto:panandrao@xxxxxxxxx]
Sent: Thursday, June 01, 2006 11:15 AM
To: Luca Canali
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: Row cache lock wait issue in RAC
Luca,
In LMT, Oracle acquired a row cache enqueue on dc_tablespace_quotas
after a segment is built. this could even be a partition exchange or
add. In DMT, it used to be worse, where Oracle acquired this enqueue to
check quotas and add extents.
The quota checks are still performed but only at the end, even though
you may have provided unlimited quota. i think Dimitre's suggestion to
provide fixed quota came from this aspect. so, we both assume you are
using LMT :)
also, are you using partitions and dynamically exchanging data to
partitions? if so, run the EXCHANGE PARTITION statements serially and
ensure it involves a single tablespace.
one bug hit suggested providing the quotas in M or K instead of bytes,
especially if the quota is more than 4GB.
unfortunately, you are hitting a couple of bugs related to this enqueue
especially while Oracle updates TSQ$ table...problem occuring mainly in
high insert RAC environments.
you didn't mention the version. depending on yours, you can get a
backport fix. some fixes are available in 10.1...but there are a couple
of bugs in 10.1 too :(
hope that helps
cheers
anand
On 01/06/06, Radoulov, Dimitre <cichomitiko@xxxxxxxxx> wrote:
> By the way, I would be quite interested to know why oracle
needs to
> acquire row cache lock on dc_tablespace_quotas in this case
and if there
> is any way to skip this operation with 'a clever hack'.
If you search on MetaLink with keyword "dc_tablespace_quotas"
(with bug
database search enabled), there are a few bugs related to data
dictionary
cache deadlocks.
Regards
Dimitre
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