Re: Row cache lock wait issue in RAC
- From: "Anand Rao" <panandrao@xxxxxxxxx>
- To: "Luca Canali" <Luca.Canali@xxxxxxx>
- Date: Thu, 1 Jun 2006 14:45:20 +0530
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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