Re: DX Lock problem

On Jun 29, 6:37 am, sorc...@xxxxxxxxx wrote:
On Jun 28, 6:13 pm, Charles Hooper <hooperc2...@xxxxxxxxx> wrote:
On Jun 28, 10:48 am, sorc...@xxxxxxxxx wrote:

Google search:
oracle dx lock
or
oracle dx lock commit rollback

Finds this page:
http://www.jlcomp.demon.co.uk/faq/find_dist.html

Charles Hooper
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc.

Charles,

that was clear to me... what is not clear is that I
can't see the point of acquiring an exclusive lock on an
object (whatever the object is, I smell it might be an
undo segment) in exclusive mode and serializing all other
session.
The symptom is evident in production: once in a while we see
this exclusive mode lock of type DX, the database slows down
and every single query (select i mean) not necessarly issued
from an xa connection against, for example, the gv$global_transaction
is there forever.
I am pretty sure is a bug... but I need to reproduce it somehow.

Yes, the distributed_lock_timeout is exactly 9000, as Mladen
suggested me, but i can't even force commit or rollback of that
in doubt transaction because I can't select from dba_pending_trans.

g

I will have to defer this question to someone who uses distributed
transactions more frequently than I. I recall seeing similar DX locks
when I experimented with queries in remote databases. Sessions would
occasionally hang for no apparent reason. It seems like ghost
sessions would also remain connected to the database, long after the
calling session was terminated. At the time I located the above
article that indicated a COMMIT or ROLLBACK was needed following a
SELECT to clear the lock, and it seemed to make perfect sense.

You might want to check the first two links on this search page:
http://groups.google.com/groups?um=1&tab=wg&hl=en&q=oracle%20dx%20lock%20lewis

Mladen, thanks for the parameter hint.

Charles Hooper
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc.

.

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