Re: Please Help: table locking

From: Frank <franjoe_at_frisurf.no>
Date: Sat, 16 Dec 2000 08:20:25 +0100
Message-ID: <EME_5.819$Fh4.19909@news1.oke.nextra.no>

<susana73_at_hotmail.com> wrote in message news:9142a6$ebk$1_at_nnrp1.deja.com...
> In article <913tjl$aks$1_at_nnrp1.deja.com>,
> Mike Krolewski <mkrolewski_at_rosetta.org> wrote:
> > In article <913s5g$9dm$1_at_nnrp1.deja.com>,
> > susana73_at_hotmail.com wrote:
> > > I have an app that open 2 database connections concurrently. It hangs
> > > couple times a week due to table lock. The following is a report
 shows
> > > what happen:
> > >
> > > USERNAME SID SERIAL# TY HELD REQUEST
> > > ------------------------------------------------------------
> > > SQL
> > > ------------------------------------------------------------
> > > PROD_USER 13 124 TX Exclusive None
> > > UPDATE object set flag = 1 WHERE plan = 'A' AND Id = 3466629
> > >
> > > PROD_USER 29 9034 TX None Share
> > > UPDATE object set flag = 1 WHERE plan = 'B' AND Id = 3466631;
> > >
> > > The two sessions(SID 13,29) are updating different rows so I have no
> > > idea how this can generate locks. Session 13 is held as EXCLUSIVE and
> > > Session 29 are requesting as SHARE. What does that mean and would
 this
> > > be a hint to solve this problem?
> > >
> > > I do not specify any locking feature explicitly in my application at
> > > all.
> > >
> > > Please Help!! Thanks.
> > >
> > > Susan
> > >
> > > Sent via Deja.com http://www.deja.com/
> > > Before you buy.
> > >
> >
> > Needs more information. It is unlikely that based on the above
> > statements and no other users on-line that the database will hang.
> > How big are the tables (rows/extents/tablespace)? Are there any
> > indexes? Are there any ohter users on line? If you openned two
> > connectinos and executed the above statements with no there users, the
> > system hangs? Or does it just take alot of time?
> >
> > --
> > Michael Krolewski
> > Rosetta Inpharmatics
> > mkrolewski_at_rosetta.org
> > Ususual disclaimers

>

> There are 800k rows. Tablespace is 20GB. Extents of the 'object' table
> is 2000 extents(i know this is not optimized and I'll fix this later).
> There is a combined PK on object(id,plan). There are no other users on
> line. To update one row should take a second, so I am sure it hangs.

>

> Thanks!

>

> Susan

>
>

> Sent via Deja.com http://www.deja.com/
> Before you buy.

Hi!

1.Are there any triggers on this table (or one of its detail-tables)? Perhaps a triggerlogic hits
a unfortunate branch in some if-construction somewhere, that runs a long time/forever..

2.Perhaps if your update/logic is a part of a distributed transaction there may be a lock in a remote database?
Having two concurrent sessions from the same application may cause two concurrent transactions in remote
databases too.

Frank Received on Sat Dec 16 2000 - 01:20:25 CST