RE: No Rows Deadlock and PCTFREE, INITRANS on 8.1.7.2

It does not look like an inittrans problem on the table. I remember reading that Oracle will try to avoid contention on itl if it's doing insert by adding new blocks to the free lists. The only conflict that could happen on itl (inittrans) during inserts is for indexes.

Could you have a primary key constraint that has some SYS_<..> index associated with it and was forgotten to be dropped?

Regards,

Waleed

-----Original Message-----
Sent: Thursday, April 25, 2002 3:04 PM
To: Multiple recipients of list ORACLE-L

Waleed,

There used to be a single process that loaded the data. It ran too long and the application owners split the job out into two process. One started at one end and loaded data in ascending order and the other started at the other end and loaded in descending order.

Both jobs run at the same time in the same database. They've run like this for a couple of years in the current 8.0.4 database without any obvious locking errors.

Cherie Machler  

                    "Khedr,

                    Waleed"              To:     Multiple recipients of list
ORACLE-L <ORACLE-L_at_fatcity.com>       
                    <Waleed.Khedr@       cc:

                    FMR.COM>             Subject:     RE: No Rows Deadlock
and PCTFREE, INITRANS on 8.1.7.2        
                    Sent by:

                    root_at_fatcity.c

                    om

 

 

                    04/25/02 01:33

                    PM

                    Please respond

                    to ORACLE-L

 

 

Can you please give more details on: While testing our nightly load job that
runs in two simultaneous
streams (ascending and descending).

What do you mean by descending and ascending (simultaneous)?

Thanks

Waleed

-----Original Message-----
Sent: Thursday, April 25, 2002 11:19 AM
To: Multiple recipients of list ORACLE-L

We are testing an upgrade of our warehouse from 8.0.4 to 8.1.7.2.

While testing our nightly load job that runs in two simultaneous streams (ascending and descending), we have been getting deadlock errors. The trace file shows the the rows waited on are no rows.

In response to a TAR I opened with Oracle, Oracle responded that the application needs to be rewritten so that there is only a single stream. However our developers aren't inclined to do so because our nightly window isn't long enough for a single job and because this application worked fine as is on 8.0.4.

Our developers have discovered an old article (perhaps from 7.3.4 times) by Roger Snowdent "The Deadly Embrace (Oracle Locking Strategies)" www.dbdomain.com/120197.htm
that indicates this deadlock error with no rows is an indication of an "insidious table".

The article states that the the INITRANS and PCTFREE parameters may be set too low for the table in use.

Has anyone encountered this deadlock with norows indicated error before? If yes, how did you resolve it?

In our current 8.0.4 datawarehouse database, this partitioned table has PCTFREE of 10 and INI_TRANS of 1. The block size is 8k, we are using Sun Solaris 2.6 and Veritas Volume Manager. As I said, we are preparing to upgrade this to 8.1.7.

What would be an appropriate setting for PCTFREE and INI_TRANS for this large warehouse partitioned table in these circumstances?

What are our options if we want to change the PCTFREE and INI_TRANS for new data that gets loaded? Can we change PCTFREE and INI_TRANS and then just keep loading more data into an existing partition? Can we change these values in new partitions and leave them the same in existing partitions? What would be the drawbacks of having some partitions
with one value for these storage parameters and other partitions with different
values?

Also, the developers want to know if there is any utility that could be run to
determine whether other tables might be susceptible to this deadlock condition.
Something like dbverify or analyze with some validation option?

Thanks in advance for your feedback.

Cherie Machler
Oracle DBA
Gelco Information Network

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