RE: Remote Select opening transaction

  • From: "Powell, Mark D" <mark.powell@xxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 3 Apr 2007 10:06:33 -0400

For a demo on this topic you can see the following:


Why does it seem that a select over a db link requires a commit after


-- Mark D Powell -- 
Phone (313) 592-5148 



        From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Marc Demlenne
        Sent: Tuesday, April 03, 2007 8:43 AM
        To: Kerber, Andrew W.
        Cc: oracle-l@xxxxxxxxxxxxx
        Subject: Re: Remote Select opening transaction
        It is ! You can try the following : 
        - Do a select * from remoteDB.remoteTable@remoteHost (but
remoteDB is enought, can be same host)
        - Don't commit, rollback or quit. Be carefull not to exit in
        - And monitor the RBS. you'll notice that your sqlplus process
is locking one of the RBS, and the number of extent will start growing
up and up until you'll recah the ORA-01562 error. 
        I use : 
        select, r.curext, t.start_uext, r.extents, t.xidusn,
s.sid, s.process, t.start_time
        from V$rollstat r,  v$rollname rn, V$transaction t, v$session S
        WHERE t.addr = s.taddr (+) and t.XIDUSN=r.USN AND r.usn(+) =
        Exiting your sqlplus (or commit or rollback) will unblock the
situation, freeing your RBS. In my case, we use the "OPTIMAL" parameter
and see the number of extents immediately reducing to it's optimal value
        Best Regards, 
        On 4/3/07, Kerber, Andrew W. <Andrew.Kerber@xxxxxxx> wrote: 

                Hi.  I am pretty sure your information is incorrect.  I
have never seen a select across a db link open a transaction.


                -----Original Message-----
                From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:
oracle-l-bounce@xxxxxxxxxxxxx <mailto:oracle-l-bounce@xxxxxxxxxxxxx> ]
On Behalf Of Marc Demlenne
                Sent: Tuesday, April 03, 2007 7:08 AM
                To: oracle-l@xxxxxxxxxxxxx
                Subject: Remote Select opening transaction


                In Oracle 8, when performing a select query on another
database threw DB link, Oracle opens a transaction that could only be
closed by commit or rollback. That could be harmful when developers are
not aware of this and don't close transaction. (leading to ORA-01562.) 
                What is the reason of this behaviour ? Is there some
docs / faq explaining this ? 
                Is this feature also common to later versions of Oracle
                Thanks a lot for any piece of information given,

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