RE: Remote Select opening transaction

From: Powell, Mark D <mark.powell_at_eds.com>
Date: Tue, 3 Apr 2007 10:06:33 -0400
Message-ID: <D1DC33E67722D54A93F05F702C99E2A9B42A65@usahm208.amer.corp.eds.com>

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 execution?

 http://www.jlcomp.demon.co.uk/faq/dblink_commit.html <http://www.jlcomp.demon.co.uk/faq/dblink_commit.html>  

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

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        From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Marc Demlenne

	Sent: Tuesday, April 03, 2007 8:43 AM
	To: Kerber, Andrew W.
	Cc: oracle-l_at_freelists.org
	Subject: Re: Remote Select opening transaction
	
	
	Hi, 
	
	It is ! You can try the following : 


	- Do a select * from remoteDB.remoteTable_at_remoteHost (but

remoteDB is enought, can be same host)


	- Don't commit, rollback or quit. Be carefull not to exit in

timeout 


	- 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 rn.name, 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(+) =

rn.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_at_umb.com> 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_at_freelists.org [mailto:

oracle-l-bounce_at_freelists.org <mailto:oracle-l-bounce_at_freelists.org> ] On Behalf Of Marc Demlenne

		Sent: Tuesday, April 03, 2007 7:08 AM
		To: oracle-l_at_freelists.org
		Subject: Remote Select opening transaction

		 

		Hello, 
		
		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,                 

		-- 
		Marc 

	
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	-- 
	Marc Demlenne 

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Received on Tue Apr 03 2007 - 09:06:33 CDT