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Interaction between Cursor and Transaction storage? 3+ messages / 2 participants [nested] [flat]
* Interaction between Cursor and Transaction storage? @ 2003-03-22 21:40 William West <wwest@csc.com> 0 siblings, 0 replies; 3+ messages in thread From: William West @ 2003-03-22 21:40 UTC (permalink / raw) To: pgsql-interfaces Could someone please clarify how Cursor storage and uncommitted Transaction storage interact with each other? We are using the ECPG interface to 7.2.1 on RedHat Linux 7.2, to whatever extent that affects the answer to this set of questions. .... OUR APPLICATIONS [RW-APP: Read-Write Application] There is an always-running Application Process with a fe-be session performing inserts and updates [RO-APP: Read-Only Application] There is another infrequently started Application Process that every once in awhile makes another fe-be session. This Application scans through the DB by opening Cursors on various parts of the DB, fetching from the Cursors, closing the Cursors, then closing its fe-be session and exiting. ..... It is our understanding that Transactions will see to it that RO-APP Cursor opens will see only whatever RW-APP most recently committed prior to the time RO-APP opens its Cursor, because uncommitted RW-APP Transactions are held in session-specific storage pending RW-APP performing a commit or a rollback. The design of RO-APP expects and allows for this. ...... Our questions come from the fact that it is unclear to us just exactly how open Cursor storage interacts with uncommitted Transaction storage? QUESTION 1: Should RO-APP be doing anything other than closing the Cursors, to tell the Engine to just 'cleanup' when RO-APP is about to close its fe-be session and exit? QUESTION 2: Will an attempt by the RW-APP to do a commit or rollback while the RO-APP is fetching through an open Cursor cause RW-APP to wait until RO-APP closes the Cursor? QUESTION 3: Will an attempt by the RO-APP to open a Cursor while the RW-APP is performing a commit or rollback cause RO-APP to wait until RW-APP finishes its commit/ rollback? .... Thanks for reading such a long question. ^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Interaction between Cursor and Transaction storage? @ 2003-03-25 14:00 Christoph Haller <ch@rodos.fzk.de> 0 siblings, 0 replies; 3+ messages in thread From: Christoph Haller @ 2003-03-25 14:00 UTC (permalink / raw) To: pgsql-interfaces; +Cc: wwest@csc.com > > QUESTION 1: > > Should RO-APP be doing anything other than closing > the Cursors, to tell the Engine to just 'cleanup' when > RO-APP is about to close its fe-be session and exit? NO. > > QUESTION 2: > > Will an attempt by the RW-APP to do a commit or rollback > while the RO-APP is fetching through an open Cursor cause > RW-APP to wait until RO-APP closes the Cursor? NO. > > QUESTION 3: > > Will an attempt by the RO-APP to open a Cursor while > the RW-APP is performing a commit or rollback cause > RO-APP to wait until RW-APP finishes its commit/ > rollback? NO. > The answers are given to my best knowledge. If you prefer to be absolutely sure you should post your questions to the hackers list, as you've received no reply on this list within three days. Regards, Christoph ^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Interaction between Cursor and Transaction storage? @ 2003-03-25 15:19 William West <wwest@csc.com> 0 siblings, 0 replies; 3+ messages in thread From: William West @ 2003-03-25 15:19 UTC (permalink / raw) To: pgsql-interfaces; +Cc: Christoph Haller <ch@rodos.fzk.de> Thanks, Christoph. Those were the answers I wanted. ^ permalink raw reply [nested|flat] 3+ messages in thread
end of thread, other threads:[~2003-03-25 15:19 UTC | newest] Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2003-03-22 21:40 Interaction between Cursor and Transaction storage? William West <wwest@csc.com> 2003-03-25 14:00 Re: Interaction between Cursor and Transaction storage? Christoph Haller <ch@rodos.fzk.de> 2003-03-25 15:19 Re: Interaction between Cursor and Transaction storage? William West <wwest@csc.com>
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