Re: Receiver Save & Rolled back entries

["Dan_boggs" <boggsdan@xxxxxxxxxxxxxxxx>]

Ahhh...  A topic I'm familiar with.  :-)

When journal entries are rolled back, NEW entries are written to the journal
receiver.  These entries basically are the reverse of what the original
entries were, and in reverse order.  So, if two adds were followed by three
updates, the reversing entries would be three more updates followed by two
deletes.

In the case of recovery purposes, the system will still process the entries
in the journal, including those rolled back.  It would be nice if it skipped
them, yet some people tend to have very long or open commit cycles, even
some spanning multiple receivers.  The only drawback to using journals for
recovery is what it doesn't do.  And those are basically file level
functions such as moves, renames, reorgs, and the like.  In cases like that
processing of receivers for recovery stops.  You must then manually perform
the additional tasks and restart recovery where it left off.

Hope this helps, and if my memory is still intact.

Daniel R. Boggs
Manager, Software Development

Lakeview Technology Inc.
2301 W. 22nd Street
Suite 206
Oak Brook, IL  60523

(630) 586-8806
(630) 573-0015 FAX
-----Original Message-----
From: Gord Hutchinson <ghutchinson@tstoverland.com>
To: MIDRANGE-L@midrange.com <MIDRANGE-L@midrange.com>
Date: Thursday, December 10, 1998 2:37 PM
Subject: Receiver Save & Rolled back entries


>On a regularly scheduled basis, I do a journal switch & save the replaced
>journal receiver.  Until recently, when I did the save I was FREE'ing the
>storage used by the receiver.  There were many times when I could not do
>the FREE because the just replaced receiver contained journal entries which
>had not been committed or rolled back.  No problem, I did another save 1/2
>hour later to catch any receivers which had not been FREED.
>
>My question is, if the just saved receiver contains entries which are
>subsequently rolled back, is the saved receiver still valid for recovery
>purposes?  ie Will the system recognize the fact that an entry has been
>rolled back?  Is there an entry in the new receiver indicating that such
>and such a commit boundary has been rolled back or does the system just
>remove the entries from the old receiver.  If the latter, it seems to me
>that the saved receiver is no longer valid for recovery purposes.
>
>I hope this made sense.
>
>Gord
>
>--
>Gord Hutchinson
>TST Overland Express
>ghutchinson@tstoverland.com
>905-212-6330
>fax: 905 602-8895
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