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From: garyp@cognos.uucp (Gary Puckering)
Newsgroups: comp.databases
Subject: Re:  Degree 3 consistency
Message-ID: <1381@smokey.UUCP>
Date: Tue, 1-Sep-87 16:09:43 EDT
Article-I.D.: smokey.1381
Posted: Tue Sep  1 16:09:43 1987
Date-Received: Thu, 3-Sep-87 04:00:20 EDT
References: <1215@smokey.UUCP> <18182UH2@PSUVM> <1301@smokey.UUCP> <3391@zen.berkeley.edu>
Reply-To: garyp@cognos.UUCP (Gary Puckering)
Organization: Cognos Inc., Ottawa, Canada
Lines: 15

In article <3391@zen.berkeley.edu> larry@xanadu.UUCP (Larry Rowe) writes:
>So, the ``theory'' that relational systems use was, in fact, implemented
>in IMS.  moreover, DB2 uses the same transaction manager as IMS.  consequently,
>the xact functionality issue is really an issue of what an individual
>system implementer chooses to implement.  some relational systems support
>something other than degree 3 consistency, others don't.  

Does this mean that degree-3 consistency can be obtained in IMS?  If
so, what method is used to eliminate "phantoms".  Most relational
systems use index or table locking for this.  What does IMS do?
-- 
Gary Puckering                                   P.O. Box 9707
Cognos Incorporated                              3755 Riverside Dr.
VOICE:  (613) 738-1440   FAX: (613) 738-0002     Ottawa, Ontario
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