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From: tim@ohday.sybase.com (Tim Wood)
Newsgroups: comp.databases
Subject: Re: Limitation on Informix Transaction Size
Message-ID: <12287@sybase.sybase.com>
Date: 10 Feb 91 23:05:23 GMT
References: <1991Jan25.171213.26493@tcom.stc.co.uk>
Sender: news@Sybase.COM
Organization: Sybase, Inc.
Lines: 20

In article <1991Jan25.171213.26493@tcom.stc.co.uk> patb@tcom.stc.co.uk (Patrick Brosnan) writes:
>There is a limitation with standard Informix (version 4) on Sun-4 workstations;
>the maximum number of rows that may be locked in a table within a transaction
>is 64. (Informix-Online does not have this problem.) Does anybody out there in
>the Void know if Ingress, Sybase and Oracle have similar limitations on Sun-4s.

Sybase's smallest unit of locking is the database page (usually 2K in size,
some platforms have 4K or more.)  We estimate how many pages a 
transaction needs to lock.  If that is a "large" estimate, or the 
estimate is too low and is exceeded at runtime, we then escalate the
lock to table-level, and release the page locks.  It is in principle possible
to run out of locks in Sybase, but I don't think it happens very often
because of this algorithm and because the number of locks available
in the server is DBA-configurable.
HTH,
-TW
Sybase, Inc. / 6475 Christie Ave. / Emeryville, CA / 94608	  415-596-3500
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