Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!rochester!rutgers!att!ulysses!attibr!mjm
From: mjm@attibr.UUCP (Mike Matthews)
Newsgroups: comp.databases
Subject: Re: Strange problems with Informix Perform
Summary: Informix Limits
Keywords: Informix perform nohangup?
Message-ID: <130@attibr.UUCP>
Date: 3 Feb 89 21:51:41 GMT
References: <34891@codas.att.com> <4723@sfsup.UUCP>
Organization: AT&T International, Basking Ridge, NJ
Lines: 31

> Perform is a strange beast.  Seems to handle boundary conditions very poorly.
> I suspect there are fixed size tables for user functions, lookups, etc; when
> you exceed them unpredictable things start to happen!  I have seen perform 
> screens stop functioning when a new user-defined functions were added; also
> seen lookup's fail to work when a screen had too many of them.  Never took 
> the time to diagnose exactly when these things stop working.
	Perform will not allow lookups of more then 12 tables which is described
in the 2.10 manual.
	Perform and Ace have definite limits that neither compiler ( saceprep or
formbuild ) are intelligent to warn about. The after effects can be quite
painful and often do not appear until later versions are installed.
We had a Perform application where a programmer had ignored the above mentioned
limit but the application ran any way until the Informix version was upgraded.
The perform screen started exhibiting the same behavior as described in the
HUPCL problem mentioned, essentially bringing a 3B2 to it knees, much to the
surprise of the system administrators doing the upgrade.
	An ace report that results in a row greater than PAGE_SIZE -
( 32 + 4 ) will bomb with any one of many strange messages. Why can`t saceprep
tally the row size and produce a warning giving a clue to the subsequent
run-time problem?
> 
> Also, never could get ESQL to work from within sperform.  Had to run SQL 
> calls in a child.  Is this a feature or a bug?
> 
The perform language is explicitly defined in the manual. I don't think
any extra-language constructs or references are supported. Don't you have
any manuals???

Mike Matthews
ATT International
Tech Support