sybperl-l Archive

From: Marc Merlin <marcm at magic dot metawire dot com>
Subject: Re: How to find out when you're killed because of a deadlock?
Date: Apr 9 1998 11:15PM

On Thu, Apr 09, 1998 at 09:35:23AM -0400, David C Worenklein wrote:
> 
> The answer is in the Sybase manuals, if you know where to look.

I am the RTFM kind  of guy, but I'm not the Sybase DBA,  so I don't have the
said manuals :-) (I did ask the DBA though, but he didn't know).

> Create your Sybase handle thus:
> 
>   my $db = new Sybase::DBlib($USER, $PWD, $SERVER, $APPNAME, {DEADLOCK => 0});
> 
> Use this message handler:
> 
> sub SybMsgHandler {
>   my ($db, $message, $state, $severity, $text, $server, $procedure, $line) = @_;

Cool, good to know. Maybe it would be a good thing to add this to the manual
page, there is no mention of that command anywhere...

And Michael Peppler added:
> Whether dbsqlexec() returns FAIL for a problem or not depends on the
> query. If there is only one result set, dbsqlexec() will *normally*

Yes, I always launch queries one at a time.

> return FAIL, but you should always check the return code from
> dbresults() too (which will return FAIL if the query failed for any
> reason and dbsqlexec() returned SUCCEED).

I understand now that the Sybperl  documentation is meant for those who know
Sybase well, or at least its C API (I suppose that Sybperl is something very
similar).
However, it would maybe be a good idea to provide a safe snipplet of code in
the man page, that people can re-use.

Something along of the lines of:

$db->dbcmd($query);
($db->dbsqlexec == &SUCCEED) or die "Problem with the following query: \"$query\": $!";
# During a deadlock, dbsqlexec can unfortunately return SUCCEED, so we also
# need to make sure that dbresults is different from FAIL
($db->dbresults != FAIL) or die "The following query failed: \"$query\": $!"; 

The minor  problem is  that this piece  of code still  doesn't seem  to work
(meaning, I'm 98% sure that I had another undetected deadlock)
Can I test $db->dbresults against &SUCCEED instead?

Thanks a whole lot to the both of you, and the other ones who replied
Marc
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