[Koha-bugs] [Bug 26457] DB DeadLock when renewing checkout items

[bugzilla-daemon at bugs.koha-community.org]

https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=26457

--- Comment #6 from David Cook <dcook at prosentient.com.au> ---
(In reply to didier from comment #5)
> (In reply to David Cook from comment #4)
> > 
> > I see that itemnumber_idx is redundant, but how is issuesborridx redundant?
> > It's not the same as bordate. 
> bordate is a composed index with borrowernumber first and mysql is able to
> use it for search on borrowernumber only.

That's interesting! I've had mixed experiences (with PostgreSQL) with composite
indexes being used when searching for only part of the index. I hadn't thought
about column order, but maybe that explains some of my experiences. Food for
thought!

> > > I'll try, maybe adding a fat sleep(5) in transaction block.
> > 
> > Certainly worth experimenting.
> I did it but was unable to reproduce the deadlock even with a sleep(5) and 8
> concurrent plack workers.

How many renewals did you try to do? I figure if you have maybe 32+ renewals
and the browser does about 8 requests in parallel, maybe you'd be able to
reproduce it with that.

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