[Koha-devel] Serious problem

[David Cook]

Mmm, I think that I see what you're saying. In theory, for a library with
high circulation, you would always have a newer checkout in the issues
table, when you're doing a check-in, so it's unlikely that your IDs in the
issues table would be lower than your IDs in your old_issues table.

When I referred to frequency, I meant that there is probably a higher
frequency of checking in items or fulfilling/cancelling reserves than
deleting biblio records, although I suppose that's a subjective claim.  In
any case, that's a good point that the auto_increment is more likely to
happen in a library with low circulation than high circulation.

I've noticed this problem for years, but previously my communications about
it have been ignored, so we've just mitigated it locally via scripts.
Historically, we thought it only happened after running OPTIMZE TABLE, but
thanks to Mark we see that it's also after MySQL server restarts. 

David Cook
Systems Librarian
Prosentient Systems
72/330 Wattle St
Ultimo, NSW 2007
Australia

Office: 02 9212 0899
Direct: 02 8005 0595


> -----Original Message-----
> From: Chris Cormack [mailto:chrisc at catalyst.net.nz]
> Sent: Tuesday, 6 September 2016 11:40 AM
> To: David Cook <dcook at prosentient.com.au>
> Cc: 'Koha-devel' <koha-devel at lists.koha-community.org>
> Subject: Re: [Koha-devel] Serious problem
> 
> * David Cook (dcook at prosentient.com.au) wrote:
> >
> > Chris, what about deletedbiblio and deletedbiblioitem tables? The
> > history there might be more important, as I think we're now including
> > those in the OAI-PMH responses? I reckon those tables would be
> > vulnerable to this as well, although perhaps less likely due to issues
> > and reserves being more high frequency in terms of inserts/deletions.
> >
> 
> As Katrin rightly pointed out to me, frequency is not really the issue.
> This is only a problem when the most recently inserted item is
> deleted/return/issued.
> And then the server is restarted right then.
> 
> If you delete from anywhere except the tip of the table, it doesn't
matter.
> So if you issue and return something (before anyone else issues something)
> and restart the server then you have the problem with issues.
> So in fact the higher the frequency the way less likely this will be to
happen.
> 
> It will most likely only ever happen in a library that does almost no
circulation.
> 
> Chris
> 
> --
> Chris Cormack
> Catalyst IT Ltd.
> +64 4 803 2238
> PO Box 11-053, Manners St, Wellington 6142, New Zealand