-----Original Message----- From: David Cook [mailto:dcook@prosentient.com.au] Sent: Tuesday, 6 September 2016 11:57 AM To: 'Chris Cormack' <chrisc@catalyst.net.nz> Cc: 'Koha-devel' <koha-devel@lists.koha-community.org> Subject: RE: [Koha-devel] Serious problem
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
A quick look through the data for one library which recently had this problem shows that I'm wrong about the frequency of issues/reserves vs deleted biblios actually. Very low circulation but lots of deleted records. David Cook Systems Librarian Prosentient Systems 72/330 Wattle St Ultimo, NSW 2007 Australia Office: 02 9212 0899 Direct: 02 8005 0595 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@catalyst.net.nz] Sent: Tuesday, 6 September 2016 11:40 AM To: David Cook <dcook@prosentient.com.au> Cc: 'Koha-devel' <koha-devel@lists.koha-community.org> Subject: Re: [Koha-devel] Serious problem
* David Cook (dcook@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