[Koha-devel] Elasticsearch and facets

[David Cook]

Hi Claes,

 

I think the maxRecordsForFacets system preference might be a bit legacy at
this point. It was first used when we were building facets manually from
retrieved records from Zebra (which was an awful awful no good process).
However, I think most installations using Zebra these days use Zebra's
native faceting which uses the entire result set. At least that's how things
were a year or two ago. It may have changed since then. I'd have to
double-check, and I have a lot on at the moment, so I'll leave that for
yourself or someone else to check. In any case, we're all aware of the
limitations around that system preference, which is why we made the move to
Zebra's native faceting. (One easy thing to check is in your koha-conf.xml
file to see if "use_zebra_facets" is set to 1. If so, then I think
"maxRecordsForFacets" shouldn't have any effect.

 

I'm not very familiar with the ElasticSearch efforts, but I think it started
out as a like-for-like drop-in replacement. Making facets configurable would
be great, but I'm not sure anyone has this as a priority at the moment. I
think for now the main goal of ElasticSearch may be stability?

 

David Cook

Systems Librarian

Prosentient Systems

72/330 Wattle St

Ultimo, NSW 2007

Australia

 

Office: 02 9212 0899

Direct: 02 8005 0595

 

From: koha-devel-bounces at lists.koha-community.org
[mailto:koha-devel-bounces at lists.koha-community.org] On Behalf Of Claes
Eriksson
Sent: Monday, 19 February 2018 11:01 PM
To: koha-devel at lists.koha-community.org
Subject: [Koha-devel] Elasticsearch and facets

 

First some ranting about Zebra and then a question about ElasticSearch.

 

Using Zebra there is a Global system pref. called maxRecordsForFacets. By
default the number of records used to build the facet list is the first 20
results shown. You also get a warning in the manual to increase the number
since it will impact respons time. Building a facet list out of 20 records
may be enough for some people but if you think twice about it you realise
that it is quite misleading, especially since the user does not know that
the facet list is built on a very limited selection of records. Having the
sort set on Author and searching for realivity theory, the facet list may
not show Einstein if your library is specialised in physics and have a
fairly large collection.

 

I have high hopes for ElasticSearch to work with facets in a better way. The
best would be if all the index could be used for producing e.g. the author
facet and that it would have minimal impact on system performance. I
understand that there is discussion about making facets configurable (bug
18235) but I cannot see any traces of the improvements I would like to see,
but I may be wrong since I am quite new working with Koha.

 

Regards

Claes Eriksson, VTI, Sweden

 

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