[Koha-devel] Elasticsearch and facets

Tue Feb 20 14:23:04 CET 2018

  1.  To begin with: “use_zebra_facets” was set to 1 in koha-conf.xml file, so that was not the problem.
  2.  Regarding Zebra’s native faceting I find some traces in an old RCF saying that it would be nice to replace "homegrown and inefficient routines for faceting" with Zebra’s native faceting. https://wiki.koha-community.org/wiki/C_%26_P_Search_Rewrite_RFC#.28e.29_Implement_search_engine_native_faceting.
  3.  I have also checked some libraries around the world with Koha set up by some of the larger consultants and they all handle facets in this way. I may ad to my ranting that it becomes a serious problem when it comes to subject facets. Narrowing down a search using subject facets that does only reflect the first 20 results is not helping a student or researcher. BTW, we tested setting default to 50 first results and response time increased with 5-8 seconds = not acceptable.
  4.  As I understand facets are hardcoded in Zebra and not at all configurable. If I am wrong I would be most grateful if you could hint me in the right direction. In ElasticSearch it is under discussion and not solved according to bug 18235?

The best
Claes
------------------------------------
Claes Eriksson
Information specialist

Department of Communication, Marketing and Library
Swedish National Road and Transport Research Institute (VTI)
VTI, SE-581 95 Linkoeping, Sweden
Tel: +46-13-20 40 00  Direct: +46-13-20 41 99
E-mail: claes.eriksson at vti.se<mailto:claes.eriksson at vti.se>
________________________________
Från: Tomas Cohen Arazi <tomascohen at gmail.com>
Skickat: den 20 februari 2018 01:13:18
Till: David Cook
Kopia: Claes Eriksson; koha-devel at lists.koha-community.org
Ämne: Re: [Koha-devel] Elasticsearch and facets

Facets are configurable, and goal is feature parity.
El lun., 19 de feb. de 2018 8:59 p. m., David Cook <dcook at prosentient.com.au<mailto:dcook at prosentient.com.au>> escribió:

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> [mailto: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<mailto: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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