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.eriks...@vti.se<mailto:claes.eriks...@vti.se>
________________________________
Från: Tomas Cohen Arazi <tomasco...@gmail.com>
Skickat: den 20 februari 2018 01:13:18
Till: David Cook
Kopia: Claes Eriksson; koha-devel@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 
<dc...@prosentient.com.au<mailto:dc...@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-boun...@lists.koha-community.org<mailto:koha-devel-boun...@lists.koha-community.org>
 
[mailto:koha-devel-boun...@lists.koha-community.org<mailto:koha-devel-boun...@lists.koha-community.org>]
 On Behalf Of Claes Eriksson
Sent: Monday, 19 February 2018 11:01 PM
To: 
koha-devel@lists.koha-community.org<mailto:koha-devel@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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