[Koha-devel] Elasticsearch and facets

Tue Feb 20 17:28:13 CET 2018

Hello Claes,

About Zebra first: maxRecordsForFacets is only used if facets are not built
from Zebra (use_zebra_facets=0).
If facets are retrieved from Zebra you may face performance issue depending
on the number of records you have in your catalogue (see bug 13665). You
can then play with the parameter "facetNumRecs" in your zebra config file
(default is 1000).

Regarding Elastic: Facets are not configurable yet, but will be with the
patches on bug 18235. It is a priority for me and that is why I proposed a
patch one year ago. You can easily test it and provide us feedback.

Regards,
Jonathan

On Tue, 20 Feb 2018 at 10:23 Claes Eriksson <claes.eriksson at vti.se> wrote:

>
>    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 <+46%2013%2020%2040%2000>  Direct: +46-13-20 41 99
> <+46%2013%2020%2041%2099>
> E-mail: 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> 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 <02%2092%2012%2008%2099>
>
> Direct: 02 8005 0595 <02%2080%2005%2005%2095>
>
>
>
> *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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> --
>
> Tomás Cohen Arazi
>
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