It is my understanding that facets are built off the first page of search results. It seems that home libraries, locations and item types are all facets that should be completely available regardless of the first page of results, especially when you click "Show more". I would suggest this be changed to include all the fixed facets rather than being random.
Well, that explains a few things - like why "show more" does not always appear, seemingly at random. When there are more than 5 facets in a category within search results, but if the first page has only 5 or less the "Show more" link is missing. The searcher is not offered a way to use the facets found in the rest of the search results. It raises the question - why are the facets built from the first page only? Is there an unacceptable performance hit? This is certainly something the average user would not expect, and gives the impression that the system is not finding facets they would want to use. Yes item type and location, but also series ...
There are currently 2 ways, but both have issues: 1) Use Zebra facets - the whole result set is used to build the facets, but unfortunately we found it too slow on big databases to be usable. (see 136659 2) Use Koha facets - you can use the maxRecordsForFacets system preference to choose how many records are used for the facets (20 = first page is the default). But the higher you set the number, the longer it will take. What option is used is set in the koha-conf.xml file. You are both right - the situation now is far from being good, but at the moment to my knowledge there is no real good way at least for bigger databases to make this work nicely.
Typoed the bug number in 1) - the bug is bug 13665.
OK, would it be possible for "Show More" to appear for all categories, regardless of the number of facets retrieved, and the rest of the facets be generated from all search results only when Show more is clicked? That way there is not increased performance hit for the first page, but all possible facets can be accessed if needed.
Hm, it could work a little better than it does now that way. But with elastic search around the corner I am not sure someone will give rewriting the facets code a go.
I think having Koha add a complete list of facet for some categories (this should be an option), rather than the database building these particular facets, would be more reliable, and maybe even faster, as the database does not have to compile and generate them.
I guess you could always display, say, all item types, but we couldn't display the number of records behind it then and also it would show item types that are not part of the search result. Would be interesting to get some idea how well this works with Elastic at the moment.
+1