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From MitchK <>
Subject Re: RequestHandler / function Query with Cache-implementation
Date Tue, 27 Apr 2010 21:26:33 GMT

Hi Chris,

Chris Hostetter-3 wrote:
> I'm not entirely sure i undestand what you're asking, but have you looked 
> at ExternalFileField ? ... what you are describing sounds an awful lot 
> like using it in a FunctionQuery
Yes, it's really a lot. I am not sure whether an ExternalFileField-source
would work faster than a SolrCache (a lot of the needed data is always the
same, so it's okay to store it in an external file). However: is it really
more performant to get the metadata from there? Did you make any experiences

I *think* SolrJ is the right way to get stats and other things about my
index directly from the server. I just need to query them and store them in
a cache**. That's all. I can reuse them everytime. In fact I only need SolrJ
to fill the cache, if it is empty (or a special event gets fired).

> but you can declare any custom instances of a SolrCache that you 
> want in your solrconfig.xml (there is an example commented out in the 
> example solrconfig.xml -- look for "myUserCache") which you can then 
> access in any custom plugin you want using SolrIndexSearcher (getCache, 
> cacheInsert, cacheLookup, etc... any of hte cache methods that take a 
> cacheName) 
Thank you *very* much. I didn't know how to access them, so I spent a few
hours today to search for a solution. By the way - do I learn more about
such special cases if I have a look at "Solr 1.4
Enterprise-Search-Server-Book" or "Lucene in Action"? It is really
frustrating when you want to get things done but don't know where to start.
I don't know which of these books to buy first and which of both fits such
needs more. But thats off topic, of course. :)

> I've implemented some custom metadata caches (for driving complex 
> faceting) like this, but i'm afraid i can't share the code examples. 
Complex faceting is a really interesting topic. 
You talked about conditional faceting a few years ago.
It's a really interesting topic and I hope I can spent some time on that in

**before I am going to start writing the first lines of code, I need to know
about how Solr uses function queries. Is there a new instance of the
function query per request, per Solr-lifetime, per...what??


Grant Ingersoll-2 wrote:
> Have you looked at the File based ValueSource in Solr?  It can be loaded
> per commit and is designed to hold precomputed scores that are then
> factored in via Function queries.
Yes, I did. Honestly, I didn't understand how to use this function query,
because there was no example given (how should a file for that usecase looks
like? When should which score applies?). 

My usecase will look like a conditional score:
- getting the value x of a field
- lookup in the cache (or map) for the value of map.get(x)
- lookup in another cache for map.get(value)
- computing a custom score-factor and returning it

I hope this helps understanding my issue a little bit better.

Thank you both!

Kind regards
- Mitch
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