Thank you, Adrien. That answers my questions.

On Wednesday, July 16, 2014 5:24:36 AM UTC-4, Adrien Grand wrote:
>
> On Tue, Jul 15, 2014 at 3:25 PM, David Smith <[email protected] 
> <javascript:>> wrote:
>
>> Thanks, Adrien. That brings me closer. 
>>
>> So when the documentations say doc values do not support filtering, it's 
>> talking about fielddata filtering for what's loaded into memory (anod not 
>> filtering as part of a query... say term filter).
>>
>
> Exactly.
>  
>
>> For further clarification - can a field that is not analyzed and only 
>> kept as doc values be used for querying/filtering (say a term filter on a 
>> numeric field or match query on a string field)? Or do all 
>> querying/filtering required the field to be in the uninverted index?
>>
>
> Doc values play no role when filtering (except for some filters that 
> support a `fielddata` mode, such as the range filter[1]). So if your field 
> has `index: no` you cannot use it in filters, and if it has `index: 
> not_analyzed` then you can, no matter whether doc values are enabled or not.
>
> [1] 
> http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-range-filter.html#_execution
>  
>
>> What I'm trying to understand how we can optimize querying/filtering in a 
>> large index (5 billion documents / 1 TB)? It's very hard to run a simple 
>> term filter because a bitset filter will need to be calculated that 
>> includes every single document. Wouldn't that utilize a lot of memory? Is 
>> there a way to speed that up?
>>
>
> If your filters are unlikely to be reused, then you should not cache them 
> by setting _cache to false. Caching filters only make filtering faster when 
> the likelyhood of reusing filters is high.
>
> -- 
> Adrien Grand
>  

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