Queries vs. Filters

Question

I can\'t see any description of when I should use a query or a filter or some combination of the two. What is the difference between them? Can anyone please explain?

Answer 1

Few more addition to the same. A filter is applied first and then the query is processed over its results. To store the binary true/false match per document , something called a bitSet Array is used. This BitSet array is in memory and this would be used from second time the filter is queried. This way , using bitset array data-structure , we are able to utilize the cached result.

One more point to note here , the filter cache is created only when the request is executed hence only from the second hit , we actually get the advantage of caching.

But then you can use warmer API , to outgrow this. When you register a query with filter against a warmer API , it will make sure that this is executed against a new segment whenever it comes live. Hence we will get consistent speed from the first execution itself.

Answer 2

Queries : calculate score; thus they’re able to return results sorted by relevance. Filters : don’t calculate score, making them faster and easier to cache.