Thanks, Jack, Alex and Shawn. This makes proper sense. One win of rounding down on indexing side is saving index space, according to hoss (reply over IRC):
"with the TrieDateFields, rounding dates at indexing time won't have any effect on the cachability of the rounded queries, and even for non cached queries it shouldn't affect the performance much -- but yes, it would help reduce index size" I haven't tried it myself, just thought to ask if somebody tried it already. Dmitry On Sat, May 17, 2014 at 8:37 AM, Shawn Heisey <s...@elyograg.org> wrote: > On 5/15/2014 1:34 AM, Alexandre Rafalovitch wrote: > > I thought the date math rounding was for _caching_ the repeated > > queries, not so much the speed of the query itself. > > Absolutely correct. When NOW is used without rounding, caching is > completely ineffective. This is because if the same query using NOW is > sent multiple times several seconds apart, every one of those queries > will be different after they are parsed and NOW is converted to an > actual timestamp. > > > Also, if you are using TrieDateField, precisionStep value is how > > optimization is done. There is bucketing at different level of > > precision, so the range search works at the least granular level > > first, etc. > > Some nitty-gritty details of how range queries are accelerated with the > Trie data types and precisionStep are described in the Javadoc for > NumericRangeQuery: > > > http://lucene.apache.org/core/4_8_0/core/org/apache/lucene/search/NumericRangeQuery.html > > Thanks, > Shawn > > -- Dmitry Kan Blog: http://dmitrykan.blogspot.com Twitter: http://twitter.com/dmitrykan
