Right, that makes sense usually. But there are use cases for post-filtering. A good example is when a collector performs grouping or windowing and we want to apply filters based on the grouped or windowed values.
On Thu, Aug 16, 2018 at 4:22 AM Adrien Grand <jpou...@gmail.com> wrote: > I think one reason that we don't want to encourage filtering at the > collector level is that it is much slower than filtering in the query. The > former needs to check hits one by one while the latter can use leap frog to > skip documents that don't match. > > Le mer. 15 août 2018 à 23:27, Michael Sokolov <msoko...@gmail.com> a > écrit : > > > Hmm the more I root around, the more crazy it seems to try to thread a > > return value through all the different places collect() gets called from. > > Somehow I thought it would just be one place in IndexSearcher somewhere. > > > > On Wed, Aug 15, 2018 at 5:18 PM Michael Sokolov <msoko...@gmail.com> > > wrote: > > > > > We have MultiCollector to enable running multiple Collectors on the > same > > > hits, in sequence for each hit. I think a nice extension would be to > > enable > > > filtering so that earlier collectors could reject a hit, preventing > later > > > collectors from seeing it. This way you could have a post-filter > > > implemented in one collector, and some other collection, like faceting, > > in > > > the next one, that wants to ignore hits that are filtered in this > > > post-filter. > > > > > > The implementation idea would be to return a "status" value from > > > LeafCollector.collect() indicating how to proceed. This could also > > > naturally be used for early termination (you could have > status=TERMINATE > > | > > > SKIP | COLLECT, say). > > > > > > I was trying to undertsand why this wasn't done before for early > > > termination since it seemed so natural to me, and thought - there must > > be a > > > reason. But I went and read through (skimmed really) the original > > > EarlyTerminatingCollector issue ( > > > https://issues.apache.org/jira/browse/LUCENE-4858) and didn't see any > > > discussion of that. > > > > > > Am I missing something here? > > > > > > -Mike > > > > > >
