Note that any other scoring mode (COMPLETE or COMPLETE_NO_SCORES) will mandatorily visit all hits, so there is no scope of skipping and hence no point of using impacts.
On Thu, Jul 11, 2019 at 8:51 AM Wu,Yunfeng <wuyunfen...@baidu.com> wrote: > > > @Adrien Grand <jpou...@gmail.com<mailto:jpou...@gmail.com>>. Thanks for your > reply. > > The explanation ` skip low-scoring matches` is great, I looked up some docs > and inspect some related code. > > I noticed the ` block-max WAND` mode only work when ScoreMode.TOP_SCORES is > used, is right? (The basic TermQuery would generate ImpactDISI with > scoreMode is TOP_SCORES.) > > Lucene compute max score per block and then cached in `MaxScoreCache` , this > means we can skip low-scoring block( current one block 128 DocIds) and in > competitive block still need to score any docId as seen, I confused with > `MaxScoreCache#getMaxScoreForLevel(int level)`, what the level mean? Skip > level? (Somewhere invoke this method pass one Integer upTo param) > > Thanks Lucene Team > > > 在 2019年7月10日，下午10:52，Adrien Grand > <jpou...@gmail.com<mailto:jpou...@gmail.com>> 写道： > > To clarify, the scoring process is not accelerated because we > terminate early but because we can skip low-scoring matches (there > might be competitive hits at the very end of the index). > > CompetitiveImpactAccumulator is indeed related to WAND. It helps store > the maximum score impacts per block of documents in postings lists. > Then this information is leveraged by block-max WAND in order to skip > low-scoring blocks. > > This does indeed help avoid reading norms, but also document IDs and > term frequencies. > > On Wed, Jul 10, 2019 at 4:10 PM Wu,Yunfeng > <wuyunfen...@baidu.com<mailto:wuyunfen...@baidu.com>> wrote: > > Hi, > > We discuss some topic from https://github.com/apache/lucene-solr/pull/595. As > Atri Sharma propose discuss with the java dev list. > > > Impact `frequency ` and `norm ` just to accelerate the `score process` which > `terminate early`. > > In impact mode, `CompetitiveImpactAccumulator` will record (freq, norm) pair > , would stored at index level. Also I noted `CompetitiveImpactAccumulator` > commented with `This class accumulates the (freq, norm) pairs that may > produce competitive scores`, maybe related to `WAND`? > > > The norm value which produced or consumed by `Lucene80NormsFormat`. > > In this ` Impact way`, we can avoid read norms from `Lucene80NormsProducer` > that may generate the extra IO? （ the norm value Lucene stored twice.）and > take full advantage of the WAND method? > > > > -- > Adrien > --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
