[jira] [Comment Edited] (LUCENE-6198) two phase intersection

["Yonik Seeley (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-6198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14289801#comment-14289801 ] 

Yonik Seeley edited comment on LUCENE-6198 at 1/23/15 7:41 PM:
---------------------------------------------------------------

I had thought about this a while ago via adding something like 

{code}
interface ApproximateDISI {
  int guessNext();  // returns next doc that has a chance of matching
  int guessAdvance(int target);  // returns next doc after target that has a chance of matching
  boolean matches();
}
{code}

And then some scorers could optionally implement ApproximateDISI.
So I guess the main diff would come down to "instanceof ApproximateDISI" vs "getApproximation() != null" ?
edit: Although I think I do like the increased reuse potential of your way... it's just another DISI.



was (Author: yseeley@gmail.com):
I had thought about this a while ago via adding something like 

{code}
interface ApproximateDISI {
  int guessNext();  // returns next doc that has a chance of matching
  int guessAdvance(int target);  // returns next doc after target that has a chance of matching
  boolean matches();
}
{code}

And then some scorers could optionally implement ApproximateDISI.
So I guess the main diff would come down to "instanceof ApproximateDISI" vs "getApproximation() != null" ?


> two phase intersection
> ----------------------
>
>                 Key: LUCENE-6198
>                 URL: https://issues.apache.org/jira/browse/LUCENE-6198
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Robert Muir
>         Attachments: LUCENE-6198.patch
>
>
> Currently some scorers have to do a lot of per-document work to determine if a document is a match. The simplest example is a phrase scorer, but there are others (spans, sloppy phrase, geospatial, etc).
> Imagine a conjunction with two MUST clauses, one that is a term that matches all odd documents, another that is a phrase matching all even documents. Today this conjunction will be very expensive, because the zig-zag intersection is reading a ton of useless positions.
> The same problem happens with filteredQuery and anything else that acts like a conjunction.



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