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https://issues.apache.org/jira/browse/LUCENE-2130?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12787248#action_12787248
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Mark Miller commented on LUCENE-2130:
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Okay - so talking to Robert in chat - the advantage when you are enumerating a
lot of terms is that you avoid DirectoryReaders MultiTermEnum and its PQ.
> Investigate Rewriting Constant Scoring MultiTermQueries per segment
> -------------------------------------------------------------------
>
> Key: LUCENE-2130
> URL: https://issues.apache.org/jira/browse/LUCENE-2130
> Project: Lucene - Java
> Issue Type: Improvement
> Reporter: Mark Miller
> Priority: Minor
>
> This issue is likely not to go anywhere, but I thought we might explore it.
> The only idea I have come up with is fairly ugly, and unless something better
> comes up, this is not likely to happen.
> But if we could rewrite constant score multi-term queries per segment, MTQ's
> with auto, constant, or constant boolean rewrite could enum terms against a
> single segment and then apply a boolean query against each segment with just
> the terms that are known to be in that segment. This way, if you have a bunch
> of really large segments and a lot of really small segments, you wouldn't
> apply a huge booleanquery against all of the small segments which don't have
> those terms anyway. How advantageous this is, I'm not sure yet.
> No biggie, not likely, but what the heck.
> So the ugly way to do it is to add a property to query's and weights -
> lateCnstRewrite or something, that defaults to false. MTQ would return true
> if its in a constant score mode. On the top level rewrite, if this is
> detected, an empty ConstantScoreQuery is made, and its Weight is turned to
> lateCnstRewrite and it keeps a ref to the original MTQ query. It also gets
> its boost set to the MTQ's boost. Then when we are searching per segment, if
> the Weight is lateCnstRewrite, we grab the orig query and actually do the
> rewrite against the subreader and grab the actual constantscore weight. It
> works I think - but its a little ugly.
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