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From "Yonik Seeley (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-1593) Optimizations to TopScoreDocCollector and TopFieldCollector
Date Mon, 04 May 2009 20:43:30 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1593?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12705732#action_12705732
] 

Yonik Seeley commented on LUCENE-1593:
--------------------------------------

bq. Or ... we can stop using BS at all and saying all scorers must work in-order.

Well, BS is the odd man out...  It's not currently used unless the user specifically sets
it up and it doesn't implement skipTo() (although the latter could be fixed presumably).

>> Another option to consider is use of a thread local to pass this info. A bit of a
hack, but it would be more localized.
> where would you set it?

Haven't seriously thought about it, but It could be set inside IndexSearcher.search() method
and checked in BooleanWeight.scorer().

> Optimizations to TopScoreDocCollector and TopFieldCollector
> -----------------------------------------------------------
>
>                 Key: LUCENE-1593
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1593
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>            Reporter: Shai Erera
>             Fix For: 2.9
>
>         Attachments: LUCENE-1593.patch, LUCENE-1593.patch, PerfTest.java
>
>
> This is a spin-off of LUCENE-1575 and proposes to optimize TSDC and TFC code to remove
unnecessary checks. The plan is:
> # Ensure that IndexSearcher returns segements in increasing doc Id order, instead of
numDocs().
> # Change TSDC and TFC's code to not use the doc id as a tie breaker. New docs will always
have larger ids and therefore cannot compete.
> # Pre-populate HitQueue with sentinel values in TSDC (score = Float.NEG_INF) and remove
the check if reusableSD == null.
> # Also move to use "changing top" and then call adjustTop(), in case we update the queue.
> # some methods in Sort explicitly add SortField.FIELD_DOC as a "tie breaker" for the
last SortField. But, doing so should not be necessary (since we already break ties by docID),
and is in fact less efficient (once the above optimization is in).
> # Investigate PQ - can we deprecate insert() and have only insertWithOverflow()? Add
a addDummyObjects method which will populate the queue without "arranging" it, just store
the objects in the array (this can be used to pre-populate sentinel values)?
> I will post a patch as well as some perf measurements as soon as I have them.

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