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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-1483) Change IndexSearcher multisegment searches to search each individual segment using a single HitCollector
Date Tue, 06 Jan 2009 14:14:44 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1483?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12661148#action_12661148
] 

Michael McCandless commented on LUCENE-1483:
--------------------------------------------

I prototyped a rough change to the FieldComparator API, whereby
TopFieldCollector calls setBottom to notify the comparator which slot
is the bottom of the queue (whenever it changes), and then calls
compareBottom (which replaces compare(int slot, int doc, float
score)).  This seems to offer decent perf. gains so I think we should
make this change for real?

I think it gives good gains because 1) compare to bottom is very
frequent for a search that has many hits, and where the queue fairly
quickly converges to the top N, 2) it allows the on-demand comparator
to pre-cache the bottom's ord, and 3) it saves one array deref.

TopFieldCollector would guarantee that compareBottom is not called
unless setBottom was called; during the startup transient, setBottom
is not called until the queue becomes full.



> Change IndexSearcher multisegment searches to search each individual segment using a
single HitCollector
> --------------------------------------------------------------------------------------------------------
>
>                 Key: LUCENE-1483
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1483
>             Project: Lucene - Java
>          Issue Type: Improvement
>    Affects Versions: 2.9
>            Reporter: Mark Miller
>            Priority: Minor
>         Attachments: LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch,
LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch,
LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch,
LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch,
LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch, LUCENE-1483.patch, sortBench.py,
sortCollate.py
>
>
> FieldCache and Filters are forced down to a single segment reader, allowing for individual
segment reloading on reopen.

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