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From Michael McCandless <luc...@mikemccandless.com>
Subject Re: What does "out of order" mean?
Date Fri, 27 Nov 2009 11:07:07 GMT
It refers to the order in which the docIDs are delivered to your Collector.

"Normally" they are always delivered in increasing order.

However, some queries (well, currently only certain BooleanQuery
cases) can achieve substantial search speedup if they are allowed to
deliver docIDs to your collector out of order.  In this case, docs are
processed in batches (chunks of 1024 docIDs at once), and within a
batch you may receive docIDs out of order.

Many collectors don't mind getting docIDs out of order, and so it's
important to return "true" from your acceptDocsOutOfOrder method so
Lucene can allow BooleanQuery to run faster.

Mike

On Fri, Nov 27, 2009 at 5:51 AM, Alexander Veit
<alexanderv@dev.unitedplanet.de> wrote:
> Hi,
>
> The documentation of org.apache.lucene.search.Collector uses the obscure
> term "out of order". What does "order" mean? The natural order of document
> IDs, a scoring order, or some other order?
>
> --
> Cheers,
> Alex
>
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