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From "Uwe Schindler" <>
Subject RE: Query.combine() has been removed in lucene 4.0 ??
Date Fri, 23 Nov 2012 11:08:31 GMT

this looks like a XY problem: You should explain first what you want to do, so we can find
a solution for you.

About Query.combine(): This method was solely a "helper" method only for use by the (Parallel-)MultiSearcher
classes in Lucene, which were deprecated in 3.x and completely removed in Lucene 4. MultiSearcher
had some serious problems with some type of queries (incorrect Boolean query expansion,...),
which was especially caused by this method - which was completely undocumented and behaving
wrong. The reason for this method was some custom rewrite logic, if a query must be executed
on different IndexSearchers where the term dictionaries on the underlying IndexReaders were

The replacement for MultiSearcher and ParallelMultiSearcher in Lucene 4.0 is to use MultiReader
with a single IndexSearcher and parallelization supported by passing an ExecutorSearvice to
the IndexSearcher. Query.combine was removed because the (broken) MultiSearcher-Rewrite-Hack
is no longer needed.


Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen

> -----Original Message-----
> From: slashone []
> Sent: Friday, November 23, 2012 8:27 AM
> To:
> Subject: Query.combine() has been removed in lucene 4.0 ??
> is this method has been moved to some other class ?
> please provide alternative ..
> --
> View this message in context:
> combine-has-been-removed-in-lucene-4-0-tp4021971.html
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