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From Michael McCandless <>
Subject Re: Consolidate MP and LMP
Date Thu, 02 Dec 2010 11:09:57 GMT
2010/12/2 Shai Erera <>:

> Hmm .. now that I look closely at it, MP has useCompundFile/DocStore
> methods, and LMP just adds getUseCompoundFile(). Why?
> And IndexWriter.addIndexes(IndexReader...) queries instanceof LMP, instead
> of calling mp.useCompoundFile()?

Hmm I don't know.

> So perhaps we should:
> 1) Fix IW to not case to LMP just to ask if it should create compound files
> or not. And then we can perhaps remove getLogMergePolicy from IW on 3x, and
> also removing the source for confusion.


> 2) Look at LMP and decide if there are method we believe can be placed on a
> general MP, such as mergeFactor or maxMergeDocs. LogMP is special in how it
> picks segments for merge - that is, log-based (levels). But maxMergeDocs,
> maxMergeSize, mergeFactor, are unrelated to log/levels. This is the sort of
> functionality I'd expect to find on a general MP impl.

We have to be careful.... eg a future MP could have a minMergeFactor
and maxMergeFactor (or, even, no bounds) and so having mergeFactor on
the parent isn't great.


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