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From Jason Rutherglen <>
Subject Re: IndexWriter.getReader() was Re: How to leverage the LogMergePolicy "calibrateSizeByDeletes" patch in Solr ?
Date Tue, 22 Sep 2009 18:55:12 GMT
> which one is better

Better for what? What use case are you thinking of?

The merge reasons were covered well in the previous thread.
Another gain is the carry over of deletes in RAM.

I'm getting the feeling the Realtime wiki needs a lot of work.

On Tue, Sep 22, 2009 at 11:47 AM, Grant Ingersoll <> wrote:
> Slight divergence from the topic...
> On Sep 22, 2009, at 10:48 AM, Michael McCandless wrote:
>> John are you using IndexWriter.setMergedSegmentWarmer, so that a newly
>> merged segment is warmed before it's "put into production" (returned
>> by getReader)?
> One of the pieces I still am missing from all of this is why isn't
> IW.getReader() now just the preferred way of getting a IndexReader for all
> applications other than those that are completely batch oriented?  Why
> bother with IndexReader.reopen()?  IW.getReader() is marked as Expert right
> now, which says to me there are some tradeoffs or that one needs to be
> really careful using it, but I don't see the downside other than what
> appears to be some extra resources consumed and the fact that it is brand
> new code, or at least the downside is not documented.
> And yet, at the first SF Meetup, I recall having a discussion with Michael
> B. about this approach versus IR.reopen() that left me wondering which one
> is better, since, Lucene has, in fact, always been about incremental updates
> (since there are commercial systems out there that require complete
> re-indexing) and that getting IR.reopen to perform is just a matter of
> tuning one's application in regards to reads and writes vs. having to do all
> this work in the IndexWriter that now tightly couples the IndexReader to the
> IndexWriter.  Hopefully Michael can refresh my memory on the conversation,
> as I may be remembering incorrectly.
> -Grant
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