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From Grant Ingersoll <>
Subject IndexWriter.getReader() was Re: How to leverage the LogMergePolicy "calibrateSizeByDeletes" patch in Solr ?
Date Tue, 22 Sep 2009 18:47:17 GMT
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  

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.


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