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Date: Sun, 18 Aug 2013 22:06:42 +0300
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Subject: How important is single segment optimization to Search time
 performance?
From: Gili Nachum <gilinachum@gmail.com>
To: java-user@lucene.apache.org
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Hi there Lucene samurai!

*I was wondering how important is single segment merging for search time
performance compared to a more modest merging goal like merging down to
just 4 segment.
*

Currently my system merges every evening, it takes ~1-2 hours, and
invalidates the File-system cache.
What would happen if I'll reduce the merging target to just 4 segments?
e.g., When searching a term, does Lucene needs to visit each segment (disk
seek operation) to access the relevant posting list? If not then what's the
advantage of merging down segments (besides open files limit).

*Was wondering if anyone has tested # of segments against search time
performance?*

I should add I have ~10 indexes, at a total size of 50GB, and I use
mutli-index searcher to search over them (Lucene 3.0.3 - yeah it's old I
know). The index is updated every 15min.

Gili Nachum.

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