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From "Sean Bridges (Created) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (LUCENE-3932) Improve load time of .tii files
Date Wed, 28 Mar 2012 19:53:28 GMT
Improve load time of .tii files
-------------------------------

                 Key: LUCENE-3932
                 URL: https://issues.apache.org/jira/browse/LUCENE-3932
             Project: Lucene - Java
          Issue Type: Improvement
    Affects Versions: 3.5
         Environment: Linux
            Reporter: Sean Bridges


We have a large 50 gig index which is optimized as one segment, with a 66 MEG .tii file. 
This index has no norms, and no field cache.

It takes about 5 seconds to load this index, profiling reveals that 60% of the time is spent
in GrowableWriter.set(index, value), and most of time in set(...) is spent resizing PackedInts.Mutatable
current.

In the constructor for TermInfosReaderIndex, you initialize the writer with the line,

{quote}GrowableWriter indexToTerms = new GrowableWriter(4, indexSize, false);{quote}

For our index using four as the bit estimate results in 27 resizes.

The last value in indexToTerms is going to be ~ tiiFileLength, and if instead you use,

{quote}int bitEstimate = (int) Math.ceil(Math.log10(tiiFileLength) / Math.log10(2));
GrowableWriter indexToTerms = new GrowableWriter(bitEstimate, indexSize, false);{quote}

Load time improves to ~ 2 seconds.

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