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https://issues.apache.org/jira/browse/LUCENE-3932?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael McCandless updated LUCENE-3932:
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    Attachment: LUCENE-3932.trunk.patch

Patch for trunk; I factored out the int-math-only log function to new static 
class oal.util.MathUtil, and re-used from one other place.
                
> 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
>         Attachments: LUCENE-3932.trunk.patch, perf.csv
>
>
> 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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