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From "Michael McCandless (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-3932) Improve load time of .tii files
Date Thu, 29 Mar 2012 16:56:26 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-3932?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13241386#comment-13241386
] 

Michael McCandless commented on LUCENE-3932:
--------------------------------------------

I agree net/net that change is good; we know the in-RAM image will be at least as large as
the tii file so we should make a better guess up front.

3.x is currently in code freeze (for the 3.6.0 release), but I'll commit to trunk's preflex
codec.

Can you describe more about your index...?  If your tii fils is 66 MB, how many terms do you
have...?  5 seconds is also a long startup time... what's the IO system like?
                
> 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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