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From "Sean Bridges (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-3932) Improve load time of .tii files
Date Thu, 29 Mar 2012 19:56:22 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-3932?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13241577#comment-13241577
] 

Sean Bridges commented on LUCENE-3932:
--------------------------------------

{quote}Do you have comparisons with pre-3.5 (before we cutover to this more RAM-efficient
(but CPU heavy on load) terms index)? Probably that less CPU on init, but more RAM held for
the lifetime of the reader...?{quote}

Trying with 3.4 gives a 4 second load time, most of the time spent in SegmentTermEnum.next().


{quote}For an index like that, have you tried specifying termInfosIndexDivisor to your IndexReader
as well?
If it works with ok performance, then you could remove it adjust termIndexInterval at write-time
to have a smaller .tii{quote}

Thanks, I will try that.
                
> 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: 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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