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From "Adrien Grand (JIRA)" <>
Subject [jira] [Updated] (LUCENE-4098) Efficient bulk operations for packed integer arrays
Date Fri, 01 Jun 2012 13:26:22 GMT


Adrien Grand updated LUCENE-4098:

    Attachment: LUCENE-4098.patch

Slightly updated patch that fixes the computation of maxValue in GrowableWriter and uses |
instead of Math.max to compute the max value when performing a bulk set (since GrowableWriter
only works with unsigned integers).

As a side note, the reason why I didn't write bulk get and set methods for Packed64 is that
I didn't find how to do it efficiently (= with less instructions and no conditional) without
writing specialized methods for every bitsPerValue.
> Efficient bulk operations for packed integer arrays
> ---------------------------------------------------
>                 Key: LUCENE-4098
>                 URL:
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: core/other
>            Reporter: Adrien Grand
>            Priority: Minor
>             Fix For: 4.1
>         Attachments: LUCENE-4098.patch
> There are some places in Lucene code that {iterate over,set} ranges of values of a packed
integer array. Because bit-packing implementations (Packed*) tend be slower than direct implementations,
this can take a lot of time.
> For example, under some scenarii, GrowableWriter can take most of its (averaged) {{set}}
time in resizing operations.
> However, some bit-packing schemes, such as the one that is used by {{Packed64SingleBlock*}},
allow to implement efficient bulk operations such as get/set/fill. Implementing these bulk
operations in {{PackedInts.{Reader,Mutable}}} and using them across other components instead
of their single-value counterpart could help improve performance.

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