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From "Toke Eskildsen (JIRA)" <j...@apache.org>
Subject [jira] Issue Comment Edited: (LUCENE-1990) Add unsigned packed int impls in oal.util
Date Thu, 01 Apr 2010 21:34:27 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12852557#action_12852557
] 

Toke Eskildsen edited comment on LUCENE-1990 at 4/1/10 9:33 PM:
----------------------------------------------------------------

It seem like my unit-testing of PackedInts.Mutable wasn't good enough. There is a bug in Packed64
(and probably in Packed32 too) when using the set-method. In certain cases the secondary block
is changed when it should be left alone. A simple unit-test is
{code}
    PackedInts.Mutable mutable = PackedInts.getMutable(26, 5);
    mutable.set(24, 31);
    mutable.set(4, 16);
    assertEquals("The value #24 should remain unchanged", 31, mutable.get(24));
{code}

The PackedWriter uses a different algorithm for generating the bit stream and is unaffected
by this bug.

I expect the write-masks for the set-method to be at fault and I am working on a fix. ETA:
Within an hour or sometime during the weekend, depending on difficulty.

      was (Author: toke):
    It seem like my unit-testing of PackedInts.Mutable wasn't good enough. There is a bug
in Packed64 (and probably in Packed32 too) when using the set-method. In certain cases the
secondary block is changed when it should be left alone. A simple unit-test is
{code}
    PackedInts.Mutable mutable = PackedInts.getMutable(26, 5);
    mutable.set(24, 16);
    mutable.set(4, 16);
    assertEquals("The value #24 should remain unchanged", 31, mutable.get(24));
{code}

The PackedWriter uses a different algorithm for generating the bit stream and is unaffected
by this bug.

I expect the write-masks for the set-method to be at fault and I am working on a fix. ETA:
Within an hour or sometime during the weekend, depending on difficulty.
  
> Add unsigned packed int impls in oal.util
> -----------------------------------------
>
>                 Key: LUCENE-1990
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1990
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>    Affects Versions: Flex Branch
>            Reporter: Michael McCandless
>            Priority: Minor
>             Fix For: Flex Branch
>
>         Attachments: generated_performance-te20100226.txt, LUCENE-1990-te20100122.patch,
LUCENE-1990-te20100210.patch, LUCENE-1990-te20100212.patch, LUCENE-1990-te20100223.patch,
LUCENE-1990-te20100226.patch, LUCENE-1990-te20100226b.patch, LUCENE-1990-te20100226c.patch,
LUCENE-1990-te20100301.patch, LUCENE-1990.patch, LUCENE-1990.patch, LUCENE-1990_PerformanceMeasurements20100104.zip,
perf-mkm-20100227.txt, performance-20100301.txt, performance-te20100226.txt
>
>
> There are various places in Lucene that could take advantage of an
> efficient packed unsigned int/long impl.  EG the terms dict index in
> the standard codec in LUCENE-1458 could subsantially reduce it's RAM
> usage.  FieldCache.StringIndex could as well.  And I think "load into
> RAM" codecs like the one in TestExternalCodecs could use this too.
> I'm picturing something very basic like:
> {code}
> interface PackedUnsignedLongs  {
>   long get(long index);
>   void set(long index, long value);
> }
> {code}
> Plus maybe an iterator for getting and maybe also for setting.  If it
> helps, most of the usages of this inside Lucene will be "write once"
> so eg the set could make that an assumption/requirement.
> And a factory somewhere:
> {code}
>   PackedUnsignedLongs create(int count, long maxValue);
> {code}
> I think we should simply autogen the code (we can start from the
> autogen code in LUCENE-1410), or, if there is an good existing impl
> that has a compatible license that'd be great.
> I don't have time near-term to do this... so if anyone has the itch,
> please jump!

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