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https://issues.apache.org/jira/browse/LUCENE-1990?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Toke Eskildsen updated LUCENE-1990:
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Attachment: LUCENE-1990-te20100301.patch
performance-20100301.txt
I've tested on two 32 bit Windows machines: An Intel T2400 (32 bit only)
running XP and an Athlon X2 4850e (64 bit capable) running 32 bit XP. The
result can be seen in attachment performance-20100301.txt. Something curious
happens with high (32+) bits/value for the T2400 as aligned overtakes packed.
However, the overall picture is still that aligned only wins for a few special
cases, so now I'll be happy to remove it from the patch. As a note, generated
is also slower than packed on the AMD processor, although not as much as for
Intel.
I have removed all traces of aligned from PackedInts, but kept the classes in
the patch, in the case that someone finds a faster way to handle aligned.
PackedIntsPerformance still includes both the generated switch-implementation
and Aligned32 and Aligned64. It should be possible to apply the patch without
Aligned32, Aligned64, AlignedWriter and PackedIntsPerformance.
> 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_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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