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Jul 19, 2012, 5:13 PM
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[jira] [Updated] (LUCENE-4239) Provide access to PackedInts' low-level blocks <-> values conversion methods
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[ https://issues.apache.org/jira/browse/LUCENE-4239?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Adrien Grand updated LUCENE-4239:
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Attachment: LUCENE-4239.patch
First shot. I created two interfaces {{PackedInts.Decoder}} and {{PackedInts.Encoder}} that expose the {{BulkOperation}} methods. Similarly to {{PackedIntsDecompress}}, I used java.nio buffers to leverage the byte/int/long buffer conversions ({{ByteBuffer.asIntBuffer}}, ...). This is not ready to commit, I still need to run tests to see whether it hurts performance...
> Provide access to PackedInts' low-level blocks <-> values conversion methods
> ----------------------------------------------------------------------------
>
> Key: LUCENE-4239
> URL: https://issues.apache.org/jira/browse/LUCENE-4239
> Project: Lucene - Java
> Issue Type: Improvement
> Components: core/other
> Reporter: Adrien Grand
> Assignee: Adrien Grand
> Priority: Minor
> Fix For: 4.0
>
> Attachments: LUCENE-4239.patch
>
>
> In LUCENE-4161 we started to make the {{PackedInts}} API more flexible so that codecs could use it whenever they need to (un)pack integers. There are two posting formats in progress (For and PFor, LUCENE-3892) that perform a lot of integer (un)packing but the current API still has limits :
> - it only works with long[] arrays, whereas these codecs need to manipulate int[] arrays,
> - the packed reader iterators work great for unpacking long sequences of integers, but they would probably cause a lot of overhead to decode lots of short integer sequences such as the ones that can be generated by For and PFor.
> I've been looking at the For/PFor branch and it has a {{PackedIntsDecompress}} class (http://svn.apache.org/repos/asf/lucene/dev/branches/pforcodec_3892/lucene/core/src/java/org/apache/lucene/codecs/pfor/PackedIntsDecompress.java) which is very similar to {{oal.util.packed.BulkOperation}} (package-private), so maybe we should find a way to expose this class so that the For/PFor branch can directly use it.
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