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Posted to issues@lucene.apache.org by "Michael Sokolov (Jira)" <ji...@apache.org> on 2021/01/12 15:52:00 UTC
[jira] [Comment Edited] (LUCENE-9663) Adding compression to terms
dict from SortedSet/Sorted DocValues
[ https://issues.apache.org/jira/browse/LUCENE-9663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17263442#comment-17263442 ]
Michael Sokolov edited comment on LUCENE-9663 at 1/12/21, 3:51 PM:
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Interesting - if you are running luceneutil tests, could you please also report QPS changes? I'm not clear what the usage of this {{keywords}} field is exactly - is it used for aggregations? It would be good to run a faceting test; luceneutil doesn't really have any tests of high-cardinality SSDV aggregations; I think day-of-year is the closest it gets. Maybe you could add one? It's important to test the impact on the query side.
was (Author: sokolov):
Interesting - if you are running luceneutil tests, could you please also report QPS changes?
> Adding compression to terms dict from SortedSet/Sorted DocValues
> ----------------------------------------------------------------
>
> Key: LUCENE-9663
> URL: https://issues.apache.org/jira/browse/LUCENE-9663
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/codecs
> Reporter: Jaison.Bi
> Priority: Trivial
>
> Elasticsearch keyword field uses SortedSet DocValues. In our applications, “keyword” is the most frequently used field type.
> LUCENE-7081 has done prefix-compression for docvalues terms dict. We can do better by replacing prefix-compression with LZ4. In one of our application, the dvd files were ~41% smaller with this change(from 1.95 GB to 1.15 GB).
> I've done simple tests based on the real application data, comparing the write/merge time cost, and the on-disk *.dvd file size(after merge into 1 segment).
> || ||Before||After||
> |Write time cost(ms)|591972|618200|
> |Merge time cost(ms)|270661|294663|
> |*.dvd file size(GB)|1.95|1.15|
> This feature is only for the high-cardinality fields.
> I'm doing the benchmark test based on luceneutil. Will attach the report and patch after the test.
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