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https://issues.apache.org/jira/browse/LUCENE-9663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17263831#comment-17263831
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Jaison.Bi commented on LUCENE-9663:
-----------------------------------
Thanks for the comment, [~sokolov]
{quote}if you are running luceneutil tests, could you please also report QPS
changes?
{quote}
Sure, I will.
{quote}I'm not clear what the usage of this {{keywords}} field is exactly - is
it used for aggregations?
{quote}
Ya, "keyword" field is used for aggregations mostly.
{quote}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.
{quote}
ok, I will learn how to change luceneutil. Meanwhile, I can do another
benchmark test using *esrally* as a supplement, it has some aggregation tests.
would it be alright?
Actually, aggregations are using *global ordinal data* instead of terms dict,
terms dict compression will affect the performance of building global oridinal
data. Anyway, I will test the impact on query side.
> 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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