[
https://issues.apache.org/jira/browse/ARROW-6933?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
ASF GitHub Bot updated ARROW-6933:
----------------------------------
Labels: pull-request-available (was: )
> [Java] Suppor linear dictionary encoder
> ---------------------------------------
>
> Key: ARROW-6933
> URL: https://issues.apache.org/jira/browse/ARROW-6933
> Project: Apache Arrow
> Issue Type: New Feature
> Components: Java
> Reporter: Liya Fan
> Assignee: Liya Fan
> Priority: Major
> Labels: pull-request-available
>
> For many scenarios, the distribution of dictionary entries is highly skewed.
> In other words, a few dictionary entries occurs much more frequently than
> others. If we can sort the dictionary by the non-increasing order of entry
> frequencies, and compare each value to encode from the beginning of the
> dictionary, we get the following benefits:
> 1) We need no extra memory space or data structure.
> 2) The search is extremely efficient, as we are likely to find a match
> in the first few entries of the dictionary.
> This is the basic idea behind the linear dictionary encoder. When the
> scenario is right (highly skewed dictionary distribution), it outperforms
> both search based encoder and hash table based encoders.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
