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Posted to issues@impala.apache.org by "Fucun Chu (Jira)" <ji...@apache.org> on 2021/02/19 14:06:00 UTC
[jira] [Resolved] (IMPALA-10463) Implement ds_theta_sketch() and
ds_theta_estimate() functions
[ https://issues.apache.org/jira/browse/IMPALA-10463?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Fucun Chu resolved IMPALA-10463.
--------------------------------
Resolution: Fixed
> Implement ds_theta_sketch() and ds_theta_estimate() functions
> -------------------------------------------------------------
>
> Key: IMPALA-10463
> URL: https://issues.apache.org/jira/browse/IMPALA-10463
> Project: IMPALA
> Issue Type: New Feature
> Components: Backend, Frontend
> Reporter: Fucun Chu
> Assignee: Fucun Chu
> Priority: Major
> Fix For: Impala 4.0
>
>
> These should be built-in functions that use DataSketches functionality that was integrated by [IMPALA-10440|https://issues.apache.org/jira/browse/IMPALA-10440].
> ds_theta_sketch() should receive a primitive expression and return a sketch.ds_theta_estimate() should receive a sketch and return a primitive that is the cardinality estimate for that set of data provided to the sketch.
> Usage:
> select ds_theta_estimate(ds_theta_sketch(col_name)) from table_name;Returns a cardinality estimate for that particular column.
> Hive change that introduced the same: https://issues.apache.org/jira/browse/HIVE-22940
> [https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/exec/DataSketchesFunctions.java]
>
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