Fucun Chu created IMPALA-10463:
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Summary: 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
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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