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Posted to issues-all@impala.apache.org by "Fucun Chu (Jira)" <ji...@apache.org> on 2021/05/06 01:33:00 UTC
[jira] [Commented] (IMPALA-10282) Implement ds_cpc_sketch() and
ds_cpc_estimate() functions
[ https://issues.apache.org/jira/browse/IMPALA-10282?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17339957#comment-17339957 ]
Fucun Chu commented on IMPALA-10282:
------------------------------------
https://gerrit.cloudera.org/#/c/16656/ review
> Implement ds_cpc_sketch() and ds_cpc_estimate() functions
> ----------------------------------------------------------
>
> Key: IMPALA-10282
> URL: https://issues.apache.org/jira/browse/IMPALA-10282
> Project: IMPALA
> Issue Type: New Feature
> Components: Backend, Frontend
> Reporter: Fucun Chu
> Assignee: Fucun Chu
> Priority: Major
>
> These should be built-in functions that use DataSketches functionality that was integrated by IMPALA-10279.
> ds_cpc_sketch() should receive a primitive expression and return a sketch in string type (or binary once that work is submitted).
> ds_cpc_estimate() should receive a sketch and return an estimate of unique count from a given CpcSketch.
> Usage:
> select ds_cpc_estimate(ds_cpc_sketch(col_name)) from table_name;
> Hive change that introduced the same:
> https://issues.apache.org/jira/browse/HIVE-22940
> Some further examples found here:
> [http://datasketches.apache.org/docs/CPC/CpcCppExample.html]
>
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