[IMPALA-10131] Document ds_kll_* functions

• Type: New Feature
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Impala 4.0.0
• Component/s: Docs
• Labels: doc
• Epic Link: unlabelled-IMPALA-9594
• Epic Color: ghx-label-8
• Assignee: Unassigned
• Reporter: Adam Tamas
• Created: 02/Sep/20 12:09
• Updated: 02/Sep/20 12:09

Description

There were some new functions added recently to add support for Apache DataSketches KLL calculations. These functions purpose is to give an approximate boundaries for
a given dataset. It is an implementation of a very compact quantiles sketch with lazy compaction scheme and nearly optimal accuracy per bit.

The newly introduced functions are:
ds_kll_sketch()
ds_kll_quantile()
ds_kll_quantiles_as_string()
ds_kll_n()
ds_kll_union()
ds_kll_rank()
ds_kll_pmf_as_string()
ds_kll_cdf_as_string()
ds_kll_stringify()

Related Jiras:
https://issues.apache.org/jira/browse/IMPALA-9959
https://issues.apache.org/jira/browse/IMPALA-9962
https://issues.apache.org/jira/browse/IMPALA-9963
https://issues.apache.org/jira/browse/IMPALA-10017
https://issues.apache.org/jira/browse/IMPALA-10018
https://issues.apache.org/jira/browse/IMPALA-10019
https://issues.apache.org/jira/browse/IMPALA-10020
https://issues.apache.org/jira/browse/IMPALA-10108

We should document these and mark them as experimental features so that users can try out and hopefully give feedback.