[PHOENIX-258] Use skip scan when SELECT DISTINCT on leading row key column(s) - ASF JIRA

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create table(a varchar(32) not null, date date not null constraint pk primary key(a,date))

[["PLAN"],["CLIENT PARALLEL 94-WAY FULL SCAN OVER foo"],[" SERVER AGGREGATE INTO ORDERED DISTINCT ROWS BY [a]"],["CLIENT MERGE SORT"]]

We should skip scan.

duplicates

PHOENIX-2797 Ideas to speed up MIN/MAX/DISTINCT for prefixes of the PK

is related to

PHOENIX-3156 DistinctPrefixFilter optimization produces incorrect results with some non-pk WHERE conditions

1.	Use DistinctPrefixFilter logic for COUNT(DISTINCT ...) and COUNT(...) GROUP BY	Closed	Lars Hofhansl
2.	Some queries are misoptimized by PHOENIX-258	Closed	Lars Hofhansl
3.	DISTINCT/GROUP BY optimization not correct for null values in key parts	Closed	Lars Hofhansl
4.	Replace COUNT(DISTINCT...) with COUNT(...) when possible	Open	Unassigned
5.	Allow DistinctPrefixFilter optimization when HAVING clause only reference COUNT(DISTINCT)	Open	Unassigned
6.	Fixes for COUNT(DISTINCT...) with DistinctPrefixFilter and indexes	Closed	Lars Hofhansl
7.	DistinctPrefixFilter logic fails with local indexes and salted tables	Closed	Lars Hofhansl
8.	Refactor DistinctPrefixFilter as filter wrapper so that it can work with non-pk column filters.	Open	Unassigned
9.	COUNT(DISTINCT) may return null instead of 0 after PHOENIX-258	Closed	Lars Hofhansl
10.	Slight safety improvement for using DistinctPrefixFilter	Closed	Lars Hofhansl