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https://issues.apache.org/jira/browse/PHOENIX-258?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Nick Dimiduk updated PHOENIX-258:
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Attachment: in-clause.png
Yes indeed. Here's a rudimentary test result -- my leading column has a total
cardinality of 7 values. These whisker plots show the query times when I do or
do not provide those 7 values via an 'in' clause. The query itself is a audit
kind of query, doing a group-by/count of events bucketed per hour. Providing
the values and thus informing the skip scanner makes for a noticeable
improvement in overall query time. I ran the queries 10 times each, alternating
between one than the other.
> Use skip scan when SELECT DISTINCT on leading row key column(s)
> ---------------------------------------------------------------
>
> Key: PHOENIX-258
> URL: https://issues.apache.org/jira/browse/PHOENIX-258
> Project: Phoenix
> Issue Type: Task
> Reporter: ryang-sfdc
> Labels: gsoc2016
> Fix For: 4.8.0
>
> Attachments: 258.txt, DistinctFixedPrefixFilter.java, in-clause.png
>
>
> 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.
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