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https://issues.apache.org/jira/browse/PHOENIX-153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16061645#comment-16061645
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Ethan Wang commented on PHOENIX-153:
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+1. After some study about _calcite/parse.jj_ and
_calcite/SqlValidatorFeatureTest.java_, my understanding is that calcite seems
to be very close to Postgres TABLESAMPLE syntax (which PHOENIX-153 is also
designed to be similar with).
I'd like to sum up two differences below (please correct me if I'm mistaken
[~julianhyde]).
1, Calcite table sampling rate input is 0 to 100 (PHOENIX-153 currently is 0 to
1).
2, Syntax difference
Calcite: select name from dept TABLESAMPLE system(58)
PHOENIX-153: select name from dept TABLESAMPLE 0.58
Purposing change for PHOENIX-153: Let's change phoenix side to be
select name from dept TABLESAMPLE(0.58)
Thoughts?
Reference:
https://github.com/apache/calcite/blob/d619304070bf2874ab760c92ec2573ee6c19f536/piglet/src/main/javacc/PigletParser.jj
https://github.com/apache/calcite/blob/0938c7b6d767e3242874d87a30d9112512d9243a/core/src/test/java/org/apache/calcite/test/SqlValidatorFeatureTest.java
> Implement TABLESAMPLE clause
> ----------------------------
>
> Key: PHOENIX-153
> URL: https://issues.apache.org/jira/browse/PHOENIX-153
> Project: Phoenix
> Issue Type: Task
> Reporter: James Taylor
> Assignee: Ethan Wang
> Labels: enhancement
>
> Support the standard SQL TABLESAMPLE clause by implementing a filter that
> uses a skip next hint based on the region boundaries of the table to only
> return n rows per region.
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