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https://issues.apache.org/jira/browse/IMPALA-4025?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16489475#comment-16489475
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ASF subversion and git services commented on IMPALA-4025:
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Commit 1ca077fd065bc5689e7614073c174b5a2bb11d96 in impala's branch
refs/heads/master from [~tianyiwang]
[ https://git-wip-us.apache.org/repos/asf?p=impala.git;h=1ca077f ]
IMPALA-4025: Part 1: Generalize and cleanup StmtRewriter
This patch generalizes StmtRewriter, allowing it to be subclassed. The
base class would traverse the stmt tree while the subclasses can install
hooks to execute specific rewrite rules at certain places. Existing
rewriting rules are moved into SubqueryRewriter.
Change-Id: I9e7a6108d3d49be12ae032fdb54b5c3c23152a47
Reviewed-on: http://gerrit.cloudera.org:8080/10495
Reviewed-by: Vuk Ercegovac <[email protected]>
Tested-by: Impala Public Jenkins <[email protected]>
> add functions PERCENTILE_DISC(), PERCENTILE_CONT(), and MEDIAN()
> ----------------------------------------------------------------
>
> Key: IMPALA-4025
> URL: https://issues.apache.org/jira/browse/IMPALA-4025
> Project: IMPALA
> Issue Type: New Feature
> Components: Backend, Frontend
> Affects Versions: Impala 2.2.4
> Reporter: Greg Rahn
> Assignee: Tianyi Wang
> Priority: Major
> Labels: built-in-function, sql-language
>
> Add the following functions as both an aggregate function and window/analytic
> function:
> * PERCENTILE_CONT
> * PERCENTILE_DISC
> * MEDIAN (impmented as PERCENTILE_CONT(0.5))
> h6. Syntax
> {code}
> PERCENTILE_CONT(<percentile>) WITHIN GROUP (ORDER BY <expression> [ASC|DESC]
> [NULLS {FIRST | LAST}]) [ OVER ([<window-partition-clause>])]
> PERCENTILE_DISC(<percentile>) WITHIN GROUP (ORDER BY <expression> [ASC|DESC]
> [NULLS {FIRST | LAST}]) [ OVER ([<window-partition-clause>])]
> MEDIAN(expr) [ OVER (<window-partition-clause>) ]
> {code}
> h6. Notes from other systems
> *Greenplum*
> {code}
> PERCENTILE_CONT(_percentage_) WITHIN GROUP (ORDER BY _expression_)
> {code}
> http://gpdb.docs.pivotal.io/4320/admin_guide/query.html
> Greenplum Database provides the MEDIAN aggregate function, which returns the
> fiftieth percentile of the PERCENTILE_CONT result and special aggregate
> expressions for inverse distribution functions as follows:
> Currently you can use only these two expressions with the keyword WITHIN
> GROUP.
> Note: aggregation fuction only
> *Oracle*
> {code}
> PERCENTILE_CONT(expr) WITHIN GROUP (ORDER BY expr [ DESC | ASC ]) [ OVER
> (query_partition_clause) ]}}
> {code}
> http://docs.oracle.com/database/121/SQLRF/functions141.htm#SQLRF00687
> Note: implemented as both an aggregate and window function
> *Vertica*
> {code}
> PERCENTILE_CONT ( %_number ) WITHIN GROUP (... ORDER BY expression [ ASC |
> DESC ] ) OVER (... [ window-partition-clause ] )
> {code}
> https://my.vertica.com/docs/7.2.x/HTML/index.htm#Authoring/SQLReferenceManual/Functions/Analytic/PERCENTILE_CONTAnalytic.htm
> Note: window fuction only
> *Teradata*
> {code}
> PERCENTILE_CONT(<value_expression>) WITHIN GROUP (ORDER BY <value_expression>
> [asc | desc] [nulls {first | last}])
> {code}
> Note: aggregation fuction only
> *Netezza*
> {code}
> SELECT fn(<expr>) WITHIN GROUP (ORDER BY <value_expression> [asc|desc] [nulls
> {first | last}]) FROM <from_expr>[GROUP BY <group_expr>];
> {code}
> https://www.ibm.com/support/knowledgecenter/SSULQD_7.2.1/com.ibm.nz.dbu.doc/c_dbuser_inverse_distribution_funcs_family_syntax.html
> Note: aggregation fuction only
> *Redshift*
> {code}
> PERCENTILE_CONT ( percentile ) WITHIN GROUP (ORDER BY expr) OVER ( [
> PARTITION BY expr_list ] )
> {code}
> https://www.ibm.com/support/knowledgecenter/SSULQD_7.2.1/com.ibm.nz.dbu.doc/c_dbuser_inverse_distribution_funcs_family_syntax.html
> Note: window fuction only
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