phoenix-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Gerald Sangudi (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (PHOENIX-4618) Optimize out order-by on sort-merge-join when possible
Date Mon, 18 Mar 2019 16:15:00 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-4618?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16795156#comment-16795156
] 

Gerald Sangudi edited comment on PHOENIX-4618 at 3/18/19 4:14 PM:
------------------------------------------------------------------

Does this change work with various forms of GROUP BY?

E.g. hash grouping or */** HASH_AGGREGATE **/* hint?


was (Author: sangudi):
Does this change work with various forms of GROUP BY?

E.g. hash grouping or */* HASH_AGGREGATE */* hint?

> Optimize out order-by on sort-merge-join when possible
> ------------------------------------------------------
>
>                 Key: PHOENIX-4618
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4618
>             Project: Phoenix
>          Issue Type: Improvement
>            Reporter: Maryann Xue
>            Assignee: Maryann Xue
>            Priority: Major
>             Fix For: 4.15.0
>
>
> To do this, \{{OrderPreservingTracker}} relies solely on primary keys for inferring alignment
between order-by expressions and the input sortedness. To implement this improvement, we
need to have extra information of sortedness which supports equivalent sorted expressions.
For example,
> {code}SELECT * FROM T1 JOIN T2 ON T1.a = T2.a and T1.b = T2.b{code}
> The result of the sort-merge-join is sorted on (T1.a, T1.b) and (T2.a, T2.b) at the same
time.
> Thus, both 1)
> {code}SELECT * FROM T1 JOIN T2 ON T1.a = T2.a and T1.b = T2.b ORDER BY T1.a, T1.b{code}
> and 2)
> {code}SELECT * FROM T1 JOIN T2 ON T1.a = T2.a and T1.b = T2.b ORDER BY T2.a, T2.b{code}
> should avoid doing an extra order-by after the sort-merge-join operation.



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)

Mime
View raw message