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From "Alicia Ying Shu (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (PHOENIX-1580) Support UNION ALL
Date Mon, 02 Mar 2015 00:30:05 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-1580?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14342556#comment-14342556
] 

Alicia Ying Shu edited comment on PHOENIX-1580 at 3/2/15 12:29 AM:
-------------------------------------------------------------------

[~maryannxue] Just to confim: "And as a result you will have to create a new RowProjector,
a single one for both side of the query." By this, you meant create a new RowProjector for
all the subSelects in the Union All query?

Just added TupleProjector alone would not work. As you later mentioned, you need to create
a temp table for it. It is exactly what I want to avoid since we do not need a temp table
for UNION ALL to eliminate duplicates. We can just stream the results. Not creating a temp
table has multiple advantages such as performance benefit and avoiding OutOfMemory issue.
Associating the RowProjector with ResultIterator can help stream the results without a temp
table. Let's make a decision on this. Thanks. [~jamestaylor]




was (Author: aliciashu):
[~maryannxue] Just to confim: "And as a result you will have to create a new RowProjector,
a single one for both side of the query." By this, you meant create a new RowProjector for
all the subSelects in the Union All query?

Just added TupleProjector alone would not work. As you later mentioned, you need to create
a temp table for it. It is exactly what I want to avoid since we do not need a temp table
for UNION ALL to eliminate duplicates. We can just stream the results. Not creating a temp
table has multiple advantages such as performance benefit and avoiding OutOfMemory issue.
But looks like with current architecture, it is easy to create a temp table before we project
the results in the client. 



> Support UNION ALL
> -----------------
>
>                 Key: PHOENIX-1580
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-1580
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: Alicia Ying Shu
>            Assignee: Alicia Ying Shu
>         Attachments: unionall-wipe.patch
>
>
> Select * from T1
> UNION ALL
> Select * from T2



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