[jira] [Comment Edited] (PHOENIX-671) Support UNION

["James Taylor (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PHOENIX-671?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14258135#comment-14258135 ] 

James Taylor edited comment on PHOENIX-671 at 12/24/14 9:22 AM:
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Adding support for UNION would be pretty straightforward. Here's what would be required:
- Add support to PhoenixSQL.g for UNION. This would just be a select_statement followed by one or more ( UNION select_statement ).
- Modify QueryCompiler for the case of union to compile each individual select_statement through the standard QueryCompile method.
- Produce a RowProjector that is the union of all projected expressions across all select_statements.
- Produce a new UnionPlan which would pass in a List<QueryPlan> for the compilation of all other statements.
- Implement the iterator() method of UnionPlan to just instantiate a ConcatIterator which is the concatenation of all iterators from the List<QueryPlan> child plans.

In this case, the output would just be the concatenation of running all the select statements, one after the other, with a bit of intelligence in the formation of the RowProjector (which defines the "schema" of the tuples returned across all select statements).


was (Author: jamestaylor):
Adding support for UNION would be pretty straightforward. Here's what would be required:
- Add support to PhoenixSQL.g for UNION. This would just be a select_statement followed by one or more { UNION select_statement}.
- Modify QueryCompiler for the case of union to compile each individual select_statement through the standard QueryCompile method.
- Produce a RowProjector that is the union of all projected expressions across all select_statements.
- Produce a new UnionPlan which would pass in a List<QueryPlan> for the compilation of all other statements.
- Implement the iterator() method of UnionPlan to just instantiate a ConcatIterator which is the concatenation of all iterators from the List<QueryPlan> child plans.

In this case, the output would just be the concatenation of running all the select statements, one after the other, with a bit of intelligence in the formation of the RowProjector (which defines the "schema" of the tuples returned across all select statements).

> Support UNION
> -------------
>
>                 Key: PHOENIX-671
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-671
>             Project: Phoenix
>          Issue Type: Task
>            Reporter: James Taylor
>
> This is particularly useful for Pentaho support.



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