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https://issues.apache.org/jira/browse/HIVE-1180?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13883553#comment-13883553
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Harish Butani commented on HIVE-1180:
-------------------------------------
As a first step have converted references to a CTE in the Query into a SubQuery
invocation.
This doesn't address the issue of materializing a CTE, which can then be used
in multiple parts of the Query.
But this issue exists for views today. For e.g. the following query:
{noformat}
create view v1 as
select key, min(value) as value
from src
group by key
;
explain
select a.key, b.key
from v1 a join v1 b on a.key = b.key;
{noformat}
Does the Group by on src twice.
Can we address the issue of materialization in a subsequent jira?
Have attached a preliminary patch.
> Support Common Table Expressions (CTEs) in Hive
> -----------------------------------------------
>
> Key: HIVE-1180
> URL: https://issues.apache.org/jira/browse/HIVE-1180
> Project: Hive
> Issue Type: Improvement
> Components: Query Processor
> Reporter: Jeff Hammerbacher
> Attachments: HIVE-1180.1.patch
>
>
> I've seen some presentations from the PostgreSQL recently expounding the
> utility of CTEs (http://en.wikipedia.org/wiki/Common_table_expressions).
> Should we try to support these in Hive? I've never used them in practice, so
> curious to hear if the community would find them useful.
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