[jira] [Issue Comment Deleted] (TRAFODION-1673) Implement the WITH clause in Trafodion SQL for simple use cases

["liu ming (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TRAFODION-1673?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

liu ming updated TRAFODION-1673:
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    Comment: was deleted

(was: It can be first implemented using sub-query, that is, to replace each WITH clause by a sub query. (RenamedTable)

CTE mentioned by QiFan is a great idea, and we can set it as a final goal. To meet the functional requirement, we can simply use subquery in the first iteration.)

> Implement the WITH clause in Trafodion SQL for simple use cases
> ---------------------------------------------------------------
>
>                 Key: TRAFODION-1673
>                 URL: https://issues.apache.org/jira/browse/TRAFODION-1673
>             Project: Apache Trafodion
>          Issue Type: New Feature
>          Components: sql-cmp
>            Reporter: Hans Zeller
>            Assignee: liu ming
>
> We keep running into queries that use a WITH clause to define a temporary view that can be used once or multiple times in a FROM clause in the query.
> For non-recursive queries, the WITH clause could probably be handled very similar to a view. When it is defined, we create an in-memory view descriptor, containing the name and the definition. When it is used in a FROM clause, we could go through a code path similar to that of a view - bind the (temporary) view text and substitute it in the query. The fix could probably be handled entirely in the binder.
> This JIRA is *not* about recursive queries, those would require a lot more effort, involving many components in addition to the binder.



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