[jira] [Commented] (CALCITE-1472) Support CROSS/OUTER APPLY syntax

["Jark Wu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-1472?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15661186#comment-15661186 ] 

Jark Wu commented on CALCITE-1472:
----------------------------------

Hi [~julianhyde], sorry for the late response. Could we support MS SQL SERVER's syntax first ? Because SQL SERVER's syntax is simpler and only support table function which will be easy to implement I think. 

> Support CROSS/OUTER APPLY syntax
> --------------------------------
>
>                 Key: CALCITE-1472
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1472
>             Project: Calcite
>          Issue Type: New Feature
>            Reporter: Jark Wu
>            Assignee: Julian Hyde
>
> The CROSS/OUTER APPLY is very similar to CROSS JOIN and OUTER JOIN.  The difference is that the APPLY operator is used to invoke a table-valued function. This is not a standard SQL syntax , but introduced from MS SQL Server [1]. 
> The APPLY operator can be expressed by Calcite’s LATERAL TABLE . That means the 
> SELECT MyTable.*, t.s FROM MyTable CROSS APPLY split(MyTable.a)) AS t(s)
> corresponds to :
> SELECT MyTable.*, t.s FROM MyTable, LATERAL TABLE(split(MyTable.a)) AS t(s)
> and
> SELECT MyTable.*, t.s FROM MyTable OUTER APPLY split(MyTable.a)) AS t(s)
> corresponds to:
> SELECT MyTable.*, t.s FROM MyTable LEFT JOIN LATERAL TABLE(split(MyTable.a)) AS t(s)  ON TRUE
> The ON TRUE part is necessary for LEFT JOIN, but it's trivial for users. That's why I'm introducing "CROSS/OUTER APPLY" which will simplify the SQL a lot.
> As the APPLY can be expressed by LATERAL, so the only thing we need to touch is the Parser (see [2] and search FLINK to find the modification).  
> [1] https://technet.microsoft.com/en-us/library/ms175156(v=sql.105).aspx
> [2] https://github.com/wuchong/flink/blob/60812e51156ec9fa6088154d2f6dea8c1ff9ac17/flink-libraries/flink-table/src/main/codegen/templates/Parser.jj



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)