Jark Wu created CALCITE-1472: -------------------------------- Summary: 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 Calciteās 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)