vtlim commented on code in PR #12710: URL: https://github.com/apache/druid/pull/12710#discussion_r910147202
########## docs/querying/sql.md: ########## @@ -185,20 +182,15 @@ UNION ALL SELECT COUNT(*) FROM tbl WHERE my_column = 'value2' ``` -With top-level UNION ALL, no further processing can be done after the UNION ALL. For example, the results of the -UNION ALL cannot have GROUP BY, ORDER BY, or any other operators applied to them. +> With top-level queries, you can't apply GROUP BY, ORDER BY, or any other operator to the results of a UNION ALL. ### Table-level -UNION ALL can be used to query multiple tables at the same time. In this case, it must appear in a subquery in the -FROM clause, and the lower-level subqueries that are inputs to the UNION ALL operator must be simple table SELECTs. -Features like expressions, column aliasing, JOIN, GROUP BY, ORDER BY, and so on cannot be used. The query will run -natively using a [union datasource](datasource.md#union). +In table-level queries, you must use UNION ALL in a subquery in the FROM clause, and create the lower-level subqueries that are inputs to the UNION ALL operator as simple table SELECTs. You can't use features like expressions, column aliasing, JOIN, GROUP BY, or ORDER BY. Review Comment: ```suggestion In table-level queries, you must use UNION ALL in a subquery in the FROM clause, and create the lower-level subqueries that are inputs to the UNION ALL operator as simple table SELECTs. You can't use features like expressions, column aliasing, JOIN, GROUP BY, or ORDER BY in table-level queries. ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
