xiedeyantu commented on code in PR #21362: URL: https://github.com/apache/datafusion/pull/21362#discussion_r3067906920
########## datafusion/sqllogictest/test_files/order.slt: ########## @@ -1521,7 +1579,7 @@ query TT EXPLAIN SELECT c1, c2 FROM table_with_ordered_pk ORDER BY c1, c2; ---- logical_plan -01)Sort: table_with_ordered_pk.c1 ASC NULLS LAST, table_with_ordered_pk.c2 ASC NULLS LAST +01)Sort: table_with_ordered_pk.c1 ASC NULLS LAST Review Comment: @alamb I fully agree with Neil's explanation: functional dependency serves precisely to guarantee this property—for instance, an injective function inherently exhibits the characteristics of functional dependency. In the context of `ORDER BY`, an additional aspect of ordering comes into play, requiring evaluation based on the sequence of the original fields (as explained in the accompanying code); this ensures that the semantics remain correct after the `ORDER BY` fields have been eliminated. -- 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]
