Github user cloud-fan commented on a diff in the pull request: https://github.com/apache/spark/pull/17185#discussion_r207759811 --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/package.scala --- @@ -169,25 +181,50 @@ package object expressions { }) } - // Find matches for the given name assuming that the 1st part is a qualifier (i.e. table name, - // alias, or subquery alias) and the 2nd part is the actual name. This returns a tuple of + // Find matches for the given name assuming that the 1st two parts are qualifier + // (i.e. database name and table name) and the 3rd part is the actual column name. + // + // For example, consider an example where "db1" is the database name, "a" is the table name + // and "b" is the column name and "c" is the struct field name. + // If the name parts is db1.a.b.c, then Attribute will match --- End diff -- What I'm talking about is ambiguity. `col.innerField1.innerField2` can fail if the `innerField2` doesn't exist. My question is: shall we try all the possible resolution paths and pick the valid one, or define a rule that we can decide the resolution path ahead.
--- --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org