dbatomic commented on code in PR #45383: URL: https://github.com/apache/spark/pull/45383#discussion_r1519587302
########## sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TypeCoercion.scala: ########## @@ -764,6 +773,94 @@ abstract class TypeCoercionBase { } } + object CollationTypeCasts extends TypeCoercionRule { + override def transform: PartialFunction[Expression, Expression] = { + case e if !e.childrenResolved => e + + case b @ BinaryComparison(left, right) if shouldCast(Seq(left.dataType, right.dataType)) => + val newChildren = collateToSingleType(Seq(left, right)) + b.withNewChildren(newChildren) + } + + def shouldCast(types: Seq[DataType]): Boolean = { + types.forall(_.isInstanceOf[StringType]) && types.distinct.length > 1 + } + + /** + * Collates the input expressions to a single collation. + */ + def collateToSingleType(exprs: Seq[Expression]): Seq[Expression] = { + val collationId = getOutputCollation(exprs) + + exprs.map { expression => + expression.dataType match { + case st: StringType if st.collationId == collationId => + expression + case _: StringType => + Cast(expression, StringType(collationId)) + } + } + } + + /** + * Based on the data types of the input expressions this method determines + * a collation type which the output will have. + */ + def getOutputCollation(exprs: Seq[Expression], failOnIndeterminate: Boolean = true): Int = { + val explicitTypes = exprs.filter(hasExplicitCollation).map(_.dataType).distinct Review Comment: Again, check collation id explicitly. -- 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: reviews-unsubscr...@spark.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org