[GitHub] spark pull request #17236: [SPARK-19893][SQL] Cannot run intersect/except wi...

[hvanhovell <gi...@git.apache.org>]

Github user hvanhovell commented on a diff in the pull request:

    https://github.com/apache/spark/pull/17236#discussion_r105351724
  
    --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala ---
    @@ -319,7 +322,7 @@ trait CheckAnalysis extends PredicateHelper {
                   // Check if the data types match.
                   dataTypes(child).zip(ref).zipWithIndex.foreach { case ((dt1, dt2), ci) =>
                     // SPARK-18058: we shall not care about the nullability of columns
    -                if (TypeCoercion.findWiderTypeForTwo(dt1.asNullable, dt2.asNullable).isEmpty) {
    +                if (!dt1.sameType(dt2)) {
    --- End diff --
    
    We shouldn't change this. This makes sure we generate the correct error message for union. The problem is that an earlier pair of columns might not be the same but castable, while a later pair column is not the same and we can't cast them; the error should show the latter pair of columns and not the first one (which happens if we revert this).


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