Github user zentol commented on a diff in the pull request:
https://github.com/apache/flink/pull/1044#discussion_r37766532
--- Diff:
flink-java/src/main/java/org/apache/flink/api/java/operators/Keys.java ---
@@ -209,6 +209,9 @@ public ExpressionKeys(int[] groupingFields,
TypeInformation<T> type, boolean all
throw new InvalidProgramException("Specifying
keys via field positions is only valid " +
"for tuple data types. Type: "
+ type);
}
+ if (type.getArity() == 0) {
+ throw new InvalidProgramException("Tuple size
must be greater than 0. Size: " + type.getArity());
--- End diff --
this check was added specifically for Tuple0, as in the current code you'd
get weird exceptions when grouping on a Tuple0.
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