[GitHub] [calcite] chunweilei commented on a change in pull request #1611: [CALCITE-3355] Deduce whether CASE and COALESCE may produce NULL values

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chunweilei commented on a change in pull request #1611: [CALCITE-3355] Deduce 
whether CASE and COALESCE may produce NULL values
URL: https://github.com/apache/calcite/pull/1611#discussion_r353046030
 
 

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 File path: core/src/test/java/org/apache/calcite/test/SqlValidatorTest.java
 ##########
 @@ -619,6 +625,9 @@ private static String 
cannotStreamResultsForNonStreamingInputs(String inputs) {
     expr("coalesce('a','b')").ok();
     expr("coalesce('a','b','c')")
         .columnType("CHAR(1) NOT NULL");
+
+    sql("select COALESCE(mgr, 12) as m from EMP")
 
 Review comment:
   IMO, we cannot deduce whether `NULLIF(x, -1)` is nullable or not when 
validating since we don't know whether `x` equals `1` or not.  Besides, there 
is already some test for it[1].
   
   [1] 
https://github.com/apache/calcite/blob/master/core/src/test/java/org/apache/calcite/test/SqlValidatorTest.java#L603

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