[CALCITE-6548] Return type of COVAR_SAMP, COVAR_POP and VAR_SAMP shou… #3935
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| @@ -1414,7 +1415,9 @@ private static RelDataType multivalentStringWithSepSumPrecision( | |||
| final RelDataType relDataType = | |||
| typeFactory.getTypeSystem().deriveCovarType(typeFactory, | |||
| opBinding.getOperandType(0), opBinding.getOperandType(1)); | |||
| if (opBinding.getGroupCount() == 0 || opBinding.hasFilter()) { | |||
| if (opBinding.getGroupCount() == 0 || opBinding.hasFilter() | |||
| || opBinding.getOperator().kind == SqlKind.COVAR_POP | |||
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are you sure about COVAR_POP?
Usually SAMP functions have the property that they return NULL for a non-empty set of size 1.
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According to https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/COVAR_POP.html. This function return type is nullable.
The function returns a value of type NUMBER. If the function is applied to an empty set, then it returns null.
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all aggregates return null when applied to an empty set.
but if getGroupCount() != 0 the set can never be empty (because then there would be no aggregate at all)
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this is about aggregates that are null even when the set is NOT empty
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empty set = set with all elements null
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I will do some test for this.
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…ld be nullable