Fix Float and Decimal coercion

Before the change, Float* and Decimal* would coerce to a decimal type.
However, decimal cannot store all the float values: different range,
NaN, and infinity. Coercing to floating point is more desirable and also
what other systems typically do.

datafusion/expr-common/src/type_coercion/binary.rs

@@ -928,9 +928,6 @@ fn coerce_numeric_type_to_decimal(numeric_type: &DataType) -> Option<DataType> {
         Int16 | UInt16 => Some(Decimal128(5, 0)),
         Int32 | UInt32 => Some(Decimal128(10, 0)),
         Int64 | UInt64 => Some(Decimal128(20, 0)),
-        // TODO if we convert the floating-point data to the decimal type, it maybe overflow.
-        Float32 => Some(Decimal128(14, 7)),
-        Float64 => Some(Decimal128(30, 15)),
         _ => None,
     }
 }
@@ -946,9 +943,6 @@ fn coerce_numeric_type_to_decimal256(numeric_type: &DataType) -> Option<DataType
         Int16 | UInt16 => Some(Decimal256(5, 0)),
         Int32 | UInt32 => Some(Decimal256(10, 0)),
         Int64 | UInt64 => Some(Decimal256(20, 0)),
-        // TODO if we convert the floating-point data to the decimal type, it maybe overflow.
-        Float32 => Some(Decimal256(14, 7)),
-        Float64 => Some(Decimal256(30, 15)),
         _ => None,
     }
 }

datafusion/sqllogictest/test_files/math.slt

@@ -694,3 +694,9 @@ select FACTORIAL(350943270);
 
 statement ok
 drop table signed_integers
+
+# Should not fail. The operands should coerce to float
+query B
+SELECT '1'::decimal(10,0) = '1e40'::double;
+----
+false

datafusion/sqllogictest/test_files/union.slt

@@ -836,3 +836,18 @@ physical_plan
 # Clean up after the test
 statement ok
 drop table aggregate_test_100;
+
+query T
+SELECT DISTINCT arrow_typeof(a) FROM (SELECT '1'::float UNION ALL SELECT '1'::decimal(10)) t(a)
+----
+Float32
+
+query T
+SELECT DISTINCT arrow_typeof(a) FROM (SELECT '1'::decimal(10) UNION ALL SELECT '1'::float ) t(a)
+----
+Float32
+
+query T
+SELECT DISTINCT arrow_typeof(a) FROM (SELECT '1'::decimal(10) UNION ALL SELECT '1'::double) t(a)
+----
+Float64