这个 = 以及 == 运算符具有相同的功能。
它们由完全相同的类实现。

system.registerGenericUDF("=", GenericUDFOPEqual.class);
system.registerGenericUDF("==", GenericUDFOPEqual.class);

函数注册表.java

+----------+---------------------+----------------------------------------------------------------+
| Operator |    Operand types    |                          Description                           |
+----------+---------------------+----------------------------------------------------------------+
| A = B    | All primitive types | TRUE if expression A is equal to expression B otherwise FALSE. |
| A == B   | All primitive types | Synonym for the = operator.                                    |
+----------+---------------------+----------------------------------------------------------------+

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