Hive Semantic Analysis Exception: Expect Equality Expression for Join Condition

This exception occurs when you use inequality expressions (e.g., '<', '>', '<=', '>=', '<>') in the join condition without using the MapJoin hint. To resolve this, you can either use the MapJoin hint or modify the join condition to only use equality expressions (i.e., only use '=' and 'AND'). Here are two solutions:

1. Use the MapJoin Hint:

   Add the MapJoin hint to your join query to tell Hive to use the MapJoin algorithm for the join operation. For example:

   SELECT /*+ MAPJOIN(t2) */ t1.id, t2.name
   FROM table1 t1 JOIN table2 t2 ON t1.id = t2.id;
   

   Note: Using the MapJoin hint can lead to higher memory consumption, so use it with caution, especially if your datasets are large.

2. Modify the Join Condition:

   If using the MapJoin hint is not an option, you can modify the join condition to only use equality expressions. For example, you can rewrite an inequality expression as an equality expression:

   SELECT t1.id, t2.name
   FROM table1 t1 JOIN table2 t2 ON t1.id = t2.id AND t1.age = t2.age;
   

   Rewriting inequality expressions as equality expressions ensures the correctness of your join query and prevents the exception.