How to Compare 2 Hive Tables?

Nixon Data How to Compare 2 Hive Tables?

There are several ways you can compare two Hive tables to determine the differences between them. Here are a few options:

  • Use the EXCEPT operator: You can use the EXCEPT operator to compare the rows in two tables and return only the rows that are present in the first table but not in the second. For example:

SELECT * FROM table1
EXCEPT
SELECT * FROM table2;

  • Use the MINUS operator: You can use the MINUS operator, which is equivalent to the EXCEPT operator, to compare the rows in two tables and return only the rows that are present in the first table but not in the second. For example:

SELECT * FROM table1
MINUS
SELECT * FROM table2;

  • Use the NOT IN operator: You can use the NOT IN operator to compare the rows in two tables and return only the rows that are present in the first table but not in the second. For example:

SELECT * FROM table1
WHERE column1 NOT IN (SELECT column1 FROM table2);

  • Use the LEFT JOIN operator: You can use the LEFT JOIN operator to compare the rows in two tables and return all the rows from the left table (table1), along with any matching rows from the right table (table2). If there is no match, the right side will be filled with NULL values. For example:

SELECT * FROM table1
LEFT JOIN table2
ON table1.column1 = table2.column1;

  • You can then use the WHERE clause to filter out the rows where the values are the same in both tables. For example:

SELECT * FROM table1
LEFT JOIN table2
ON table1.column1 = table2.column1
WHERE table1.column2 <> table2.column2 OR table2.column2 IS NULL;

This will return all the rows from table1 that have different values in column2 compared to table2, or where there is no matching row in table2.