Hive : A Deep Dive into ‘AUTOCOMMIT’ in Apache Hive

Hive provides many functionalities to ensure efficient and seamless data management, with ‘AUTOCOMMIT’ being one such feature that plays an important role in transaction management.

What is AUTOCOMMIT in Hive?

The ‘AUTOCOMMIT’ property in a database system, including Hive, is a feature that allows the system to automatically commit each individual SQL statement as a transaction. When AUTOCOMMIT is set to true, each SQL statement is treated as a transaction and will be automatically committed right after it is executed.

Apache Hive, however, has a slightly different behavior due to its inherent design. As of my knowledge cutoff in September 2021, Apache Hive does not support AUTOCOMMIT functionality in the same way that traditional RDBMSs like MySQL do. Transactions in Hive need to be managed explicitly using START TRANSACTION, COMMIT, and ROLLBACK commands.

When to Use AUTOCOMMIT?

Although Hive does not support AUTOCOMMIT in a traditional sense, understanding when to use it (in systems that support it) is crucial. AUTOCOMMIT is often used when the SQL statements are standalone, and you want to ensure that each SQL statement gets committed right after its execution. This removes the need to manually issue a COMMIT statement after each operation, making it simpler and less error-prone.

Conversions Available

As mentioned earlier, Hive does not directly support the AUTOCOMMIT property. However, you can emulate the behavior by explicitly issuing COMMIT after each operation.

Example DDL + INSERT and Commit Use

Below is an example of creating a table, inserting data, and committing the transaction to simulate the behavior of AUTOCOMMIT.

-- Create table
CREATE TABLE IF NOT EXISTS employees (
  id INT,
  name STRING,
  department STRING
) CLUSTERED BY(id) INTO 3 BUCKETS STORED AS ORC TBLPROPERTIES('transactional'='true');

-- Start transaction, insert data, and commit
START TRANSACTION;
INSERT INTO TABLE employees (id, name, department)
VALUES (1, 'Sachin', 'Sales');
COMMIT;  -- Commit after each operation to emulate AUTOCOMMIT

-- Repeat for next set of data
START TRANSACTION;
INSERT INTO TABLE employees (id, name, department)
VALUES (2, 'Rajesh', 'Marketing');
COMMIT;