Should You Manually Close Cursors in MySQLdb?

Best Practices for Managing Cursors in MySQLdb

Overview

MySQLdb, a popular Python package for interacting with MySQL databases, emulates cursors for accessing results and executing queries. However, understanding when to close these cursors and the optimal practices surrounding their usage is crucial for efficient database management.

Standard Practices

Rather than relying on perceived standard practices, it's advisable to consult the MySQLdb module documentation for guidance. As of version 1.2.5, the module implements the context manager protocol for transaction handling, but it does not mandate cursor closure.

Using the 'with' Construct

The 'with' keyword provides a convenient way to manage connections and cursors within a specific code block. However, it's important to note that using 'with' does not explicitly close the cursor or the connection. Both remain open after exiting the 'with' block.

cursor.close() vs. connection.commit()

Contrary to some assumptions, the cursor.close() method is not called automatically after connection.commit(). MySQLdb's MySQL C API implementation does not require cursor closure before commits.

Optimizing Cursor Usage

The overhead of creating new cursors is negligible. It's typically not a concern and does not require seeking out specific transactions to avoid cursor creation.

When to Close Cursors

A general rule of thumb is to close cursors when they are no longer needed. However, in the case of MySQLdb, cursors will be automatically closed once they go out of scope or when all references to them are removed. Nonetheless, manually closing cursors can provide clarity and avoid potential issues arising from abandoned connections.

Using contextlib.closing

For scenarios where automatic cursor closure is desired within a 'with' statement, the contextlib.closing context manager can be used to explicitly close the cursor after the block's execution. However, it's essential to understand the potential implications related to transactions and connection objects when utilizing this approach.

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