What are the different locking mechanisms in PostgreSQL?

What are the different locking mechanisms in PostgreSQL?

PostgreSQL uses several locking mechanisms, including row-level locks, table-level locks, and advisory locks. Row-level locks are used for individual rows during transactions, while table-level locks can lock entire tables. Advisory locks are user-defined and can be used for application-level locking.

Can you explain how row-level locks work?

Row-level locks in PostgreSQL prevent other transactions from modifying or deleting a row that is currently being modified. When a transaction updates a row, it acquires a lock on that row, ensuring that other transactions cannot change it until the first transaction is complete.

What happens if two transactions try to lock the same row?

If two transactions attempt to lock the same row, one will succeed and the other will be blocked until the first transaction is completed or rolled back. This ensures data integrity but can lead to deadlocks if not managed properly.

How can I avoid deadlocks in my application?

To avoid deadlocks, ensure that transactions acquire locks in a consistent order, keep transactions short, and use lower isolation levels when possible. Additionally, you can implement timeout settings to handle potential deadlocks.