Difference between DELETE and TRUNCATE commands in PostgreSQL

DELETE command in PostgreSQL is used to remove specific rows from a table based on a condition, while TRUNCATE command is used to remove all rows from a table in a faster and more efficient way.

When using DELETE, the operation is logged in the transaction log and each row is deleted individually which might slow down the process for large tables. On the other hand, TRUNCATE removes all rows at once without logging each row deletion, making it faster but it resets the sequence identifiers.

It is important to note that DELETE can be rolled back, while TRUNCATE cannot be undone. Additionally, DELETE triggers BEFORE and AFTER row-level triggers, while TRUNCATE does not fire any triggers.

Overall, DELETE is more suitable for removing specific rows with caution and control, while TRUNCATE is better suited for quickly clearing out entire tables without the need for a lot of logging.