Tips and Tricks to perform Bulk deletion in PostgreSQL - shiviyer/Blogs GitHub Wiki

Performing bulk deletion in PostgreSQL can be achieved through the following steps:

1. Use DELETE Statement: For small to medium-sized tables, you can simply use the DELETE FROM table_name WHERE condition; statement. However, this method can be inefficient for large tables due to the high I/O and CPU load.

2. Delete Batches: For larger tables, delete in batches to avoid long-running transactions and reduce lock contention. This involves using a loop in a PL/pgSQL function or a script to delete a fixed number of rows at a time.

3. Use TRUNCATE for Full Deletion: If you need to remove all rows from a table, TRUNCATE table_name; is much faster than DELETE. It effectively drops and recreates the table.

4. Drop and Recreate for Massive Tables: For very large tables, it might be more efficient to create a new table with the desired data and drop the old one. This approach is often faster but requires additional disk space and careful handling to maintain data integrity.

5. Consider Indexes and Constraints: Bulk deletion can be slow if the table has many indexes or foreign key constraints. You may choose to temporarily drop indexes and constraints and recreate them after the deletion.

6. Vacuuming: After bulk deletion, it's advisable to run VACUUM FULL on the table to reclaim space and reorganize it for efficiency.

Remember to backup important data before performing bulk deletions and test your approach in a non-production environment to ensure it meets your needs without causing issues.