Here are some ways to improve delete query performance in Oracle:
1.DELETE statement with the WHERE clause: The DELETE statement with a WHERE clause is the most efficient way to delete rows from a table. The WHERE clause can be used to specify the conditions that must be met for a row to be deleted, which can reduce the number of rows that need to be deleted.
2.Batch processing: Instead of deleting all records in one large transaction, consider deleting records in smaller batches using a loop. This can help reduce the amount of undo and redo generated by the delete operation and improve performance.
Use COMMIT_INTERVAL parameter
3.Use the TRUNCATE statement: If you need to delete all records from a table, consider using the TRUNCATE statement instead of the DELETE statement. TRUNCATE is a faster operation because it does not generate undo and redo, and it resets the high-water mark of the table.
4.Disable indexes and constraints: If you have indexes or constraints on the table being deleted, consider disabling them temporarily during the delete operation. This can improve performance because the indexes and constraints do not need to be updated during the delete operation. Just remember to re-enable them once the delete operation is complete.
5.Partitioning: If the table being deleted is partitioned, consider using partitioning to delete only the partitions that need to be deleted. This can help reduce the amount of data that needs to be deleted and improve performance.
6.NOLOGGING option: If you do not need to recover the deleted data, consider using the NOLOGGING option during the delete operation. This can help reduce the amount of undo and redo generated by the delete operation and improve performance.
7.Parallel Processing: If your system has multiple CPUs, consider using parallel processing to delete the data. This can help divide the workload among the CPUs and improve performance.
By following these best practices, We should be able to improve delete performance in Oracle. However, it is important to test the performance of delete operation after implementing any of these optimizations to ensure that it is improving performance as expected.