Deleting records with BLOB is very slow

Question

We have a Oracle 11g database with several different tables. One of the tables contains around 120,000 records and each record has a BLOB field. The data size in the BLOBs vary from 2-3KB to several MB. The problem is that when we want to delete a record from this table, it takes a long time - sometimes over a minute to delete just one record (using SQL developer or using a DBMS-job). We have no problem with deleting records of the other tables. For test purposes, we set the BLOB field of one record which we wanted to delete to EMPTY_BLOB(), but again deleting this record took a long time.

Is this behaviour normal for records containing BLOB? Is there any way to tune deleting such records so that they can be deleted a bit faster?

Answer 1

Thanks for the hints, specially the hint related to index. The problem was originated from lack of indexes on foreign keys. Actually, we had a "ON DELETE SET NULL" statement in foreign keys which were not indexed. When we indexed the foreign keys, the delete became very fast.