Delete statement was very slow in Oracle

Question

I have a table with about 100k records and I want to delete some rows, The problem is that the DELETE statement is running very slowly - it didn\'t finish in 30 min

Answer 1

There can be many reasons:

• Server load (unlikely because the SELECT is fast)
• Triggers (see here how to list them for a table).
• Foreign keys (List of foreign keys and the tables they reference)
• A lot of data in each row (LOBs, many columns).
• Someone is locking rows in the table that you'd like to delete (or the whole table). See this blog post how to list locks. This discussion might also help.

If the foreign keys are the problem, the usual solution is to add indexes on the foreign column: For each delete, Oracle needs to check whether this would violate a foreign key relation.