Delete statements very slow

Question

hi,
We have a performance issue the delete statements on the database are running very slow they are taking about 12 hours.
the delete statements are like
DELETE table_name
WHERE column1 = 'temp'
AND col2 LIKE 'A%'
AND col3 = 0;
that table has an composite index with 5 columns and the columns specified in the delete statements are in the order
column1 position 4
col2 position 3
col3 position 5
no additional indexes are present on the table

Answer 1

As already suggested get an execution plan for the deletes to see what it is doing to make informed decisions about what to do.
Until then ...
You said you have one index on 5 columns
WHERE column1 = 'temp'
AND col2 LIKE 'A%'
AND col3 = 0;
that table has an composite index with 5 columns and the columns specified in the delete statements are in the order
column1 position 4
col2 position 3
col3 position 5Oracle might be doing a skip scan on the index or a full table scan - it is possible neither is efficient for your operation. An index ordered by # of unique values (most unique first) on column1, col2, col3 might help performance on this delete if a small percentage of rows are being deleted (anywhere from 5% to maybe 30%, it depends). If a large percentage of rows are being deleted then a full table scan might be better.
If you have the license and the database is set up for it parallel DML is a possiblity - check the on-line documentation to see how to do the delete in parallel.