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

To delete means to change the table's content. And this means, that after each deleted row all indexes must be updated and all foreign-key references must be checked. This can take a very long time!

Maybe this helps:

Make a copy of that table without any references, triggers and additional indexes. Then do this:

insert into new_table (field1, field2, ...) values (
    select field1, field2, ...
    from daily_au_by_service_summary 
    where summary_ts < to_date('09-04-2012','dd-mm-yyyy') 
);

If the fields in the tabels are defined in identical order, this might work too:

insert into new_table values (
    select *
    from daily_au_by_service_summary 
    where summary_ts < to_date('09-04-2012','dd-mm-yyyy') 
);

After that:

truncate daily_au_by_service_summary

and then:

insert into daily_au_by_service_summary (field1, field2, ...) values (
    select field1, field2, ...
    from new_table; 
);

New Table is not needed any longer:

drop new_table;