Oracle Database Discussions

Hello,

I am trying to delete approximately 70,000 records from the table that contains total of 90,000 records....I am using the following sql statement;

delete from transaction where tx_id >18789;

tx_id (number) is my primary key for the table.

It takes approximately 1.5 hrs. to delete. Can anyone suggest reason why and possible solutions.
I am running oracle 9i release 2.

Thanks in advance.

Tejas.