explain plan

[dunkin]

I ran a sql query in pl/sql developer, press F5, the optimizer goal is first_rows and the cost is 630K. I then copied that query to sqlplus client, set autotrace traceonly, the optimizer=first_rows, the cost is 12. How can the same query has different costs in diff. client?

 

[Marco Kalter]

The only possible reasons are:

1. Different query text
2. Different optimizer goal
3. Different tables/views
4. Different NLS settings