"A. Kretschmer" <andreas.kretschmer@schollglas.com> writes:
> i expected for a 1000 row test-table a cost per function of 2.5
> (cpu_operator_cost = 0.0025), but i got 5.
What's the data type of "i"? I suspect you really have two function
calls in that expression: a type coercion function and cos() itself.
regards, tom lane