Peformance of Functin in a procedure

Question

i have a proceudure which inserts data into a table using cursor
the select query of the cursor is having a function also
When i execute this procedure it is taking one hour to load 50000 rows
but the same select query of the procedure is giving me data in 40 secs
When i include the function inside my select query of the cursor it takes 5 mins to load 50000 rows
when i execute teh select query it is taking 1.5 mins
Please let me know whether the use of functin will affect the query to this extent(1 hour to 5 mins)

Answer 1

Iam not using any business logic
just inserting to the table
select empno,fget(empno) from emp--Execute in 20 secs
in Toad but in procedure it take 30 mins to insert
select empno,ename from emp--Execute in 1 min in Toad
but in procedure it take 3 mins to insertOk, ignore the Toad aspect of things, because Toad doesn't execute things in exactly the same way as plain old running SQL or PL/SQL through sql*plus.
In simple terms, what oracle has is two engines, one for SQL and the other for PL/SQL. If you write pure SQL using only "built in" functionality then your SQL is likely to perform well in comparison to using "user-defined" functions within it. If you call your own functions in an SQL query, then that function is called for each row of your data. Every time your function (PL/SQL remember) is called from SQL Oracle has to do what is called context switching. Context switching between the two engines is a major cause of performance problems.
Lesson: Don't use PL/SQL where the same can be achieved solely through SQL.