Joined: 23 Nov 2006 Posts: 19270 Location: Inside the Matrix
If you are trying to select the max value of some non-key field (say an amount) and there are 100 million rows in the table, returning the MAX amount will surely impact performance. . .
If you are trying to select the max value of another amount field in a different table that has only 10 rows, there will be no performance impact. . .
The more work you cause the system to do, the greater the performance impact.
As i occasionally mention, when testing some new process/functionality, full-volume testing should be done well before deployment. Processes that run very well with almost no data often are not executable in the "real world". . .