Estimation of query execution time:
The SQL query execution is based on two factors. They are
1) Formation of Execution plan and
2) Execution of query based on that execution plan
So the query execution time is based on the above two factors. The query execution time is calculated by summation of time taken to form execution plan and time taken to execute the SQL query based on that execution plan.
The mathematically representation of query execution time:-
Query Execution time = SUM (Time Taken to form Execution plan, Time taken to execute the query based on that execution plan).
The performance of query is not only depends on the design of the SQL query. It depends on the execution plan also.
So we should pay attention on the design of effective execution plan also.
Innovative article but could have been more descriptive with examples.