What is explain in teradata?
The EXPLAIN facility is a teradata extension that provides you with an "ENGLISH" translation of the
steps chosen by the optimizer to execute an SQL statement. It may be used on any valid teradata database with a preface called "EXPLAIN".
The following is an example:-
EXPLAIN select last_name first_name FROM employees;
- The EXPLAIN parses the SQL statement but does not execute it.
- This provides the designer with an "execution strategy".
- The execution strategy provides what an optimizer does but not why it chooses them.
- The EXPLAIN facility is used to analyze all joins and complex queries.