Join Order Hints¶
The optimizer lists all join orders to choose the best one. What it does not do is an exhaustive search.
In case you believe a different join order to be useful, you can use one of the join order hints:
The latter is more versatile and should thus be preferred.
ORDERED takes no parameters and instructs the optimizer to join the tables in the order as they appear in the
ORDERED hint is so basic and you do not want to move around tables in the
FROM clause, Oracle has provided us with the
It takes the table names or aliases (if specified) as parameters, separated by spaces.
In the optimizer’s rock-paper-scissors game,
LEADING when both are specified for the same statement.
Moreover, if two or more conflicting
LEADING hints are provided, Oracle ignores all of them.
LEADING hints are thrown into the bin when they are incompatible with dependencies in the join graph.