LEFT_CARDINALITY (JOIN Option)

LEFT_CARDINALITY provides a cardinality hint for the left-hand side (LHS) of a join. The optimizer uses this option’s value as a hint to help choose a better query execution plan.

If LEFT_CARDINALITY is not specified, the optimizer relies on statistics processing for cardinality estimates.

Operator

JOIN

Syntax

LEFT_CARDINALITY=<int>

The <int> argument specifies the cardinality value to use for the left-hand side.

Example

SELECT column1 FROM table1 INNER {OPTION LEFT_CARDINALITY=10} 

	JOIN table2 ON table1.id = table2.id