public class SemiJoinRemoveRule extends RelOptRule
SemiJoins from a join tree.
It is invoked after attempts have been made to convert a SemiJoin to an indexed scan on a join factor have failed. Namely, if the join factor does not reduce to a single table that can be scanned using an index.
It should only be enabled if all SemiJoins in the plan are advisory; that is, they can be safely dropped without affecting the semantics of the query.
|Modifier and Type||Field||Description|
Creates a SemiJoinRemoveRule.
|Modifier and Type||Method||Description|
Receives notification about a rule match.
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
public static final SemiJoinRemoveRule INSTANCE
public SemiJoinRemoveRule(RelBuilderFactory relBuilderFactory)
public void onMatch(RelOptRuleCall call)
call.relsholds the set of relational expressions which match the operands to the rule;
call.relsis the root expression.
Typically a rule would check that the nodes are valid matches, creates
a new expression, then calls back
RelOptRuleCall.transformTo(org.apache.calcite.rel.RelNode, java.util.Map<org.apache.calcite.rel.RelNode, org.apache.calcite.rel.RelNode>) to
register the expression.
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