io.trino.sql.planner.iterative.rule.RemoveRedundantJoin Maven / Gradle / Ivy
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.trino.sql.planner.iterative.rule;
import com.google.common.collect.ImmutableList;
import io.trino.matching.Captures;
import io.trino.matching.Pattern;
import io.trino.sql.planner.iterative.Lookup;
import io.trino.sql.planner.iterative.Rule;
import io.trino.sql.planner.plan.JoinNode;
import io.trino.sql.planner.plan.PlanNode;
import io.trino.sql.planner.plan.ValuesNode;
import static io.trino.sql.planner.optimizations.QueryCardinalityUtil.isEmpty;
import static io.trino.sql.planner.plan.Patterns.join;
public class RemoveRedundantJoin
implements Rule
{
private static final Pattern PATTERN = join();
@Override
public Pattern getPattern()
{
return PATTERN;
}
@Override
public Result apply(JoinNode node, Captures captures, Context context)
{
if (canRemoveJoin(node, context.getLookup())) {
return Result.ofPlanNode(
new ValuesNode(
context.getIdAllocator().getNextId(),
node.getOutputSymbols(),
ImmutableList.of()));
}
return Result.empty();
}
private boolean canRemoveJoin(JoinNode joinNode, Lookup lookup)
{
PlanNode left = joinNode.getLeft();
PlanNode right = joinNode.getRight();
return switch (joinNode.getType()) {
case INNER -> isEmpty(left, lookup) || isEmpty(right, lookup);
case LEFT -> isEmpty(left, lookup);
case RIGHT -> isEmpty(right, lookup);
case FULL -> isEmpty(left, lookup) && isEmpty(right, lookup);
};
}
}