io.trino.sql.planner.iterative.rule.PushLimitThroughOffset 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.Capture;
import io.trino.matching.Captures;
import io.trino.matching.Pattern;
import io.trino.sql.planner.iterative.Rule;
import io.trino.sql.planner.plan.LimitNode;
import io.trino.sql.planner.plan.OffsetNode;
import static io.trino.matching.Capture.newCapture;
import static io.trino.sql.planner.plan.Patterns.limit;
import static io.trino.sql.planner.plan.Patterns.offset;
import static io.trino.sql.planner.plan.Patterns.source;
import static java.lang.Math.addExact;
/**
* Transforms:
*
* - Limit (row count x)
* - Offset (row count y)
*
* Into:
*
* - Offset (row count y)
* - Limit (row count x+y)
*
* Applies to both limit with ties and limit without ties.
*/
public class PushLimitThroughOffset
implements Rule
{
private static final Capture CHILD = newCapture();
private static final Pattern PATTERN = limit()
.with(source().matching(
offset().capturedAs(CHILD)));
@Override
public Pattern getPattern()
{
return PATTERN;
}
@Override
public Result apply(LimitNode parent, Captures captures, Context context)
{
OffsetNode child = captures.get(CHILD);
long count;
try {
count = addExact(parent.getCount(), child.getCount());
}
catch (ArithmeticException e) {
return Result.empty();
}
return Result.ofPlanNode(
child.replaceChildren(ImmutableList.of(
new LimitNode(
parent.getId(),
child.getSource(),
count,
parent.getTiesResolvingScheme(),
parent.isPartial(),
parent.getPreSortedInputs()))));
}
}