io.trino.sql.planner.iterative.rule.RemoveEmptyGlobalAggregation 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 io.trino.matching.Captures;
import io.trino.matching.Pattern;
import io.trino.sql.planner.iterative.Rule;
import io.trino.sql.planner.plan.AggregationNode;
import io.trino.sql.planner.plan.ValuesNode;
import static com.google.common.base.Preconditions.checkArgument;
import static io.trino.sql.planner.plan.Patterns.Aggregation.step;
import static io.trino.sql.planner.plan.Patterns.aggregation;
public class RemoveEmptyGlobalAggregation
implements Rule
{
private static final Pattern PATTERN =
aggregation()
.with(step().equalTo(AggregationNode.Step.SINGLE))
.matching(node ->
// no aggregate functions
node.getAggregations().isEmpty() &&
node.hasSingleGlobalAggregation());
@Override
public Pattern getPattern()
{
return PATTERN;
}
@Override
public Result apply(AggregationNode node, Captures captures, Context context)
{
// There should be no hash symbol in a global aggregation
checkArgument(node.getHashSymbol().isEmpty(), "Unexpected hash symbol: %s", node.getHashSymbol());
// There should be no output symbols, since there is no information the aggregation could return
checkArgument(node.getOutputSymbols().isEmpty(), "Unexpected output symbols: %s", node.getOutputSymbols());
return Result.ofPlanNode(new ValuesNode(node.getId(), 1));
}
}