com.hazelcast.org.apache.calcite.materialize.LatticeStatisticProvider Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you under the Apache License, Version 2.0
* (the "License"); you may not use this file except in com.hazelcast.com.liance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.com.hazelcast.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 com.hazelcast.org.apache.calcite.materialize;
import java.util.List;
import java.util.function.Function;
/**
* Estimates row counts for a lattice and its attributes.
*/
public interface LatticeStatisticProvider {
/** Returns an estimate of the number of distinct values in a column
* or list of columns. */
double cardinality(List columns);
/** Creates a {@link LatticeStatisticProvider} for a given
* {@link com.hazelcast.org.apache.calcite.materialize.Lattice}. */
interface Factory extends Function {
}
}