com.hazelcast.org.apache.calcite.schema.Statistic 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 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 com.hazelcast.org.apache.calcite.schema;
import com.hazelcast.org.apache.calcite.rel.RelCollation;
import com.hazelcast.org.apache.calcite.rel.RelDistribution;
import com.hazelcast.org.apache.calcite.rel.RelReferentialConstraint;
import com.hazelcast.org.apache.calcite.util.ImmutableBitSet;
import java.util.List;
/**
* Statistics about a {@link Table}.
*
* Each of the methods may return {@code null} meaning "not known".
*
* @see Statistics
*/
public interface Statistic {
/** Returns the approximate number of rows in the table. */
Double getRowCount();
/** Returns whether the given set of columns is a unique key, or a superset
* of a unique key, of the table.
*/
boolean isKey(ImmutableBitSet columns);
/** Returns a list of unique keys, or null if no key exist. */
List getKeys();
/** Returns the collection of referential constraints (foreign-keys)
* for this table. */
List getReferentialConstraints();
/** Returns the collections of columns on which this table is sorted. */
List getCollations();
/** Returns the distribution of the data in this table. */
RelDistribution getDistribution();
}