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Core Calcite APIs and engine.
/*
* 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 org.apache.calcite.schema;
import org.apache.calcite.rel.RelCollation;
import org.apache.calcite.rel.RelDistribution;
import org.apache.calcite.rel.RelDistributionTraitDef;
import org.apache.calcite.rel.RelReferentialConstraint;
import org.apache.calcite.util.ImmutableBitSet;
import com.google.common.collect.ImmutableList;
import java.util.List;
/**
* Utility functions regarding {@link Statistic}.
*/
public class Statistics {
private Statistics() {
}
/** Returns a {@link Statistic} that knows nothing about a table. */
public static final Statistic UNKNOWN =
new Statistic() {
public Double getRowCount() {
return null;
}
public boolean isKey(ImmutableBitSet columns) {
return false;
}
public List getReferentialConstraints() {
return ImmutableList.of();
}
public List getCollations() {
return ImmutableList.of();
}
public RelDistribution getDistribution() {
return RelDistributionTraitDef.INSTANCE.getDefault();
}
};
/** Returns a statistic with a given set of referential constraints. */
public static Statistic of(final List referentialConstraints) {
return of(null, ImmutableList.of(),
referentialConstraints, ImmutableList.of());
}
/** Returns a statistic with a given row count and set of unique keys. */
public static Statistic of(final double rowCount,
final List keys) {
return of(rowCount, keys, ImmutableList.of(),
ImmutableList.of());
}
/** Returns a statistic with a given row count, set of unique keys,
* and collations. */
public static Statistic of(final double rowCount,
final List keys,
final List collations) {
return of(rowCount, keys, ImmutableList.of(), collations);
}
/** Returns a statistic with a given row count, set of unique keys,
* referential constraints, and collations. */
public static Statistic of(final Double rowCount,
final List keys,
final List referentialConstraints,
final List collations) {
return new Statistic() {
public Double getRowCount() {
return rowCount;
}
public boolean isKey(ImmutableBitSet columns) {
for (ImmutableBitSet key : keys) {
if (columns.contains(key)) {
return true;
}
}
return false;
}
public List getReferentialConstraints() {
return referentialConstraints;
}
public List getCollations() {
return collations;
}
public RelDistribution getDistribution() {
return RelDistributionTraitDef.INSTANCE.getDefault();
}
};
}
}
// End Statistics.java
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