/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.table;
import java.util.LinkedHashSet;
import java.util.Set;
import org.h2.index.Index;
/**
* Contains the hints for which index to use for a specific table. Currently
* allows a list of "use indexes" to be specified.
* <p>
* Use the factory method IndexHints.createUseIndexHints(listOfIndexes) to limit
* the query planner to only use specific indexes when determining which index
* to use for a table
**/
public final class IndexHints {
private final LinkedHashSet<String> allowedIndexes;
private IndexHints(LinkedHashSet<String> allowedIndexes) {
this.allowedIndexes = allowedIndexes;
}
/**
* Create an index hint object.
*
* @param allowedIndexes the set of allowed indexes
* @return the hint object
*/
public static IndexHints createUseIndexHints(LinkedHashSet<String> allowedIndexes) {
return new IndexHints(allowedIndexes);
}
public Set<String> getAllowedIndexes() {
return allowedIndexes;
}
@Override
public String toString() {
return "IndexHints{allowedIndexes=" + allowedIndexes + '}';
}
/**
* Allow an index to be used.
*
* @param index the index
* @return whether it was already allowed
*/
public boolean allowIndex(Index index) {
return allowedIndexes.contains(index.getName());
}
}