/* This file is part of VoltDB.
* Copyright (C) 2008-2017 VoltDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with VoltDB. If not, see <http://www.gnu.org/licenses/>.
*/
package org.voltdb.planner;
/**
* This enum describes the possible ways to use an Index in an
* access path.
*
*/
public enum IndexUseType {
/**
* The index key matches the predicate completely.
* Unique indexes return one or no tuples.
* Non-unique indexes may return many tuples.
*
* All index types should work.
*/
COVERING_UNIQUE_EQUALITY,
/**
* Given a start and stop searchkey,
* Scan from the smallest key > start
* to the largest key < end.
*
* This only works for trees.
*/
INDEX_SCAN,
/**
* If the range of keys to scan is fixed and small,
* try equality searching on all possible keys.
*
* This works for all indexes.
* Not yet supported (needs union executor).
*/
REPEATED_SCAN,
}