/*
* Copyright 2004-2013 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.lealone.dbobject.index;
import org.lealone.dbobject.table.Column;
import org.lealone.dbobject.table.IndexColumn;
import org.lealone.dbobject.table.TableBase;
import org.lealone.engine.Session;
import org.lealone.message.DbException;
import org.lealone.result.Row;
import org.lealone.result.SearchRow;
import org.lealone.result.SortOrder;
import org.lealone.util.ValueHashMap;
import org.lealone.value.Value;
/**
* An unique index based on an in-memory hash map.
*/
public class HashIndex extends BaseIndex {
/**
* The index of the indexed column.
*/
protected final int indexColumn;
private final TableBase tableData;
private ValueHashMap<Long> rows;
public HashIndex(TableBase table, int id, String indexName, IndexColumn[] columns, IndexType indexType) {
initBaseIndex(table, id, indexName, columns, indexType);
this.indexColumn = columns[0].column.getColumnId();
this.tableData = table;
reset();
}
private void reset() {
rows = ValueHashMap.newInstance();
}
public void truncate(Session session) {
reset();
}
public void add(Session session, Row row) {
Value key = row.getValue(indexColumn);
Object old = rows.get(key);
if (old != null) {
// TODO index duplicate key for hash indexes: is this allowed?
throw getDuplicateKeyException();
}
rows.put(key, row.getKey());
}
public void remove(Session session, Row row) {
rows.remove(row.getValue(indexColumn));
}
public Cursor find(Session session, SearchRow first, SearchRow last) {
if (first == null || last == null) {
// TODO hash index: should additionally check if values are the same
throw DbException.throwInternalError();
}
Row result;
Long pos = rows.get(first.getValue(indexColumn));
if (pos == null) {
result = null;
} else {
result = tableData.getRow(session, pos.intValue());
}
return new SingleRowCursor(result);
}
public long getRowCount(Session session) {
return getRowCountApproximation();
}
public long getRowCountApproximation() {
return rows.size();
}
public long getDiskSpaceUsed() {
return 0;
}
public void close(Session session) {
// nothing to do
}
public void remove(Session session) {
// nothing to do
}
public double getCost(Session session, int[] masks, SortOrder sortOrder) {
for (Column column : columns) {
int index = column.getColumnId();
int mask = masks[index];
if ((mask & IndexCondition.EQUALITY) != IndexCondition.EQUALITY) {
return Long.MAX_VALUE;
}
}
return 2;
}
public void checkRename() {
// ok
}
public boolean needRebuild() {
return true;
}
public boolean canGetFirstOrLast() {
return false;
}
public Cursor findFirstOrLast(Session session, boolean first) {
throw DbException.getUnsupportedException("HASH");
}
public boolean canScan() {
return false;
}
}