/*
* 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.index;
import org.h2.command.query.AllColumnsForPlan;
import org.h2.engine.SessionLocal;
import org.h2.message.DbException;
import org.h2.result.SearchRow;
import org.h2.result.SortOrder;
import org.h2.table.FunctionTable;
import org.h2.table.IndexColumn;
import org.h2.table.TableFilter;
import org.h2.table.VirtualConstructedTable;
/**
* An index for a virtual table that returns a result set. Search in this index
* performs scan over all rows and should be avoided.
*/
public class VirtualConstructedTableIndex extends VirtualTableIndex {
private final VirtualConstructedTable table;
public VirtualConstructedTableIndex(VirtualConstructedTable table, IndexColumn[] columns) {
super(table, null, columns);
this.table = table;
}
@Override
public boolean isFindUsingFullTableScan() {
return true;
}
@Override
public Cursor find(SessionLocal session, SearchRow first, SearchRow last) {
return new VirtualTableCursor(this, first, last, table.getResult(session));
}
@Override
public double getCost(SessionLocal session, int[] masks, TableFilter[] filters, int filter, SortOrder sortOrder,
AllColumnsForPlan allColumnsSet) {
if (masks != null) {
throw DbException.getUnsupportedException("Virtual table");
}
long expectedRows;
if (table.canGetRowCount(session)) {
expectedRows = table.getRowCountApproximation(session);
} else {
expectedRows = database.getSettings().estimatedFunctionTableRows;
}
return expectedRows * 10;
}
@Override
public String getPlanSQL() {
return table instanceof FunctionTable ? "function" : "table scan";
}
@Override
public boolean canScan() {
return false;
}
}