| /* |
| |
| Derby - Class org.apache.derby.vti.IFastPath |
| |
| 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.derby.vti; |
| |
| import org.apache.derby.iapi.types.DataValueDescriptor; |
| import org.apache.derby.iapi.error.StandardException; |
| import java.sql.ResultSet; |
| import java.sql.SQLException; |
| |
| /** |
| An internal api for VTIs to allow VTI's written |
| in terms of the datatype system, e.g. returning rows. |
| This allows passing of data from the VTI into the |
| query engine without a conversion through a JDBC ResultSet. |
| */ |
| public interface IFastPath { |
| |
| /** |
| Indicates nextRow() has completed its scan. |
| */ |
| public int SCAN_COMPLETED = -1; |
| /** |
| Indicates nextRow() found a row.. |
| */ |
| public int GOT_ROW = 0; |
| /** |
| Indicates nextRow() has completed its scan but executeQuery must be called to |
| complete the query. |
| */ |
| public int NEED_RS = 1; |
| |
| /** |
| Start a query. |
| Returns true if the VTI will start |
| out as a fast path query and thus rows will be returned |
| by nextRow(). |
| Returns false if the engine must call the VTI's PreparedStatement.executeQuery() |
| method to execute as a regular ResultSet VTI. |
| */ |
| public boolean executeAsFastPath() |
| throws StandardException, SQLException; |
| |
| /** |
| When operating in fast path mode return the next row into the passed in row parameter. |
| Returns GOT_ROW if a valid row is found. |
| Returns SCAN_COMPLETED if the scan is complete. |
| Returns NEED_RS if the rest of the query must be handled as a regular ResultSet VTI by |
| the engine calling the VTI's PreparedStatement.executeQuery() |
| |
| */ |
| public int nextRow(DataValueDescriptor[] row) |
| throws StandardException, SQLException; |
| |
| |
| /** |
| A call from the VTI execution layer back into the supplied VTI. |
| Presents the row just processed as an array of DataValueDescriptors. |
| This only called when the VTI is being executed as a regular ResultSet VTI |
| */ |
| public void currentRow(ResultSet rs, DataValueDescriptor[] row) |
| throws StandardException, SQLException; |
| |
| |
| /** |
| Called once the ResultSet returned by executeQuery() has emptied all of its |
| rows (next() has returned false). |
| */ |
| public void rowsDone() throws StandardException, SQLException; |
| } |