Optimise the case where we are accessing the ResultSet column values by name.

Patch by Carl Hasselskog (carl@degoo.com)

h2/src/main/org/h2/jdbc/JdbcPreparedStatement.java

@@ -22,6 +22,8 @@ import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.ArrayList;
 import java.util.Calendar;
+import java.util.HashMap;
+
 import org.h2.command.CommandInterface;
 import org.h2.constant.ErrorCode;
 import org.h2.expression.ParameterInterface;
@@ -62,6 +64,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
     protected CommandInterface command;
     private final String sqlStatement;
     private ArrayList<Value[]> batchParameters;
+    private HashMap<String, Integer> cachedColumnLabelMap = null;
 
     JdbcPreparedStatement(JdbcConnection conn, String sql, int id, int resultSetType,
                 int resultSetConcurrency, boolean closeWithResultSet) {
@@ -71,6 +74,14 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
         command = conn.prepareCommand(sql, fetchSize);
     }
 
+    /**
+     * Looking up the column index can sometimes show up on the performance profile,
+     * so cache the map.
+     */
+    void setCachedColumnLabelMap( HashMap<String, Integer> cachedColumnLabelMap) {
+    	this.cachedColumnLabelMap = cachedColumnLabelMap;
+    }
+    
     /**
      * Executes a query (select statement) and returns the result set. If
      * another result set exists for this statement, this will be closed (even
@@ -97,7 +108,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
                 } finally {
                     setExecutingStatement(null);
                 }
-                resultSet = new JdbcResultSet(conn, this, result, id, closedByResultSet, scrollable, updatable);
+                resultSet = new JdbcResultSet(conn, this, result, id, closedByResultSet, scrollable, updatable, cachedColumnLabelMap);               
             }
             return resultSet;
         } catch (Exception e) {

h2/src/main/org/h2/jdbc/JdbcResultSet.java

@@ -91,6 +91,7 @@ public class JdbcResultSet extends TraceObject implements ResultSet {
     private Value[] updateRow;
     private HashMap<String, Integer> columnLabelMap;
     private HashMap<Integer, Value[]> patchedRows;
+    private JdbcPreparedStatement preparedStatement = null;
 
     JdbcResultSet(JdbcConnection conn, JdbcStatement stat, ResultInterface result, int id,
                 boolean closeStatement, boolean scrollable, boolean updatable) {
@@ -103,6 +104,16 @@ public class JdbcResultSet extends TraceObject implements ResultSet {
         this.scrollable = scrollable;
         this.updatable = updatable;
     }
+    
+    /**
+     * Overload used to explicitly set the column-mapping.
+     */
+    JdbcResultSet(JdbcConnection conn, JdbcPreparedStatement preparedStatement, ResultInterface result, int id,
+            boolean closeStatement, boolean scrollable, boolean updatable, HashMap<String, Integer> columnLabelMap) {
+    	  this(conn, preparedStatement, result, id, closeStatement, scrollable, updatable);
+    	  this.columnLabelMap = columnLabelMap;
+    	  this.preparedStatement = preparedStatement;
+    }
 
     /**
      * Moves the cursor to the next row of the result set.
@@ -2876,6 +2887,9 @@ public class JdbcResultSet extends TraceObject implements ResultSet {
                 }
                 // assign at the end so concurrent access is supported
                 columnLabelMap = map;
+                if (preparedStatement != null) {
+                    preparedStatement.setCachedColumnLabelMap(columnLabelMap);
+                }
             }
             Integer index = columnLabelMap.get(StringUtils.toUpperEnglish(columnLabel));
             if (index == null) {