MONDRIAN: Fix for MONDRIAN-528 - MySQL incorrectly identified as usin…

…g Infobright Dialect.

Included notes in Javadoc for implementing Dialects

[git-p4: depot-paths = "//open/mondrian/": change = 12593]

src/main/mondrian/spi/impl/InfobrightDialect.java

@@ -23,9 +23,7 @@ public class InfobrightDialect extends MySqlDialect {
     public static final JdbcDialectFactory FACTORY =
         new JdbcDialectFactory(
             InfobrightDialect.class,
-            // While we're choosing dialects, this still looks like a MySQL
-            // connection.
-            DatabaseProduct.MYSQL);
+            DatabaseProduct.INFOBRIGHT);
 
     /**
      * Creates an InfobrightDialect.
@@ -36,10 +34,6 @@ public InfobrightDialect(Connection connection) throws SQLException {
         super(connection);
     }
 
-    public DatabaseProduct getDatabaseProduct() {
-        return DatabaseProduct.INFOBRIGHT;
-    }
-
     public boolean allowsCompoundCountDistinct() {
         return false;
     }

src/main/mondrian/spi/impl/JdbcDialectFactory.java

@@ -110,6 +110,17 @@ public static Dialect createDialectHelper(
         }
     }
 
+    /**
+     * Generate a valid dialect for the connection, or null if
+     * the connection is not for the given DatabaseProduct.
+     *
+     * Instantiates a Dialect and tests it. Dialects may run queries and other
+     * operations to determine the database product behind the connection.
+     *
+     * @param dataSource JDBC data source, if null need connection
+     * @param connection JDBC connection, if null nee data source
+     * @return Dialect, or null if factory cannot create suitable dialect
+     */
     public Dialect createDialect(DataSource dataSource, Connection connection) {
         // If connection is null, create a temporary connection and
         // recursively call this method.
@@ -118,40 +129,26 @@ public Dialect createDialect(DataSource dataSource, Connection connection) {
         }
 
         assert connection != null;
-        if (acceptsConnection(connection)) {
-            try {
-                return constructor.newInstance(connection);
-            } catch (InstantiationException e) {
-                throw Util.newError(
-                    e, "Error while instantiating dialect");
-            } catch (IllegalAccessException e) {
-                throw Util.newError(
-                    e, "Error while instantiating dialect");
-            } catch (InvocationTargetException e) {
-                throw Util.newError(
-                    e, "Error while instantiating dialect");
-            }
-        }
-        return null;
-    }
 
-    /**
-     * Returns whether this dialect is suitable for the given connection.
-     *
-     * @param connection Connection
-     * @return Whether suitable
-     */
-    private boolean acceptsConnection(Connection connection) {
+        Dialect newDialect = null;
         try {
-            final DatabaseMetaData metaData = connection.getMetaData();
-            final String productName = metaData.getDatabaseProductName();
-            final String productVersion = metaData.getDatabaseProductVersion();
-            final Dialect.DatabaseProduct product =
-                JdbcDialectImpl.getProduct(productName, productVersion);
-            return product == this.databaseProduct;
-        } catch (SQLException e) {
+            newDialect = constructor.newInstance(connection);
+        } catch (InstantiationException e) {
+            throw Util.newError(
+                e, "Error while instantiating dialect");
+        } catch (IllegalAccessException e) {
             throw Util.newError(
                 e, "Error while instantiating dialect");
+        } catch (InvocationTargetException e) {
+            throw Util.newError(
+                e, "Error while instantiating dialect");
+        }
+
+        if (newDialect == null ||
+                newDialect.getDatabaseProduct() != this.databaseProduct) {
+            return null;
+        } else {
+            return newDialect;
         }
     }
 }

src/main/mondrian/spi/impl/JdbcDialectImpl.java

@@ -28,6 +28,16 @@
  * specific dialect. JdbcDialectImpl reads properties from the JDBC driver's
  * metadata, so can deduce some of the dialect's behavior.</p>
  *
+ * <p>Implementing a Dialect will include changing the getProduct method in this
+ * class and changing the list of Dialects in the {@link Dialect} interface. If
+ * dialect specific SQL is required in the schema, the Mondrian schema will need
+ * to be updated.</p>
+ *
+ * <p>Note that subclasses of JdbcDialectImpl will be instantiated with JDBC
+ * connections that are not of the actual database product the subclass
+ * supports. This is done as part of determining the correct dialect for the
+ * connection.</p>
+ *
  * @author jhyde
  * @version $Id$
  * @since Oct 10, 2008

src/main/mondrian/spi/impl/MySqlDialect.java

@@ -11,7 +11,6 @@
 import mondrian.olap.Util;
 import mondrian.spi.Dialect;
 
-import javax.sql.DataSource;
 import java.util.List;
 import java.sql.*;
 
@@ -27,27 +26,7 @@ public class MySqlDialect extends JdbcDialectImpl {
     public static final JdbcDialectFactory FACTORY =
         new JdbcDialectFactory(
             MySqlDialect.class,
-            DatabaseProduct.MYSQL)
-        {
-            @Override
-            public Dialect createDialect(
-                DataSource dataSource,
-                Connection connection)
-            {
-                final Dialect dialect =
-                    super.createDialect(
-                        dataSource, connection);
-                // Infobright looks a lot like MySQL. If this is an Infobright
-                // connection, yield to the Infobright dialect.
-                if (dialect != null &&
-                    dialect instanceof MySqlDialect &&
-                    ((MySqlDialect) dialect).getDatabaseProduct() ==
-                    DatabaseProduct.INFOBRIGHT) {
-                    return null;
-                }
-                return dialect;
-            }
-        };
+            DatabaseProduct.MYSQL);
 
     /**
      * Creates a MySqlDialect.
@@ -73,8 +52,16 @@ private static boolean isInfobright(
     {
         Statement statement = null;
         try {
+            String productName =
+                databaseMetaData.getDatabaseProductName();
             String productVersion =
                 databaseMetaData.getDatabaseProductVersion();
+
+            if (JdbcDialectImpl.getProduct(productName, productVersion) !=
+                    DatabaseProduct.MYSQL) {
+                return false;
+            }
+
             if (productVersion.compareTo("5.1") >= 0) {
                 statement = databaseMetaData.getConnection().createStatement();
                 final ResultSet resultSet =