Adjusted Fix for Issue 56 - Using findIterate with MySQL streams the

entire result set at once.  This makes the fix specific to the
DatabasePlatform and findIterate() or findVisit().

src/main/java/com/avaje/ebean/config/dbplatform/DatabasePlatform.java

@@ -63,6 +63,12 @@ public class DatabasePlatform {
 
   protected boolean selectCountWithAlias;
 
+  /**
+   * If set then use the FORWARD ONLY hint when creating ResultSets for
+   * findIterate() and findVisit().
+   */
+  protected boolean forwardOnlyHintOnFindIterate;
+  
   /**
    * Instantiates a new database platform.
    */
@@ -199,6 +205,24 @@ public class DatabasePlatform {
     return idInExpandedForm;
   }
 
+  /**
+   * Return true if the ResultSet TYPE_FORWARD_ONLY Hint should be used on
+   * findIterate() and findVisit() PreparedStatements.
+   * <p>
+   * This specifically is required for MySql when processing large results.
+   * </p>
+   */
+  public boolean isForwardOnlyHintOnFindIterate() {
+    return forwardOnlyHintOnFindIterate;
+  }
+
+  /**
+   * Set to true if the ResultSet TYPE_FORWARD_ONLY Hint should be used by default on findIterate PreparedStatements.
+   */
+  public void setForwardOnlyHintOnFindIterate(boolean forwardOnlyHintOnFindIterate) {
+    this.forwardOnlyHintOnFindIterate = forwardOnlyHintOnFindIterate;
+  }
+
   /**
    * Return the DB identity/sequence features for this platform.
    * 

src/main/java/com/avaje/ebean/config/dbplatform/MySqlPlatform.java

@@ -31,6 +31,7 @@ public class MySqlPlatform extends DatabasePlatform {
     this.openQuote = "`";
     this.closeQuote = "`";
 
+    this.forwardOnlyHintOnFindIterate = true;
     this.booleanDbType = Types.BIT;
 
     dbTypeMap.put(Types.BIT, new DbType("tinyint(1) default 0"));

src/main/java/com/avaje/ebeaninternal/server/query/CQuery.java

@@ -346,8 +346,8 @@ public class CQuery<T> implements DbReadContext, CancelableQuery {
   /**
    * Prepare bind and execute query with Forward only hints.
    */
-  public boolean prepareBindExecuteQueryForwardOnly() throws SQLException {
-    return prepareBindExecuteQueryWithOption(true);
+  public boolean prepareBindExecuteQueryForwardOnly(boolean dbPlatformForwardOnlyHint) throws SQLException {
+    return prepareBindExecuteQueryWithOption(dbPlatformForwardOnlyHint);
   }
 
   /**
@@ -357,7 +357,7 @@ public class CQuery<T> implements DbReadContext, CancelableQuery {
     return prepareBindExecuteQueryWithOption(false);
   }
 
-  private boolean prepareBindExecuteQueryWithOption(boolean forward) throws SQLException {
+  private boolean prepareBindExecuteQueryWithOption(boolean forwardOnlyHint) throws SQLException {
 
     synchronized (this) {
       if (cancelled || query.isCancelled()) {
@@ -371,8 +371,9 @@ public class CQuery<T> implements DbReadContext, CancelableQuery {
       // prepare
       SpiTransaction t = request.getTransaction();
       Connection conn = t.getInternalConnection();
-      if (forward) {
-        // Hints required for mysql for large resultset processing (Issue 56)
+            
+      if (forwardOnlyHint) {
+        // Use forward only hints for large resultset processing (Issue 56, MySql specific)
         pstmt = conn.prepareStatement(sql, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
       } else {
         pstmt = conn.prepareStatement(sql);        

src/main/java/com/avaje/ebeaninternal/server/query/CQueryEngine.java

@@ -25,6 +25,8 @@ public class CQueryEngine {
 
   private static final Logger logger = LoggerFactory.getLogger(CQueryEngine.class);
 
+  private final DatabasePlatform dbPlatform;
+  
   private final CQueryBuilder queryBuilder;
 
   private final BackgroundExecutor backgroundExecutor;
@@ -33,6 +35,7 @@ public class CQueryEngine {
 
   public CQueryEngine(DatabasePlatform dbPlatform, Binder binder, BackgroundExecutor backgroundExecutor) {
 
+    this.dbPlatform = dbPlatform;
     this.backgroundExecutor = backgroundExecutor;
     this.queryBuilder = new CQueryBuilder(backgroundExecutor, dbPlatform, binder);
   }
@@ -122,7 +125,7 @@ public class CQueryEngine {
 
     try {
 
-      if (!cquery.prepareBindExecuteQueryForwardOnly()) {
+      if (!cquery.prepareBindExecuteQueryForwardOnly(dbPlatform.isForwardOnlyHintOnFindIterate())) {
         // query has been cancelled already
         logger.trace("Future fetch already cancelled");
         return null;