diff --git a/src/org/redkale/source/DataDefaultSource.java b/src/org/redkale/source/DataDefaultSource.java
index 631716410..d569aa739 100644
--- a/src/org/redkale/source/DataDefaultSource.java
+++ b/src/org/redkale/source/DataDefaultSource.java
@@ -1360,6 +1360,7 @@ public final class DataDefaultSource implements DataSource, Function<Class, Enti
             if (debug.get() && info.isLoggable(Level.FINEST)) logger.finest(clazz.getSimpleName() + " find sql=" + sql);
             conn.setReadOnly(true);
             final PreparedStatement ps = conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
+            ps.setFetchSize(1);
             final ResultSet set = ps.executeQuery();
             T rs = set.next() ? info.getValue(sels, set) : null;
             set.close();
@@ -1411,6 +1412,7 @@ public final class DataDefaultSource implements DataSource, Function<Class, Enti
             if (debug.get() && info.isLoggable(Level.FINEST)) logger.finest(clazz.getSimpleName() + " find sql=" + sql);
             conn.setReadOnly(true);
             final PreparedStatement ps = conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
+            ps.setFetchSize(1);
             final ResultSet set = ps.executeQuery();
             T rs = set.next() ? info.getValue(sels, set) : null;
             set.close();
@@ -1456,6 +1458,7 @@ public final class DataDefaultSource implements DataSource, Function<Class, Enti
             if (debug.get() && info.isLoggable(Level.FINEST)) logger.finest(clazz.getSimpleName() + " find sql=" + sql);
             conn.setReadOnly(true);
             final PreparedStatement ps = conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
+            ps.setFetchSize(1);
             final ResultSet set = ps.executeQuery();
             Serializable val = defValue;
             if (set.next()) val = (Serializable) set.getObject(1);
@@ -1492,6 +1495,7 @@ public final class DataDefaultSource implements DataSource, Function<Class, Enti
             if (debug.get() && info.isLoggable(Level.FINEST)) logger.finest(clazz.getSimpleName() + " find sql=" + sql);
             conn.setReadOnly(true);
             final PreparedStatement ps = conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
+            ps.setFetchSize(1);
             final ResultSet set = ps.executeQuery();
             Serializable val = defValue;
             if (set.next()) val = (Serializable) set.getObject(1);
@@ -1813,6 +1817,7 @@ public final class DataDefaultSource implements DataSource, Function<Class, Enti
             }
             conn.setReadOnly(true);
             final PreparedStatement ps = conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
+            if (flipper != null && flipper.getLimit() > 0) ps.setFetchSize(flipper.getLimit());
             final ResultSet set = ps.executeQuery();
             if (flipper != null && flipper.getOffset() > 0) set.absolute(flipper.getOffset());
             final int limit = flipper == null || flipper.getLimit() < 1 ? Integer.MAX_VALUE : flipper.getLimit();
diff --git a/src/org/redkale/source/DataSource.java b/src/org/redkale/source/DataSource.java
index 7c2db3b7c..136886f12 100644
--- a/src/org/redkale/source/DataSource.java
+++ b/src/org/redkale/source/DataSource.java
@@ -57,6 +57,17 @@ public interface DataSource {
 
     public <T> int delete(final Class<T> clazz, final FilterNode node);
 
+    /**
+     * 根据过滤条件删除指定行数的数据
+     * Flipper中offset字段将被忽略
+     *
+     * @param <T>     Entity类的泛型
+     * @param clazz   Entity类
+     * @param flipper 翻页对象
+     * @param node    过滤条件
+     *
+     * @return 影响的行数
+     */
     public <T> int delete(final Class<T> clazz, final Flipper flipper, final FilterNode node);
 
     //------------------------update---------------------------
@@ -78,6 +89,18 @@ public interface DataSource {
 
     public <T> int updateColumn(final Class<T> clazz, final FilterNode node, final ColumnValue... values);
 
+    /**
+     * 更新符合条件的记录的指定字段
+     * Flipper中offset字段将被忽略
+     *
+     * @param <T>     Entity类的泛型
+     * @param clazz   Entity类
+     * @param node    过滤条件
+     * @param flipper 翻页对象
+     * @param values  更新字段
+     *
+     * @return 影响的行数
+     */
     public <T> int updateColumn(final Class<T> clazz, final FilterNode node, final Flipper flipper, final ColumnValue... values);
 
     public <T> int updateColumn(final T bean, final String... columns);
@@ -87,8 +110,8 @@ public interface DataSource {
     /**
      * 由 public int updateColumn(final T bean, final String... columns); 代替
      *
-     * @param <T> T
-     * @param bean bean
+     * @param <T>     T
+     * @param bean    bean
      * @param columns columns
      *
      * @return int
@@ -100,9 +123,9 @@ public interface DataSource {
     /**
      * 由 public int updateColumn(final T bean, final FilterNode node, final String... columns); 代替
      *
-     * @param <T> T
-     * @param bean bean
-     * @param node node 
+     * @param <T>     T
+     * @param bean    bean
+     * @param node    node
      * @param columns columns
      *
      * @return int