diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/IDataType.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/IDataType.java
index b8407e3a..843395d3 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/IDataType.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/IDataType.java
@@ -21,18 +21,27 @@
 import java.io.IOException;
 import java.sql.SQLException;
 
-// It would be nice if we introduce a Generic Type, `IDataType<T>`, then we can avoid using `Object` and type cast.
-// Unfortunately Java not support unsigned number, UInt8(u_byte) must be represented by Int16(short), which will
-// break the Generic Type constriction and cause compile failed.
-public interface IDataType {
+/**
+ * IDataType is responsible for:
+ * 1. represent data type attributions
+ * 2. serialize and deserialize
+ * 3. parse from sql text
+ * 4. cast between inner type and other types
+ * 5. format to string
+ * @param <T> inner data type, 1:1 map to ClickHouse data type
+ */
+public interface IDataType<T> {
 
+    // 1. represent data type attributions
     String name();
 
-    int sqlTypeId();
+    default String[] getAliases() {
+        return new String[0];
+    }
 
-    Object defaultValue();
+    int sqlTypeId();
 
-    Class javaTypeClass();
+    Class<T> javaTypeClass();
 
     boolean nullable();
 
@@ -40,21 +49,35 @@ public interface IDataType {
 
     int getScale();
 
-    Object deserializeTextQuoted(SQLLexer lexer) throws SQLException;
+    T defaultValue();
 
-    Object deserializeBinary(BinaryDeserializer deserializer) throws SQLException, IOException;
+    // 2. serialize and deserialize
+    void serializeBinary(T data, BinarySerializer serializer) throws SQLException, IOException;
 
-    void serializeBinary(Object data, BinarySerializer serializer) throws SQLException, IOException;
-
-    default void serializeBinaryBulk(Object[] data, BinarySerializer serializer) throws SQLException, IOException {
-        for (Object d : data) {
-            serializeBinary(d, serializer);
+    default void serializeBinaryBulk(T[] values, BinarySerializer serializer) throws SQLException, IOException {
+        for (T value : values) {
+            serializeBinary(value, serializer);
         }
     }
 
-    Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException;
+    T deserializeBinary(BinaryDeserializer deserializer) throws SQLException, IOException;
 
-    default String[] getAliases() {
-        return new String[0];
+    T[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException;
+
+    // 3. parse from sql text
+    T deserializeTextQuoted(SQLLexer lexer) throws SQLException;
+
+    // 4. cast between inner type and other types
+    default <O> T castFrom(O other) {
+        return javaTypeClass().cast(other);
+    }
+
+    default <O> O castTo(T inner, Class<O> castToClazz) {
+        return castToClazz.cast(inner);
+    }
+
+    // 5. format to string
+    default <O> String format(O value) {
+        return castTo(castFrom(value), String.class);
     }
 }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeDate.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeDate.java
index a920444c..a8039b51 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeDate.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeDate.java
@@ -82,9 +82,9 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws IOExcept
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws IOException {
-        Date[] data = new Date[rows];
-        for (int row = 0; row < rows; row++) {
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws IOException {
+        Date[] data = new Date[rowCnt];
+        for (int row = 0; row < rowCnt; row++) {
             short daysSinceEpoch = deserializer.readShort();
             data[row] = Date.valueOf(LocalDate.ofEpochDay(daysSinceEpoch));
         }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeFloat32.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeFloat32.java
index dfaf374d..35ae002f 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeFloat32.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeFloat32.java
@@ -73,10 +73,10 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws IOExcept
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws IOException {
-        Float[] data = new Float[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = deserializer.readFloat();
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws IOException {
+        Float[] data = new Float[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = deserializer.readFloat();
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeFloat64.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeFloat64.java
index 2de20ff5..931f52c8 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeFloat64.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeFloat64.java
@@ -73,10 +73,10 @@ public Double deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Double[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws IOException {
-        Double[] data = new Double[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = deserializer.readDouble();
+    public Double[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws IOException {
+        Double[] data = new Double[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = deserializer.readDouble();
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeIPv4.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeIPv4.java
index a71bcc05..a0070ea5 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeIPv4.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeIPv4.java
@@ -73,10 +73,10 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        Object[] data = new Object[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = this.deserializeBinary(deserializer);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        Object[] data = new Object[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = this.deserializeBinary(deserializer);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt16.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt16.java
index 7e0eafe2..36aec2c8 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt16.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt16.java
@@ -84,10 +84,10 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        Object[] data = new Object[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = this.deserializeBinary(deserializer);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        Object[] data = new Object[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = this.deserializeBinary(deserializer);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt32.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt32.java
index fd4e401c..1c437e92 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt32.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt32.java
@@ -84,11 +84,11 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer)
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer)
             throws SQLException, IOException {
-        Object[] data = new Object[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = this.deserializeBinary(deserializer);
+        Object[] data = new Object[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = this.deserializeBinary(deserializer);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt64.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt64.java
index 42a4edbe..2b1d5990 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt64.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt64.java
@@ -96,11 +96,11 @@ public BigInteger parseBigIntegerPositive(String num, int bitlen) {
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer)
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer)
             throws SQLException, IOException {
-        Object[] data = new Object[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = this.deserializeBinary(deserializer);
+        Object[] data = new Object[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = this.deserializeBinary(deserializer);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt8.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt8.java
index 6f786ff0..2f620003 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt8.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeInt8.java
@@ -84,10 +84,10 @@ public Number deserializeBinary(BinaryDeserializer deserializer) throws IOExcept
     }
 
     @Override
-    public Number[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws IOException {
-        Number[] data = new Number[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = deserializeBinary(deserializer);
+    public Number[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws IOException {
+        Number[] data = new Number[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = deserializeBinary(deserializer);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeUUID.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeUUID.java
index 8ffb24bc..0416dd9c 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeUUID.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/DataTypeUUID.java
@@ -79,10 +79,10 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        String[] data = new String[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = (String) deserializeBinary(deserializer);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        String[] data = new String[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = (String) deserializeBinary(deserializer);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeArray.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeArray.java
index 2584f84b..efca8c18 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeArray.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeArray.java
@@ -117,11 +117,10 @@ public void serializeBinary(Object data, BinarySerializer serializer) throws SQL
         }
     }
 
-
     @Override
-    public void serializeBinaryBulk(Object[] data, BinarySerializer serializer) throws SQLException, IOException {
-        offsetIDataType.serializeBinary(data.length, serializer);
-        getElemDataType().serializeBinaryBulk(data, serializer);
+    public void serializeBinaryBulk(Object[] values, BinarySerializer serializer) throws SQLException, IOException {
+        offsetIDataType.serializeBinary(values.length, serializer);
+        getElemDataType().serializeBinaryBulk(values, serializer);
     }
 
     @Override
@@ -131,17 +130,17 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws IOException, SQLException {
-        ClickHouseArray[] data = new ClickHouseArray[rows];
-        if (rows == 0) {
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws IOException, SQLException {
+        ClickHouseArray[] data = new ClickHouseArray[rowCnt];
+        if (rowCnt == 0) {
             return data;
         }
 
-        Object[] offsets = offsetIDataType.deserializeBinaryBulk(rows, deserializer);
+        Object[] offsets = offsetIDataType.deserializeBinaryBulk(rowCnt, deserializer);
         ClickHouseArray res = new ClickHouseArray(elemDataType,
-                elemDataType.deserializeBinaryBulk(((BigInteger) offsets[rows - 1]).intValue(), deserializer));
+                elemDataType.deserializeBinaryBulk(((BigInteger) offsets[rowCnt - 1]).intValue(), deserializer));
 
-        for (int row = 0, lastOffset = 0; row < rows; row++) {
+        for (int row = 0, lastOffset = 0; row < rowCnt; row++) {
             BigInteger offset = (BigInteger) offsets[row];
             data[row] = res.slice(lastOffset, offset.intValue() - lastOffset);
             lastOffset = offset.intValue();
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDateTime.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDateTime.java
index 136dfdca..0b29c42c 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDateTime.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDateTime.java
@@ -119,10 +119,10 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        Timestamp[] data = new Timestamp[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = new Timestamp(deserializer.readInt() * 1000L);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        Timestamp[] data = new Timestamp[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = new Timestamp(deserializer.readInt() * 1000L);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDateTime64.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDateTime64.java
index b86125a7..fdb303cd 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDateTime64.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDateTime64.java
@@ -156,10 +156,10 @@ public void serializeBinary(Object data, BinarySerializer serializer) throws IOE
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws IOException {
-        Timestamp[] data = new Timestamp[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = (Timestamp) deserializeBinary(deserializer);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws IOException {
+        Timestamp[] data = new Timestamp[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = (Timestamp) deserializeBinary(deserializer);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDecimal.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDecimal.java
index 37703638..c57b9d3d 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDecimal.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeDecimal.java
@@ -204,10 +204,10 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        BigDecimal[] data = new BigDecimal[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = (BigDecimal) this.deserializeBinary(deserializer);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        BigDecimal[] data = new BigDecimal[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = (BigDecimal) this.deserializeBinary(deserializer);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeEnum16.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeEnum16.java
index 0cc5aa40..e1175a14 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeEnum16.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeEnum16.java
@@ -139,10 +139,10 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        String[] data = new String[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = (String) deserializeBinary(deserializer);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        String[] data = new String[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = (String) deserializeBinary(deserializer);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeEnum8.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeEnum8.java
index fb53f372..044f0d8a 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeEnum8.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeEnum8.java
@@ -139,10 +139,10 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        String[] data = new String[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = (String) deserializeBinary(deserializer);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        String[] data = new String[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = (String) deserializeBinary(deserializer);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeFixedString.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeFixedString.java
index 719e4170..adf6770d 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeFixedString.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeFixedString.java
@@ -123,10 +123,10 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        String[] data = new String[rows];
-        for (int row = 0; row < rows; row++) {
-            data[row] = new String(deserializer.readBytes(n), charset);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        String[] data = new String[rowCnt];
+        for (int i = 0; i < rowCnt; i++) {
+            data[i] = new String(deserializer.readBytes(n), charset);
         }
         return data;
     }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeNullable.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeNullable.java
index 2910a2d7..1aaea030 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeNullable.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeNullable.java
@@ -114,21 +114,21 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public void serializeBinaryBulk(Object[] data, BinarySerializer serializer) throws SQLException, IOException {
-        Short[] isNull = new Short[data.length];
-        for (int i = 0; i < data.length; i++) {
-            isNull[i] = (data[i] == null ? IS_NULL : NON_NULL);
-            data[i] = data[i] == null ? nestedDataType.defaultValue() : data[i];
+    public void serializeBinaryBulk(Object[] values, BinarySerializer serializer) throws SQLException, IOException {
+        Short[] isNull = new Short[values.length];
+        for (int i = 0; i < values.length; i++) {
+            isNull[i] = (values[i] == null ? IS_NULL : NON_NULL);
+            values[i] = values[i] == null ? nestedDataType.defaultValue() : values[i];
         }
         nullMapDataType.serializeBinaryBulk(isNull, serializer);
-        nestedDataType.serializeBinaryBulk(data, serializer);
+        nestedDataType.serializeBinaryBulk(values, serializer);
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        Object[] nullMap = nullMapDataType.deserializeBinaryBulk(rows, deserializer);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        Object[] nullMap = nullMapDataType.deserializeBinaryBulk(rowCnt, deserializer);
 
-        Object[] data = nestedDataType.deserializeBinaryBulk(rows, deserializer);
+        Object[] data = nestedDataType.deserializeBinaryBulk(rowCnt, deserializer);
         for (int i = 0; i < nullMap.length; i++) {
             if (IS_NULL.equals(nullMap[i])) {
                 data[i] = null;
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeString.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeString.java
index 63f051ec..bfedc413 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeString.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeString.java
@@ -94,9 +94,9 @@ public String deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        String[] data = new String[rows];
-        for (int row = 0; row < rows; row++) {
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        String[] data = new String[rowCnt];
+        for (int row = 0; row < rowCnt; row++) {
             byte[] bs = deserializer.readBytesBinary();
             data[row] = new String(bs, charset);
         }
diff --git a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeTuple.java b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeTuple.java
index a86c3f28..acc7abc0 100644
--- a/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeTuple.java
+++ b/clickhouse-native-jdbc/src/main/java/com/github/housepower/jdbc/data/type/complex/DataTypeTuple.java
@@ -119,22 +119,22 @@ public Object deserializeBinary(BinaryDeserializer deserializer) throws SQLExcep
     }
 
     @Override
-    public void serializeBinaryBulk(Object[] data, BinarySerializer serializer) throws SQLException, IOException {
+    public void serializeBinaryBulk(Object[] values, BinarySerializer serializer) throws SQLException, IOException {
         for (int i = 0; i < nestedTypes.length; i++) {
-            Object[] elemsData = new Object[data.length];
-            for (int row = 0; row < data.length; row++) {
-                elemsData[row] = ((Struct) data[row]).getAttributes()[i];
+            Object[] elemsData = new Object[values.length];
+            for (int row = 0; row < values.length; row++) {
+                elemsData[row] = ((Struct) values[row]).getAttributes()[i];
             }
             nestedTypes[i].serializeBinaryBulk(elemsData, serializer);
         }
     }
 
     @Override
-    public Object[] deserializeBinaryBulk(int rows, BinaryDeserializer deserializer) throws SQLException, IOException {
-        Object[][] rowsWithElems = getRowsWithElems(rows, deserializer);
+    public Object[] deserializeBinaryBulk(int rowCnt, BinaryDeserializer deserializer) throws SQLException, IOException {
+        Object[][] rowsWithElems = getRowsWithElems(rowCnt, deserializer);
 
-        Struct[] rowsData = new Struct[rows];
-        for (int row = 0; row < rows; row++) {
+        Struct[] rowsData = new Struct[rowCnt];
+        for (int row = 0; row < rowCnt; row++) {
             Object[] elemsData = new Object[nestedTypes.length];
 
             for (int elemIndex = 0; elemIndex < nestedTypes.length; elemIndex++) {