Add an instance of validation. (#707)

* Add an instance of validation.

* Add a comment.

Author: zerolbsony

java/tsfile/src/main/java/org/apache/tsfile/read/common/block/column/TsBlockSerde.java

@@ -103,7 +103,10 @@ public ByteBuffer serialize(TsBlock tsBlock) throws IOException {
 
     // Value column data types.
     for (int i = 0; i < tsBlock.getValueColumnCount(); i++) {
-      if (tsBlock.getColumn(i).getDataType() == TSDataType.DATE) {
+      // To be compatible with the Python client, because it does not support data type values other
+      // than 0-5, the value of DATE is 9.
+      if ((tsBlock.getColumn(i) instanceof IntColumn)
+          && tsBlock.getColumn(i).getDataType() == TSDataType.DATE) {
         ((IntColumn) tsBlock.getColumn(i)).modifyDataType(TSDataType.INT32);
       }
       tsBlock.getColumn(i).getDataType().serializeTo(dataOutputStream);