The key cause by load snapshot failure is that nonclude bytes involved preAlterColumn in these old snapshot data. Due to all data involved tableNode are stored consecutively in the snapshot file. The content of each element during serialization is of variable length, making it impossible to identify the information of preAlteredColumn. So increment a identify to find the position that can read preAlterColumn. (#17004)

Author: zerolbsony

iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/persistence/schema/ConfigMTree.java

@@ -107,6 +107,8 @@ public class ConfigMTree {
   private static final String TABLE_ERROR_MSG =
       "Failed to recover configNode, because there exists data from an older incompatible version, will shutdown soon. Please delete all data, and then restart again.";
 
+  private static final int MARKER_HAVE_PREALTERED_COLUMNS = Integer.MIN_VALUE;
+
   private final Logger logger = LoggerFactory.getLogger(ConfigMTree.class);
   private IConfigMNode root;
   // this store is only used for traverser invoking
@@ -1136,15 +1138,22 @@ private void serializeTableNode(final ConfigTableNode tableNode, final OutputStr
     tableNode.getTable().serialize(outputStream);
     tableNode.getStatus().serialize(outputStream);
     final Set<String> preDeletedColumns = tableNode.getPreDeletedColumns();
-    ReadWriteIOUtils.write(preDeletedColumns.size(), outputStream);
+
+    int preAlteredColumnSize = tableNode.getPreAlteredColumns().size();
+    int preDeletedColumnSize = preDeletedColumns.size();
+    if (preAlteredColumnSize > 0) {
+      ReadWriteIOUtils.write(MARKER_HAVE_PREALTERED_COLUMNS, outputStream);
+      ReadWriteForEncodingUtils.writeVarInt(preAlteredColumnSize, outputStream);
+      for (Entry<String, TSDataType> entry : tableNode.getPreAlteredColumns().entrySet()) {
+        ReadWriteIOUtils.writeVar(entry.getKey(), outputStream);
+        ReadWriteIOUtils.write(entry.getValue(), outputStream);
+      }
+    }
+
+    ReadWriteIOUtils.write(preDeletedColumnSize, outputStream);
     for (final String column : preDeletedColumns) {
       ReadWriteIOUtils.write(column, outputStream);
     }
-    ReadWriteForEncodingUtils.writeVarInt(tableNode.getPreAlteredColumns().size(), outputStream);
-    for (Entry<String, TSDataType> entry : tableNode.getPreAlteredColumns().entrySet()) {
-      ReadWriteIOUtils.writeVar(entry.getKey(), outputStream);
-      ReadWriteIOUtils.write(entry.getValue(), outputStream);
-    }
   }
 
   public void deserialize(final InputStream inputStream) throws IOException {
@@ -1238,16 +1247,20 @@ public static ConfigTableNode deserializeTableMNode(final InputStream inputStrea
     tableNode.setTable(TsTable.deserialize(inputStream));
     tableNode.setStatus(TableNodeStatus.deserialize(inputStream));
     int size = ReadWriteIOUtils.readInt(inputStream);
+    if (size == MARKER_HAVE_PREALTERED_COLUMNS) {
+      size = ReadWriteForEncodingUtils.readVarInt(inputStream);
+      for (int i = 0; i < size; i++) {
+        tableNode.addPreAlteredColumn(
+            ReadWriteIOUtils.readVarIntString(inputStream),
+            ReadWriteIOUtils.readDataType(inputStream));
+      }
+      size = ReadWriteIOUtils.readInt(inputStream);
+    }
+
     for (int i = 0; i < size; ++i) {
       tableNode.addPreDeletedColumn(ReadWriteIOUtils.readString(inputStream));
     }
 
-    size = ReadWriteForEncodingUtils.readVarInt(inputStream);
-    for (int i = 0; i < size; i++) {
-      tableNode.addPreAlteredColumn(
-          ReadWriteIOUtils.readVarIntString(inputStream),
-          ReadWriteIOUtils.readDataType(inputStream));
-    }
     return tableNode;
   }