@Override
  protected void doAlteration(Table table, Partition partition) throws HiveException {
    StorageDescriptor sd = getStorageDescriptor(table, partition);
    sd.getSerdeInfo().getParameters().putAll(desc.getProps());
  }
Operation process of setting serde properties.
ql/src/java/org/apache/hadoop/hive/ql/ddl/table/storage/serde/AlterTableSetSerdePropsOperation.java