public byte[] getSdHash() {
      return sdHash;
    }
this flag is used to validate/invalidate cached constraints snapshot.
All table constraints are update successfully either via updater thread or
while create_table_with_constraint api then it is set to true else
false and redirect all the call to raw metastore.
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/cache/SharedCache.java