@Override
  public void close() throws IOException {
    this.transactionExecutors.values().forEach(TransactionExecutor::close);
  }
List named-blobs query, given a prefix.
This query uses a subquery to get the max version of a given blob name.
1. The subquery returns the max version whose blob_state is ready, even if it's deleted.
2. The outer query select goes through all the (blob_name, version) combination and only returns the one when
   version is the max version from the subquery and not deleted.
This list sql statement uses subquery instead of CTE and inner join so it should be more efficient.
ambry-named-mysql/src/main/java/com/github/ambry/named/MySqlNamedBlobDb.java