@Override
  public Catalog getCatalog(String catalogName) throws NoSuchObjectException, MetaException {
    LOG.debug("Fetching catalog {}", catalogName);
    MCatalog mCat = getMCatalog(catalogName);
    if (mCat == null) {
      throw new NoSuchObjectException("No catalog " + catalogName);
    }
    return mCatToCat(mCat);
  }
Rolls back the current transaction if it is active
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/ObjectStore.java