presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/SemiTransactionalHiveMetastore.java/SemiTransactionalHiveMetastore/dropDatabase
class SemiTransactionalHiveMetastore:    public synchronized void dropDatabase(HiveIdentity identity, String schemaName)
    {
        setExclusive((delegate, hdfsEnvironment) -> delegate.dropDatabase(identity, schemaName));
    }