presto-redis/src/main/java/io/prestosql/plugin/redis/RedisMetadata.java/RedisMetadata/listSchemaNames
class RedisMetadata:    @Override
    public List<String> listSchemaNames(ConnectorSession session)
    {
        Set<String> schemas = getDefinedTables().keySet().stream()
                .map(SchemaTableName::getSchemaName)
                .collect(Collectors.toCollection(LinkedHashSet::new));

        return ImmutableList.copyOf(schemas);
    }