protected function findViewNames($schema = '')
    {
        if ($schema === '') {
            $schema = $this->defaultSchema;
        }
        $sql = <<<'SQL'
SELECT c.relname AS table_name
FROM pg_class c
INNER JOIN pg_namespace ns ON ns.oid = c.relnamespace
WHERE ns.nspname = :schemaName AND (c.relkind = 'v' OR c.relkind = 'm')
ORDER BY c.relname
SQL;
        return $this->db->createCommand($sql, [':schemaName' => $schema])->queryColumn();
    }
protected function findViewNames($schema = '')
    {
        if ($schema === '') {
            $schema = $this->defaultSchema;
        }
        $sql = <<<'SQL'
SELECT c.relname AS table_name
FROM pg_class c
INNER JOIN pg_namespace ns ON ns.oid = c.relnamespace
WHERE ns.nspname = :schemaName AND (c.relkind = 'v' OR c.relkind = 'm')
ORDER BY c.relname
SQL;
        return $this->db->createCommand($sql, [':schemaName' => $schema])->queryColumn();
    }
{@inheritdoc]