Implemented PostgreSQL version as a cached property.

from django.db.backends.postgresql_psycopg2.version import get_version

from django.db.backends.postgresql_psycopg2.introspection import DatabaseIntrospection

from django.utils.encoding import force_str

from django.utils.functional import cached_property

from django.utils.safestring import SafeText, SafeBytes

from django.utils import six

from django.utils.timezone import utc

        self.creation = DatabaseCreation(self)

        self.introspection = DatabaseIntrospection(self)

        self.validation = BaseDatabaseValidation(self)

        self._pg_version = None

    def check_constraints(self, table_names=None):

        """

            )

            raise

    def _get_pg_version(self):

        if self._pg_version is None:

            self._pg_version = get_version(self.connection)

        return self._pg_version

    pg_version = property(_get_pg_version)

    @cached_property

    def pg_version(self):

        return get_version(self.connection)

    def get_connection_params(self):

        settings_dict = self.settings_dict

                self.connection.cursor().execute(

                        self.ops.set_time_zone_sql(), [tz])

        self.connection.set_isolation_level(self.isolation_level)

        self._get_pg_version()

    def create_cursor(self):

        cursor = self.connection.cursor()