This class implements a `DBAPI-compliant interface`__. It is what you want
to use if you write a "classic", blocking program (eventually using
threads or Eventlet/gevent for concurrency). If your program uses `asyncio`
you might want to use `AsyncConnection` instead.

.. __: https://www.python.org/dev/peps/pep-0249/#connection-objects

Connections behave as context managers: on block exit, the current
transaction will be committed (or rolled back, in case of exception) and
the connection will be closed.

.. automethod:: connect

    :param conninfo: The `connection string`__ (a ``postgresql://`` url or
        a list of ``key=value`` pairs) to specify where and how to connect.
    :param kwargs: Further parameters specifying the connection string.
        They override the ones specified in `!conninfo`.
    :param autocommit: If `!True` don't start transactions automatically.
        See :ref:`transactions` for details.
    :param row_factory: The row factory specifying what type of records
        to create fetching data (default: `~psycopg.rows.tuple_row()`). See
        :ref:`row-factories` for details.
    :param cursor_factory: Initial value for the `cursor_factory` attribute
        of the connection (new in Psycopg 3.1).
    :param prepare_threshold: Initial value for the `prepare_threshold`
        attribute of the connection (new in Psycopg 3.1).

    More specialized use:

    :param context: A context to copy the initial adapters configuration
        from. It might be an `~psycopg.adapt.AdaptersMap` with customized
        loaders and dumpers, used as a template to create several connections.
        See :ref:`adaptation` for further details.

    .. __: https://www.postgresql.org/docs/current/libpq-connect.html
        #LIBPQ-CONNSTRING

    This method is also aliased as `psycopg.connect()`.

    .. seealso::

        - the list of `the accepted connection parameters`__
        - the `environment variables`__ affecting connection

        .. __: https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-PARAMKEYWORDS
        .. __: https://www.postgresql.org/docs/current/libpq-envars.html

    .. versionchanged:: 3.1
        added `!prepare_threshold` and `!cursor_factory` parameters.

.. attribute:: adapters
    :type: ~adapt.AdaptersMap

    The adapters configuration used to convert Python parameters and
    PostgreSQL results for the queries executed on this cursor.

    It affects all the cursors created by this connection afterwards.

.. automethod:: close

    .. note::

        You can use::

            with psycopg.connect() as conn:
                ...

        to close the connection automatically when the block is exited.
        See :ref:`with-connection`.

.. autoattribute:: closed
.. autoattribute:: broken

.. method:: cursor(*, binary: bool = False, \
       row_factory: Optional[RowFactory] = None) -> Cursor
.. method:: cursor(name: str, *, binary: bool = False, \
        row_factory: Optional[RowFactory] = None, \
        scrollable: Optional[bool] = None, withhold: bool = False) -> ServerCursor
    :noindex:

    Return a new cursor to send commands and queries to the connection.

    :param name: If not specified create a client-side cursor, if
                 specified create a server-side cursor. See
                 :ref:`cursor-types` for details.
    :param binary: If `!True` return binary values from the database. All
                   the types returned by the query must have a binary
                   loader. See :ref:`binary-data` for details.
    :param row_factory: If specified override the `row_factory` set on the
                        connection. See :ref:`row-factories` for details.
    :param scrollable: Specify the `~ServerCursor.scrollable` property of
                       the server-side cursor created.
    :param withhold: Specify the `~ServerCursor.withhold` property of
                     the server-side cursor created.
    :return: A cursor of the class specified by `cursor_factory` (or
             `server_cursor_factory` if `!name` is specified).

    .. note::

        You can use::

            with conn.cursor() as cur:
                ...

        to close the cursor automatically when the block is exited.

.. autoattribute:: cursor_factory

    The type, or factory function, returned by `cursor()` and `execute()`.

    Default is `psycopg.Cursor`.

.. autoattribute:: server_cursor_factory

    The type, or factory function, returned by `cursor()` when a name is
    specified.

    Default is `psycopg.ServerCursor`.

.. autoattribute:: row_factory

    The row factory defining the type of rows returned by
    `~Cursor.fetchone()` and the other cursor fetch methods.

    The default is `~psycopg.rows.tuple_row`, which means that the fetch
    methods will return simple tuples.

    .. seealso:: See :ref:`row-factories` for details about defining the
        objects returned by cursors.

.. automethod:: execute

    :param query: The query to execute.
    :type query: `~typing.LiteralString`, `!bytes`, `sql.SQL`, `sql.Composed`,
        or `~string.templatelib.Template`
    :param params: The parameters to pass to the query, if any.
        Can't be specified if ``query`` is a `!Template`.
    :type params: Sequence or Mapping
    :param prepare: Force (`!True`) or disallow (`!False`) preparation of
        the query. By default (`!None`) prepare automatically. See
        :ref:`prepared-statements`.
    :param binary: If `!True` the cursor will return binary values from the
        database. All the types returned by the query must have a binary
        loader. See :ref:`binary-data` for details.

    The method simply creates a `Cursor` instance, `~Cursor.execute()` the
    query requested, and returns it.

    See :ref:`query-parameters` for all the details about executing
    queries.

.. automethod:: pipeline

    The method is a context manager: you should call it using::

        with conn.pipeline() as p:
            ...

    At the end of the block, a synchronization point is established and
    the connection returns in normal mode.

    You can call the method recursively from within a pipeline block.
    Innermost blocks will establish a synchronization point on exit, but
    pipeline mode will be kept until the outermost block exits.

    See :ref:`pipeline-mode` for details.

    .. versionadded:: 3.1


.. rubric:: Transaction management methods

For details see :ref:`transactions`.

.. automethod:: commit
.. automethod:: rollback
.. automethod:: transaction

    .. note::

        The method must be called with a syntax such as::

            with conn.transaction():
                ...

            with conn.transaction() as tx:
                ...

        The latter is useful if you need to interact with the
        `Transaction` object. See :ref:`transaction-context` for details.

    Inside a transaction block it will not be possible to call `commit()`
    or `rollback()`.

.. autoattribute:: autocommit

    The property is writable for sync connections, read-only for async
    ones: you should call `!await` `~AsyncConnection.set_autocommit`
    :samp:`({value})` instead.

.. automethod:: set_autocommit

    .. versionadded:: 3.2

The following three properties control the characteristics of new
transactions. See :ref:`transaction-characteristics` for details.

.. autoattribute:: isolation_level

    `!None` means use the default set in the default_transaction_isolation__
    configuration parameter of the server.

    .. __: https://www.postgresql.org/docs/current/runtime-config-client.html
           #GUC-DEFAULT-TRANSACTION-ISOLATION

.. automethod:: set_isolation_level

    .. versionadded:: 3.2

.. autoattribute:: read_only

    `!None` means use the default set in the default_transaction_read_only__
    configuration parameter of the server.

    .. __: https://www.postgresql.org/docs/current/runtime-config-client.html
           #GUC-DEFAULT-TRANSACTION-READ-ONLY

.. automethod:: set_read_only

    .. versionadded:: 3.2

.. autoattribute:: deferrable

    `!None` means use the default set in the default_transaction_deferrable__
    configuration parameter of the server.

    .. __: https://www.postgresql.org/docs/current/runtime-config-client.html
           #GUC-DEFAULT-TRANSACTION-DEFERRABLE

.. automethod:: set_deferrable

    .. versionadded:: 3.2


.. rubric:: Checking and configuring the connection state

.. attribute:: pgconn
    :type: psycopg.pq.PGconn

    The `~pq.PGconn` libpq connection wrapper underlying the `!Connection`.

    It can be used to send low level commands to PostgreSQL and access
    features not currently wrapped by Psycopg.

.. autoattribute:: info

.. autoattribute:: prepare_threshold

    See :ref:`prepared-statements` for details.


.. autoattribute:: prepared_max

    If more queries need to be prepared, old ones are deallocated__.

    Specifying `!None` can be useful for middleware that don't support
    deallocation; see :ref:`prepared statements notes <pgbouncer>`.

    .. __: https://www.postgresql.org/docs/current/sql-deallocate.html

    .. versionchanged:: 3.2

        Added support for the `!None` value.


.. rubric:: Methods you can use to do something cool

.. automethod:: cancel_safe

    .. note::

        You can use the `~Capabilities.has_cancel_safe` capability to check
        if `!cancel_safe()` will not fall back on the legacy libpq
        functions.

    .. warning::

        The `timeout` parameter has no effect for libpq older than version
        17.

    .. warning::

        This method shouldn't be used as a `~signal.signal` handler.
        Please use `cancel()` instead.

    .. versionadded:: 3.2

.. automethod:: cancel

    .. warning::

        The `!cancel()` method is implemented using the :pq:`PQcancel`
        function, which is deprecated since PostgreSQL 17, and has a few
        shortcomings:

        - it is blocking even on async connections,
        - it `might use an insecure connection`__ even if the original
          connection was secure.

        Therefore you should use the `cancel_safe()` method whenever
        possible.

        .. __: https://www.postgresql.org/docs/devel/libpq-cancel.html
               #LIBPQ-CANCEL-DEPRECATED

    .. note::

        Unlike `cancel_safe()`, it is safe to call this method as a
        `~signal.signal` handler. This is pretty much the only case in
        which you might want to use this function.

.. automethod:: notifies

    Notifies are received after using :sql:`LISTEN` in a connection, when
    any sessions in the database generates a :sql:`NOTIFY` on one of the
    listened channels.

    .. versionchanged:: 3.2

        Added `!timeout` and `!stop_after` parameters.

.. automethod:: add_notify_handler

    See :ref:`async-notify` for details.

.. automethod:: remove_notify_handler

.. automethod:: add_notice_handler

    See :ref:`async-messages` for details.

.. automethod:: remove_notice_handler

.. automethod:: fileno


.. _tpc-methods:

.. rubric:: Two-Phase Commit support methods

.. versionadded:: 3.1

.. seealso:: :ref:`two-phase-commit` for an introductory explanation of
    these methods.

.. automethod:: xid

.. automethod:: tpc_begin

    :param xid: The id of the transaction
    :type xid: Xid or str

    This method should be called outside of a transaction (i.e. nothing
    may have executed since the last `commit()` or `rollback()` and
    `~ConnectionInfo.transaction_status` is `~pq.TransactionStatus.IDLE`).

    Furthermore, it is an error to call `!commit()` or `!rollback()`
    within the TPC transaction: in this case a `ProgrammingError`
    is raised.

    The `!xid` may be either an object returned by the `xid()` method or a
    plain string: the latter allows to create a transaction using the
    provided string as PostgreSQL transaction id. See also
    `tpc_recover()`.


.. automethod:: tpc_prepare

    A `ProgrammingError` is raised if this method is used outside of a TPC
    transaction.

    After calling `!tpc_prepare()`, no statements can be executed until
    `tpc_commit()` or `tpc_rollback()` will be
    called.

    .. seealso:: The |PREPARE TRANSACTION|_ PostgreSQL command.

    .. |PREPARE TRANSACTION| replace:: :sql:`PREPARE TRANSACTION`
    .. _PREPARE TRANSACTION: https://www.postgresql.org/docs/current/static/sql-prepare-transaction.html


.. automethod:: tpc_commit

    :param xid: The id of the transaction
    :type xid: Xid or str

    When called with no arguments, `!tpc_commit()` commits a TPC
    transaction previously prepared with `tpc_prepare()`.

    If `!tpc_commit()` is called prior to `!tpc_prepare()`, a single phase
    commit is performed.  A transaction manager may choose to do this if
    only a single resource is participating in the global transaction.

    When called with a transaction ID `!xid`, the database commits the
    given transaction.  If an invalid transaction ID is provided, a
    `ProgrammingError` will be raised.  This form should be called outside
    of a transaction, and is intended for use in recovery.

    On return, the TPC transaction is ended.

    .. seealso:: The |COMMIT PREPARED|_ PostgreSQL command.

    .. |COMMIT PREPARED| replace:: :sql:`COMMIT PREPARED`
    .. _COMMIT PREPARED: https://www.postgresql.org/docs/current/static/sql-commit-prepared.html


.. automethod:: tpc_rollback

    :param xid: The id of the transaction
    :type xid: Xid or str

    When called with no arguments, `!tpc_rollback()` rolls back a TPC
    transaction.  It may be called before or after `tpc_prepare()`.

    When called with a transaction ID `!xid`, it rolls back the given
    transaction.  If an invalid transaction ID is provided, a
    `ProgrammingError` is raised.  This form should be called outside of a
    transaction, and is intended for use in recovery.

    On return, the TPC transaction is ended.

    .. seealso:: The |ROLLBACK PREPARED|_ PostgreSQL command.

    .. |ROLLBACK PREPARED| replace:: :sql:`ROLLBACK PREPARED`
    .. _ROLLBACK PREPARED: https://www.postgresql.org/docs/current/static/sql-rollback-prepared.html


.. automethod:: tpc_recover

    Returns a list of `Xid` representing pending transactions, suitable
    for use with `tpc_commit()` or `tpc_rollback()`.

    If a transaction was not initiated by Psycopg, the returned Xids will
    have attributes `~Xid.format_id` and `~Xid.bqual` set to `!None` and
    the `~Xid.gtrid` set to the PostgreSQL transaction ID: such Xids are
    still usable for recovery.  Psycopg uses the same algorithm of the
    `PostgreSQL JDBC driver`__ to encode a XA triple in a string, so
    transactions initiated by a program using such driver should be
    unpacked correctly.

    .. __: https://jdbc.postgresql.org/

    Xids returned by `!tpc_recover()` also have extra attributes
    `~Xid.prepared`, `~Xid.owner`, `~Xid.database` populated with the
    values read from the server.

    .. seealso:: the |pg_prepared_xacts|_ system view.

    .. |pg_prepared_xacts| replace:: `pg_prepared_xacts`
    .. _pg_prepared_xacts: https://www.postgresql.org/docs/current/static/view-pg-prepared-xacts.html

This class implements a DBAPI-inspired interface, with all the blocking
methods implemented as coroutines. Unless specified otherwise,
non-blocking methods are shared with the `Connection` class.

The following methods have the same behaviour of the matching `!Connection`
methods, but should be called using the `await` keyword.

.. automethod:: connect

    .. versionchanged:: 3.1

        Automatically resolve domain names asynchronously. In previous
        versions, name resolution blocks, unless the `!hostaddr`
        parameter is specified, or the `~psycopg._dns.resolve_hostaddr_async()`
        function is used.

.. automethod:: close

    .. note:: You can use ``async with`` to close the connection
        automatically when the block is exited, but be careful about
        the async quirkness: see :ref:`async-with` for details.

.. method:: cursor(*, binary: bool = False, \
        row_factory: Optional[RowFactory] = None) -> AsyncCursor
.. method:: cursor(name: str, *, binary: bool = False, \
        row_factory: Optional[RowFactory] = None, \
        scrollable: Optional[bool] = None, withhold: bool = False) -> AsyncServerCursor
    :noindex:

    .. note::

        You can use::

            async with conn.cursor() as cur:
                ...

        to close the cursor automatically when the block is exited.

.. autoattribute:: cursor_factory

    Default is `psycopg.AsyncCursor`.

.. autoattribute:: server_cursor_factory

    Default is `psycopg.AsyncServerCursor`.

.. autoattribute:: row_factory

.. automethod:: execute

.. automethod:: pipeline

    .. note::

        It must be called as::

            async with conn.pipeline() as p:
                ...

.. automethod:: commit
.. automethod:: rollback

.. automethod:: transaction

    .. note::

        It must be called as::

            async with conn.transaction() as tx:
                ...

.. automethod:: cancel_safe

    .. versionadded:: 3.2

.. automethod:: notifies

    .. versionchanged:: 3.2

        Added `!timeout` and `!stop_after` parameters.

.. automethod:: set_autocommit
.. automethod:: set_isolation_level
.. automethod:: set_read_only
.. automethod:: set_deferrable

.. automethod:: tpc_prepare
.. automethod:: tpc_commit
.. automethod:: tpc_rollback
.. automethod:: tpc_recover