mirror of
https://github.com/psycopg/psycopg2.git
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Merge branch 'docs/quick-start'
This commit is contained in:
Daniele Varrazzo
commit
90e8c80ed1
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@ -8,27 +8,117 @@ Installation
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Psycopg is a PostgreSQL_ adapter for the Python_ programming language. It is a
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Psycopg is a PostgreSQL_ adapter for the Python_ programming language. It is a
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wrapper for the libpq_, the official PostgreSQL client library.
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wrapper for the libpq_, the official PostgreSQL client library.
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The `psycopg2` package is the current mature implementation of the adapter: it
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is a C extension and as such it is only compatible with CPython_. If you want
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to use Psycopg on a different Python implementation (PyPy, Jython, IronPython)
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there is a couple of alternative:
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- a `Ctypes port`__, but it is not as mature as the C implementation yet
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and it is not as feature-complete;
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- a `CFFI port`__ which is currently more used and reported more efficient on
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PyPy, but please be careful of its version numbers because they are not
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aligned to the official psycopg2 ones and some features may differ.
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.. _PostgreSQL: https://www.postgresql.org/
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.. _PostgreSQL: https://www.postgresql.org/
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.. _Python: https://www.python.org/
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.. _Python: https://www.python.org/
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.. _libpq: https://www.postgresql.org/docs/current/static/libpq.html
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.. _CPython: https://en.wikipedia.org/wiki/CPython
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.. _Ctypes: https://docs.python.org/library/ctypes.html
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.. __: https://github.com/mvantellingen/psycopg2-ctypes
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.. __: https://github.com/chtd/psycopg2cffi
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.. index::
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single: Install; from PyPI
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single: Install; wheel
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single: Wheel
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.. _binary-packages:
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Quick Install
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-------------
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For most operating systems, the quickest way to install Psycopg is using the
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wheel_ package available on PyPI_:
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.. code-block:: console
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$ pip install psycopg2-binary
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This will install a pre-compiled binary version of the module which does not
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require the build or runtime prerequisites described below. Make sure to use
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an up-date-date version of :program:`pip` (you can upgrade it using something
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like ``pip install -U pip``).
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You may then import the ``psycopg`` package, as usual:
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.. code-block:: python
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import psycopg
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# Connect to your postgres DB
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conn = psycopg.connect("dbname=test user=postgres")
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# Open a cursor to perform database operations
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cur = conn.cursor()
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# Execute a query
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cur.execute("SELECT * FROM my_data");
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# Retrieve query results
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records = cur.fetchall()
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.. _PyPI: https://pypi.org/project/psycopg2-binary/
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.. _wheel: https://pythonwheels.com/
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psycopg vs psycopg-binary
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^^^^^^^^^^^^^^^^^^^^^^^^^
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The ``psycopg2-binary`` package is meant for beginners to start playing
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with Python and PostgreSQL without the need to meet the build
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requirements.
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If you are the maintainer of a published package depending on `!psycopg2`
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you shouldn't use ``psycopg2-binary`` as a module dependency. **For
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production use you are advised to use the source distribution.**
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The binary packages come with their own versions of a few C libraries,
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among which ``libpq`` and ``libssl``, which will be used regardless of other
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libraries available on the client: upgrading the system libraries will not
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upgrade the libraries used by `!psycopg2`. Please build `!psycopg2` from
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source if you want to maintain binary upgradeability.
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.. warning::
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The `!psycopg2` wheel package comes packaged, among the others, with its
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own ``libssl`` binary. This may create conflicts with other extension
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modules binding with ``libssl`` as well, for instance with the Python
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`ssl` module: in some cases, under concurrency, the interaction between
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the two libraries may result in a segfault. In case of doubts you are
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advised to use a package built from source.
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.. index::
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single: Install; disable wheel
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single: Wheel; disable
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.. _disable-wheel:
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Change in binary packages between Psycopg 2.7 and 2.8
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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In version 2.7.x, :command:`pip install psycopg2` would have tried to install
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automatically the binary package of Psycopg. Because of concurrency problems
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binary packages have displayed, ``psycopg2-binary`` has become a separate
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package, and from 2.8 it has become the only way to install the binary
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package.
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If you are using Psycopg 2.7 and you want to disable the use of wheel binary
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packages, relying on the system libraries available on your client, you
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can use the :command:`pip` |--no-binary option|__, e.g.:
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.. code-block:: console
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$ pip install --no-binary :all: psycopg2
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.. |--no-binary option| replace:: ``--no-binary`` option
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.. __: https://pip.pypa.io/en/stable/reference/pip_install/#install-no-binary
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which can be specified in your :file:`requirements.txt` files too, e.g. use:
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.. code-block:: none
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psycopg2>=2.7,<2.8 --no-binary psycopg2
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to use the last bugfix release of the `!psycopg2` 2.7 package, specifying to
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always compile it from source. Of course in this case you will have to meet
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the :ref:`build prerequisites <build-prerequisites>`.
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.. index::
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.. index::
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single: Prerequisites
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single: Prerequisites
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@ -130,101 +220,6 @@ which is OS-dependent (for instance setting a suitable
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to connect to.
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to connect to.
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.. index::
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single: Install; from PyPI
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single: Install; wheel
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single: Wheel
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.. _binary-packages:
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Binary install from PyPI
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------------------------
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`!psycopg2` is also `available on PyPI`__ in the form of wheel_ packages for
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the most common platform (Linux, OSX, Windows): this should make you able to
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install a binary version of the module, not requiring the above build or
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runtime prerequisites.
|
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|
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.. note::
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|
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The ``psycopg2-binary`` package is meant for beginners to start playing
|
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with Python and PostgreSQL without the need to meet the build
|
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requirements.
|
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|
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If you are the maintainer of a published package depending on `!psycopg2`
|
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**you shouldn't use 'psycopg2-binary' as a module dependency**. For
|
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production use you are advised to use the source distribution.
|
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|
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|
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Make sure to use an up-to-date version of :program:`pip` (you can upgrade it
|
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using something like ``pip install -U pip``), then you can run:
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|
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.. code-block:: console
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$ pip install psycopg2-binary
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.. __: PyPI-binary_
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.. _PyPI-binary: https://pypi.org/project/psycopg2-binary/
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.. _wheel: https://pythonwheels.com/
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.. note::
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The binary packages come with their own versions of a few C libraries,
|
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among which ``libpq`` and ``libssl``, which will be used regardless of other
|
|
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libraries available on the client: upgrading the system libraries will not
|
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upgrade the libraries used by `!psycopg2`. Please build `!psycopg2` from
|
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source if you want to maintain binary upgradeability.
|
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|
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.. warning::
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|
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The `!psycopg2` wheel package comes packaged, among the others, with its
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own ``libssl`` binary. This may create conflicts with other extension
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modules binding with ``libssl`` as well, for instance with the Python
|
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`ssl` module: in some cases, under concurrency, the interaction between
|
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the two libraries may result in a segfault. In case of doubts you are
|
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advised to use a package built from source.
|
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|
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.. index::
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single: Install; disable wheel
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single: Wheel; disable
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.. _disable-wheel:
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Change in binary packages between Psycopg 2.7 and 2.8
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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|
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|
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In version 2.7.x, :command:`pip install psycopg2` would have tried to install
|
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automatically the binary package of Psycopg. Because of concurrency problems
|
|
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binary packages have displayed, ``psycopg2-binary`` has become a separate
|
|
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package, and from 2.8 it has become the only way to install the binary
|
|
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package.
|
|
||||||
|
|
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If you are using Psycopg 2.7 and you want to disable the use of wheel binary
|
|
||||||
packages, relying on the system libraries available on your client, you
|
|
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can use the :command:`pip` |--no-binary option|__, e.g.:
|
|
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|
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.. code-block:: console
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|
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$ pip install --no-binary :all: psycopg2
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|
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.. |--no-binary option| replace:: ``--no-binary`` option
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.. __: https://pip.pypa.io/en/stable/reference/pip_install/#install-no-binary
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|
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which can be specified in your :file:`requirements.txt` files too, e.g. use:
|
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|
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.. code-block:: none
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|
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psycopg2>=2.7,<2.8 --no-binary psycopg2
|
|
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|
|
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to use the last bugfix release of the `!psycopg2` 2.7 package, specifying to
|
|
||||||
always compile it from source. Of course in this case you will have to meet
|
|
||||||
the :ref:`build prerequisites <build-prerequisites>`.
|
|
||||||
|
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||||||
|
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||||||
|
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.. index::
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.. index::
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single: setup.py
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single: setup.py
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single: setup.cfg
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single: setup.cfg
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@ -286,6 +281,29 @@ order to create a debug package:
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.. __: https://pypi.org/project/psycopg2/#files
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.. __: https://pypi.org/project/psycopg2/#files
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|
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Non-standard Python Implementation
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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|
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|
The `psycopg2` package is the current mature implementation of the adapter: it
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||||||
|
is a C extension and as such it is only compatible with CPython_. If you want
|
||||||
|
to use Psycopg on a different Python implementation (PyPy, Jython, IronPython)
|
||||||
|
there is a couple of alternative:
|
||||||
|
|
||||||
|
- a `Ctypes port`__, but it is not as mature as the C implementation yet
|
||||||
|
and it is not as feature-complete;
|
||||||
|
|
||||||
|
- a `CFFI port`__ which is currently more used and reported more efficient on
|
||||||
|
PyPy, but please be careful of its version numbers because they are not
|
||||||
|
aligned to the official psycopg2 ones and some features may differ.
|
||||||
|
|
||||||
|
.. _PostgreSQL: https://www.postgresql.org/
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|
.. _Python: https://www.python.org/
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|
.. _libpq: https://www.postgresql.org/docs/current/static/libpq.html
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|
.. _CPython: https://en.wikipedia.org/wiki/CPython
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.. _Ctypes: https://docs.python.org/library/ctypes.html
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.. __: https://github.com/mvantellingen/psycopg2-ctypes
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|
.. __: https://github.com/chtd/psycopg2cffi
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|
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||||||
|
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||||||
.. index::
|
.. index::
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||||||
single: tests
|
single: tests
|
||||||
|
|
@ -314,7 +332,6 @@ setting the environment variables:
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The database should already exist before running the tests.
|
The database should already exist before running the tests.
|
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|
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|
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.. _other-problems:
|
.. _other-problems:
|
||||||
|
|
||||||
If you still have problems
|
If you still have problems
|
||||||
|
|
|
||||||
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