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For library end users, there is no need to install tests alongside the package itself. This keeps the tests available for development without adding extra packages to user's site-packages directory. Reduces the size of the installed package. Avoids accidental execution of test code by an installed package.
310 lines
9.3 KiB
ReStructuredText
310 lines
9.3 KiB
ReStructuredText
Introduction
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============
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.. sectionauthor:: Daniele Varrazzo <daniele.varrazzo@gmail.com>
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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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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 an experimental `porting of Psycopg for Ctypes`__, but it is not as
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mature as the C implementation yet.
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The current `!psycopg2` implementation supports:
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..
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NOTE: keep consistent with setup.py and the /features/ page.
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- Python version 2.7
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- Python 3 versions from 3.4 to 3.6
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- PostgreSQL server versions from 7.4 to 10
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- PostgreSQL client library version from 9.1
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.. _PostgreSQL: http://www.postgresql.org/
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.. _Python: http://www.python.org/
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.. _libpq: http://www.postgresql.org/docs/current/static/libpq.html
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.. _CPython: http://en.wikipedia.org/wiki/CPython
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.. _Ctypes: http://docs.python.org/library/ctypes.html
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.. __: https://github.com/mvantellingen/psycopg2-ctypes
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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 install from PyPI
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------------------------
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`!psycopg2` is `available on PyPI`__ in the form of wheel_ packages for the
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most common platform (Linux, OSX, Windows): this should make you able to
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install a binary version of the module including all the dependencies simply
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using:
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.. code-block:: console
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$ pip install psycopg2
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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``)
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.. __: PyPI_
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.. _PyPI: https://pypi.python.org/pypi/psycopg2/
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.. _wheel: http://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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.. warning::
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Because the `!psycopg` wheel package uses its own ``libssl`` binary, it is
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incompatible with other extension modules binding with ``libssl`` as well,
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for instance the Python `ssl` module: the result will likely be a
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segfault. If you need using both `!psycopg2` and other libraries using
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``libssl`` please :ref:`disable the use of wheel packages for Psycopg
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<disable-wheel>`.
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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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Disabling wheel packages
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^^^^^^^^^^^^^^^^^^^^^^^^
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If you want to disable the use of wheel binary packages and use the system
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system libraries available on your client you can use the :command:`pip`
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|--no-binary option|__:
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.. code-block:: console
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$ pip install --no-binary 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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single: Install; from source
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.. _install-from-source:
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Install from source
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-------------------
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.. _source-package:
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You can download a copy of Psycopg source files from the `Psycopg download
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page`__ or from PyPI_.
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.. __: http://initd.org/psycopg/download/
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.. _build-prerequisites:
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Build prerequisites
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^^^^^^^^^^^^^^^^^^^
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These notes illustrate how to compile Psycopg on Linux. If you want to compile
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Psycopg on other platforms you may have to adjust some details accordingly.
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Psycopg is a C wrapper around the libpq_ PostgreSQL client library. To install
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it from sources you will need:
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- A C compiler.
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- The Python header files. They are usually installed in a package such as
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**python-dev**. A message such as *error: Python.h: No such file or
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directory* is an indication that the Python headers are missing.
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- The libpq header files. They are usually installed in a package such as
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**libpq-dev**. If you get an *error: libpq-fe.h: No such file or directory*
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you are missing them.
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- The :program:`pg_config` program: it is usually installed by the
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**libpq-dev** package but sometimes it is not in a :envvar:`PATH` directory.
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Having it in the :envvar:`PATH` greatly streamlines the installation, so try
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running ``pg_config --version``: if it returns an error or an unexpected
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version number then locate the directory containing the :program:`pg_config`
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shipped with the right libpq version (usually
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``/usr/lib/postgresql/X.Y/bin/``) and add it to the :envvar:`PATH`:
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.. code-block:: console
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$ export PATH=/usr/lib/postgresql/X.Y/bin/:$PATH
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You only need :program:`pg_config` to compile `!psycopg2`, not for its
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regular usage.
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Once everything is in place it's just a matter of running the standard:
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.. code-block:: console
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$ python setup.py build
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$ python setup.py install
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Runtime requirements
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^^^^^^^^^^^^^^^^^^^^
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Unless you compile `!psycopg2` as a static library, or you install it from a
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self-contained wheel package, it will need the libpq_ library at runtime
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(usually distributed in a ``libpq.so`` or ``libpq.dll`` file). `!psycopg2`
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relies on the host OS to find the library if the library is installed in a
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standard location there is usually no problem; if the library is in a
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non-standard location you will have to tell somehow Psycopg how to find it,
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which is OS-dependent (for instance setting a suitable
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:envvar:`LD_LIBRARY_PATH` on Linux).
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.. note::
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The libpq header files used to compile `!psycopg2` should match the
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version of the library linked at runtime. If you get errors about missing
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or mismatching libraries when importing `!psycopg2` check (e.g. using
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:program:`ldd`) if the module ``psycopg2/_psycopg.so`` is linked to the
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right ``libpq.so``.
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.. note::
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Whatever version of libpq `!psycopg2` is compiled with, it will be
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possible to connect to PostgreSQL servers of any supported version: just
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install the most recent libpq version or the most practical, without
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trying to match it to the version of the PostgreSQL server you will have
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to connect to.
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.. index::
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single: setup.py
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single: setup.cfg
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Non-standard builds
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^^^^^^^^^^^^^^^^^^^
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If you have less standard requirements such as:
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- creating a :ref:`debug build <debug-build>`,
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- using :program:`pg_config` not in the :envvar:`PATH`,
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- supporting ``mx.DateTime``,
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then take a look at the ``setup.cfg`` file.
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Some of the options available in ``setup.cfg`` are also available as command
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line arguments of the ``build_ext`` sub-command. For instance you can specify
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an alternate :program:`pg_config` location using:
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.. code-block:: console
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$ python setup.py build_ext --pg-config /path/to/pg_config build
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Use ``python setup.py build_ext --help`` to get a list of the options
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supported.
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.. index::
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single: debug
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single: PSYCOPG_DEBUG
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.. _debug-build:
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Creating a debug build
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^^^^^^^^^^^^^^^^^^^^^^
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In case of problems, Psycopg can be configured to emit detailed debug
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messages, which can be very useful for diagnostics and to report a bug. In
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order to create a debug package:
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- `Download`__ and unpack the Psycopg source package.
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- Edit the ``setup.cfg`` file adding the ``PSYCOPG_DEBUG`` flag to the
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``define`` option.
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- :ref:`Compile and install <source-package>` the package.
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- Set the :envvar:`PSYCOPG_DEBUG` environment variable:
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.. code-block:: console
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$ export PSYCOPG_DEBUG=1
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- Run your program (making sure that the `!psycopg2` package imported is the
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one you just compiled and not e.g. the system one): you will have a copious
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stream of informations printed on stderr.
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.. __: http://initd.org/psycopg/download/
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.. index::
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single: tests
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.. _test-suite:
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Running the test suite
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----------------------
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Once `!psycopg2` is installed you can run the test suite to verify it is
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working correctly. From the source directory, you can run:
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.. code-block:: console
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$ python -c "import tests; tests.unittest.main(defaultTest='tests.test_suite')" --verbose
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The tests run against a database called ``psycopg2_test`` on UNIX socket and
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the standard port. You can configure a different database to run the test by
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setting the environment variables:
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- :envvar:`PSYCOPG2_TESTDB`
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- :envvar:`PSYCOPG2_TESTDB_HOST`
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- :envvar:`PSYCOPG2_TESTDB_PORT`
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- :envvar:`PSYCOPG2_TESTDB_USER`
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The database should already exist before running the tests.
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.. _other-problems:
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If you still have problems
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--------------------------
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Try the following. *In order:*
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- Read again the :ref:`build-prerequisites`.
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- Read the :ref:`FAQ <faq-compile>`.
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- Google for `!psycopg2` *your error message*. Especially useful the week
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after the release of a new OS X version.
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- Write to the `Mailing List`__.
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- Complain on your blog or on Twitter that `!psycopg2` is the worst package
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ever and about the quality time you have wasted figuring out the correct
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:envvar:`ARCHFLAGS`. Especially useful from the Starbucks near you.
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.. __: https://lists.postgresql.org/mj/mj_wwwusr?func=lists-long-full&extra=psycopg
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