psycopg2 package is the current mature implementation of the adapter: it
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 an experimental porting of Psycopg for Ctypes, but it is not as
mature as the C implementation yet.
psycopg2 implementation supports:
- Python 2 versions from 2.5 to 2.7
- Python 3 versions from 3.1 to 3.5
- PostgreSQL versions from 7.4 to 9.5
psycopg2 usually depends at runtime on the libpq dynamic library.
However it can connect to PostgreSQL servers of any supported version,
independently of the version of the libpq used: just install the most
recent libpq version or the most practical, without trying to match it to
the version of the PostgreSQL server you will have to connect to.
If possible, and usually it is, please install Psycopg from a package available for your distribution or operating system.
Compiling from source is a very easy task, however
psycopg2 is a C
extension module and as such it requires a few more things in place respect to
a pure Python module. So, if you don’t have experience compiling Python
extension packages, above all if you are a Windows or a Mac OS user, please
use a pre-compiled package and go straight to the module usage
avoid bothering with the gory details.
Regardless of the way
psycopg2 is installed, at runtime it will need to
use the libpq library.
psycopg2 relies on the host OS to find the
library file (usually
libpq.dll): if the library is
installed in a standard location there is usually no problem; if the
library is in a non-standard location you will have to tell somehow
psycopg how to find it, which is OS-dependent (for instance setting a
LD_LIBRARY_PATH on Linux).
Install from a package¶
Psycopg is available already packaged in many Linux distributions: look for a package such as
python-psycopg2using the package manager of your choice.
On Debian, Ubuntu and other deb-based distributions you should just need:
sudo apt-get install python-psycopg2
to install the package with all its dependencies.
- Mac OS X
Psycopg is available as a fink package in the unstable tree: you may install it with:
fink install psycopg2-py27
The library is also available on MacPorts try:
sudo port install py27-psycopg2
- Microsoft Windows
There are two options to install a precompiled
psycopg2package under windows:
Option 1: Using pip (Included in python 2.7.9+ and python 3.4+) and a binary wheel package. Launch windows’ command prompt (
cmd.exe) and execute the following command:
pip install psycopg2
Option 2: Jason Erickson maintains a packaged Windows port of Psycopg with installation executable. Download. Double click. Done.
Install from source¶
These notes illustrate how to compile Psycopg on Linux. If you want to compile Psycopg on other platforms you may have to adjust some details accordingly.
Psycopg is a C wrapper to the libpq PostgreSQL client library. To install it from sources you will need:
A C compiler.
The Python header files. They are usually installed in a package such as python-dev. A message such as error: Python.h: No such file or directory is an indication that the Python headers are missing.
The libpq header files. They are usually installed in a package such as libpq-dev. If you get an error: libpq-fe.h: No such file or directory you are missing them.
The pg_config program: it is usually installed by the libpq-dev package but sometimes it is not in a
PATHdirectory. Having it in the
PATHgreatly streamlines the installation, so try running
pg_config --version: if it returns an error or an unexpected version number then locate the directory containing the pg_config shipped with the right libpq version (usually
/usr/lib/postgresql/X.Y/bin/) and add it to the
$ export PATH=/usr/lib/postgresql/X.Y/bin/:$PATH
You only need it to compile and install
psycopg2, not for its regular usage.
The libpq header files used to compile
psycopg2 should match the
version of the library linked at runtime. If you get errors about missing
or mismatching libraries when importing
psycopg2 check (e.g. using
ldd) if the module
psycopg2/_psycopg.so is linked to the
Use a Python package manager¶
If the above requirements are satisfied, you can use easy_install, pip or whatever the Python package manager of the week:
$ pip install psycopg2
Please refer to your package manager documentation about performing a local or global installation, virtualenv (fully supported by recent Psycopg versions), using different Python versions and other nuances.
Use the source package¶
You can download a copy of Psycopg source files from the Psycopg download page. Once unpackaged, to compile and install the package you can run:
$ python setup.py build $ sudo python setup.py install
If you have less standard requirements such as:
- creating a debug build,
- using pg_config not in the
then take a look at the
Some of the options available in
setup.cfg are also available as command
line arguments of the
build_ext sub-command. For instance you can specify
an alternate pg_config version using:
$ python setup.py build_ext --pg-config /path/to/pg_config build
python setup.py build_ext --help to get a list of the options
Running the test suite¶
Makefile allows to run all the tests included in the
distribution. Just run:
make make check
The tests run against a database called
psycopg2_test on UNIX socket and
the standard port. You can configure a different database to run the test by
setting the environment variables:
The database should already exist before running the tests.
Creating a debug build¶
In case of problems, Psycopg can be configured to emit detailed debug messages, which can be very useful for diagnostics and to report a bug. In order to create a debug package:
Download and unpack the Psycopg source package.
setup.cfgfile adding the
PSYCOPG_DEBUGflag to the
Compile and install the package.
$ export PSYCOPG_DEBUG=1
Run your program (making sure that the
psycopg2package imported is the one you just compiled and not e.g. the system one): you will have a copious stream of informations printed on stderr.
If you still have problems¶
Try the following. In order:
- Read again the requirements.
- Read the FAQ.
- Google for
psycopg2your error message. Especially useful the week after the release of a new OS X version.
- Write to the Mailing List.
- Complain on your blog or on Twitter that
psycopg2is the worst package ever and about the quality time you have wasted figuring out the correct
ARCHFLAGS. Especially useful from the Starbucks near you.