Installation — PyGreSQL 5.1

# Installation

## General

You must first install Python and PostgreSQL on your system. If you want to access remote databases only, you don’t need to install the full PostgreSQL server, but only the libpq C-interface library. If you are on Windows, make sure that the directory that contains libpq.dll is part of your `PATH` environment variable.

The current version of PyGreSQL has been tested with Python versions 2.6, 2.7 and 3.3 to 3.7, and PostgreSQL versions 9.0 to 9.6 and 10 or 11.

PyGreSQL will be installed as three modules, a shared library called _pg.so (on Linux) or a DLL called _pg.pyd (on Windows), and two pure Python wrapper modules called pg.py and pgdb.py. All three files will be installed directly into the Python site-packages directory. To uninstall PyGreSQL, simply remove these three files.

## Installing with Pip

This is the most easy way to install PyGreSQL if you have “pip” installed. Just run the following command in your terminal:

    pip install PyGreSQL

This will automatically try to find and download a distribution on the Python Package Index that matches your operating system and Python version and install it.

## Installing from a Binary Distribution

If you don’t want to use “pip”, or “pip” doesn’t find an appropriate distribution for your computer, you can also try to manually download and install a distribution.

When you download the source distribution, you will need to compile the C extension, for which you need a C compiler installed. If you don’t want to install a C compiler or avoid possible problems with the compilation, you can search for a pre-compiled binary distribution of PyGreSQL on the Python Package Index or the PyGreSQL homepage.

You can currently download PyGreSQL as Linux RPM, NetBSD package and Windows installer. Make sure the required Python version of the binary package matches the Python version you have installed.

Install the package as usual on your system.

Note that the documentation is currently only included in the source package.

## Installing from Source

If you want to install PyGreSQL from Source, or there is no binary package available for your platform, follow these instructions.

Make sure the Python header files and PostgreSQL client and server header files are installed. These come usually with the “devel” packages on Unix systems and the installer executables on Windows systems.

If you are using a precompiled PostgreSQL, you will also need the pg_config tool. This is usually also part of the “devel” package on Unix, and will be installed as part of the database server feature on Windows systems.

### Building and installing with Distutils

You can build and install PyGreSQL using Distutils.

Download and unpack the PyGreSQL source tarball if you haven’t already done so.

Type the following commands to build and install PyGreSQL:

    python setup.py build
    python setup.py install

Now you should be ready to use PyGreSQL.

### Compiling Manually

The source file for compiling the C extension module is pgmodule.c. You have two options. You can compile PyGreSQL as a stand-alone module or you can build it into the Python interpreter.

#### Stand-Alone

- In the directory containing `pgmodule.c`, run the following command:

      cc -fpic -shared -o _pg.so -I$PYINC -I$PGINC -I$PSINC -L$PGLIB -lpq pgmodule.c

  where you have to set:

      PYINC = path to the Python include files
              (usually something like /usr/include/python)
      PGINC = path to the PostgreSQL client include files
              (something like /usr/include/pgsql or /usr/include/postgresql)
      PSINC = path to the PostgreSQL server include files
              (like /usr/include/pgsql/server or /usr/include/postgresql/server)
      PGLIB = path to the PostgreSQL object code libraries (usually /usr/lib)

  If you are not sure about the above paths, try something like:

      PYINC=`find /usr -name Python.h`
      PGINC=`find /usr -name libpq-fe.h`
      PSINC=`find /usr -name postgres.h`
      PGLIB=`find /usr -name libpq.so`

  If you have the `pg_config` tool installed, you can set:

      PGINC=`pg_config --includedir`
      PSINC=`pg_config --includedir-server`
      PGLIB=`pg_config --libdir`

  Some options may be added to this line:

      -DNO_DEF_VAR   no default variables support
      -DNO_DIRECT    no direct access methods
      -DNO_LARGE     no large object support
      -DNO_PQSOCKET  if running an older PostgreSQL

  On some systems you may need to include `-lcrypt` in the list of libraries to make it compile.

- Test the new module. Something like the following should work:

      $ python

      >>> import _pg
      >>> db = _pg.connect('thilo','localhost')
      >>> db.query("INSERT INTO test VALUES ('ping','pong')")
      18304
      >>> db.query("SELECT * FROM test")
      eins|zwei
      ----+----
      ping|pong
      (1 row)

- Finally, move the `_pg.so`, `pg.py`, and `pgdb.py` to a directory in your `PYTHONPATH`. A good place would be `/usr/lib/python/site-packages` if your Python modules are in `/usr/lib/python`.

#### Built-in to Python interpreter

- Find the directory where your `Setup` file lives (usually in the `Modules` subdirectory) in the Python source hierarchy and copy or symlink the `pgmodule.c` file there.

- Add the following line to your ‘Setup’ file:

      _pg  pgmodule.c -I$PGINC -I$PSINC -L$PGLIB -lpq

  where:

      PGINC = path to the PostgreSQL client include files (see above)
      PSINC = path to the PostgreSQL server include files (see above)
      PGLIB = path to the PostgreSQL object code libraries (see above)

  Some options may be added to this line:

      -DNO_DEF_VAR   no default variables support
      -DNO_DIRECT    no direct access methods
      -DNO_LARGE     no large object support
      -DNO_PQSOCKET  if running an older PostgreSQL (see above)

  On some systems you may need to include `-lcrypt` in the list of libraries to make it compile.

- If you want a shared module, make sure that the `shared` keyword is uncommented and add the above line below it. You used to need to install your shared modules with `make sharedinstall` but this no longer seems to be true.

- Copy `pg.py` to the lib directory where the rest of your modules are. For example, that’s `/usr/local/lib/Python` on my system.

- Rebuild Python from the root directory of the Python source hierarchy by running `make -f Makefile.pre.in boot` and `make && make install`.

- For more details read the documentation at the top of `Makefile.pre.in`.