MariaDB Connector/Python FAQ

MariaDB Connector/Python FAQ

This is a list of frequently asked questions about MariaDB Connector/Python. Feel free to suggest new entries!

Installation

Error: “Python.h: No such file or directory”

The header files and libraries of the Python development package weren’t properly installed. Use your package manager to install them system-wide:

Alpine (using apk):

sudo apk add python3-dev

Ubuntu/Debian (using apt):

sudo apt-get install python3-dev

CentOS/RHEL (using yum):

sudo yum install python3-devel

Fedora (using dnf):

sudo dnf install python3-devel

MacOSX (using homebrew):

brew install mariadb-connector-c

OpenSuse (using zypper):

sudo zypper in python3-devel

Note: The python3 development packages of your distribution might not cover all minor versions of python3. If you are using python3.10 you may need to install python3.10-dev.

ModuleNotFoundError: No module named ‘packaging’

With deprecation of distutils (see PEP-632) version functions of distutils module were replaced in MariaDB Connector/Python 1.1.5 by packaging version functions.

Before you can install MariaDB Connector/Python you have to install the packaging module:

pip3 install packaging

MariaDB Connector/Python requires MariaDB Connector/C >= 3.3.1, found version 3.1.2

The previously installed version of MariaDB Connector/C is too old and cannot be used for the MariaDB Connector/Python version you are trying to install.

To determine the installed version of MariaDB Connector/C, execute the command:

mariadb_config --cc_version

• Check if your distribution can be upgraded to a more recent version of MariaDB Connector/C, which fits the requirements.

• If your distribution doesn’t provide a recent version of MariaDB Connector/C, check the MariaDB Connector Download page, which provides latest versions for the major distributions.

• If none of the above will work for you, build and install MariaDB Connector/C from source.

OSError: mariadb_config not found

The mariadb_config program is used to retrieve configuration information (such as the location of header files and libraries, installed version, etc.) from MariaDB Connector/C.

This error indicates that MariaDB Connector/C, an important dependency for client/server communication that needs to be preinstalled, either was not installed or could not be found.

• If MariaDB Connector/C was previously installed, the installation script cannot detect the location of mariadb_config. Locate the directory where mariadb_config was installed and add this directory to your PATH.

  # locate mariadb_config
  sudo find / -name "mariadb_config"

• If MariaDB Connector/C was not installed and the location of mariadb_config couldn’t be detected, please install MariaDB Connector/C.

Error: struct st_mariadb_methods’ has no member named ‘db_execute_generate_request’

Even if the correct version of MariaDB Connector/C was installed, there are multiple mysql.h include files installed on your system, either from libmysql or an older MariaDB Connector/C installation. This can be checked by executing:

export CFLAGS="-V -E"
pip3 install mariadb > output.txt

Open output.txt in your favourite editor and search for “search starts here” where you can see the include files and paths used for the build.

Q: My distribution doesn’t provide a recent version of MariaDB Connector/C

If your distribution doesn’t provide a recent version of MariaDB Connector/C (required version is 3.3.1) you either can download a version of MariaDB Connector/C from the MariaDB Connector Download page or build the package from source:

mkdir bld
cd bld
cmake ..
make
make install

Q: Does MariaDB Connector/Python provide pre-releases or snapshot builds which contain recent bug fixes?

No. If an issue was fixed, the fix will be available in the next release via Python’s package manager repository (pypi.org).

Q: How can I build an actual version from github sources?

To build MariaDB Connector/Python from github sources, checkout latest sources from github:

git clone https://github.com/mariadb-corporation/mariadb-connector-python.git

and build and install it with:

python3 setup.py build
python3 -m pip install .

Connecting

mariadb.OperationalError: Can’t connect to local server through socket ‘/tmp/mysql.sock’

1. Check if MariaDB server has been started.

2. Check if the MariaDB server was correctly configured and uses the right socket file:

   mysqld --help --verbose | grep socket

   If the socket is different and cannot be changed, you can specify the socket in your connection parameters.

   connection = mariadb.connect(unix_socket="/path_socket/mysql.sock", ....)

   Another option is setting the environment variable MYSQL_UNIX_PORT.

   export MYSQL_UNIX_PORT=/path_to/mysql.sock

Q: Which authentication methods are supported by MariaDB Connector/Python?

MariaDB Connector/Python uses MariaDB Connector/C for client-server communication. That means all authentication plugins shipped together with MariaDB Connector/C can be used for user authentication.

General

Q: How do I execute multiple statements with cursor.execute()?

Since MariaDB Connector/Python uses binary protocol for client-server communication, this feature is not supported yet.

Q: Does MariaDB Connector/Python work with Python 2.x?

Python versions which reached their end of life are not officially supported. While MariaDB Connector/Python might still work with older Python 3.x versions, it doesn’t work with Python version 2.x.

Q: How can I see a transformed statement? Is there a mogrify() method available?

No, MariaDB Connector/Python Python uses binary protocol for client/server communication. Before a statement will be executed it will be parsed and parameter markers which are different than question marks will be replaced by question marks. Afterwards the statement will be sent together with data to the server. The transformed statement can be obtained by cursor.statement attribute.

Example:

data = ("Future", 2000)
statement = """SELECT DATE_FORMAT(creation_time, '%h:%m:%s') as time, topic, amount
               FROM mytable WHERE topic=%s and id > %s"""
cursor.execute(statement, data)
print(cursor.statement)

SELECT DATE_FORMAT(creation_time, '%h:%m:%s') as time, topic, amount FROM mytable WHERE topic=? and id > ?

Please note, that there is no need to escape ‘%s’ by ‘%%s’ for the time conversion in DATE_FORMAT() function.

Q: Does MariaDB Connector/Python support paramstyle “pyformat”?

The default paramstyle (see PEP-249) is qmark (question mark) for parameter markers. For compatibility with other drivers MariaDB Connector/Python also supports (and automatically recognizes) the format and pyformat parameter styles.

Mixing different paramstyles within the same query is not supported and will raise an exception.

Transactions

Q: Previously inserted records disappeared after my program finished

Default for autocommit in MariaDB Connector/Python is off, which means every transaction must be committed. Uncommitted pending transactions are rolled back automatically when the connection is closed.

.. code-block:: python

   with mariadb.connect(**conn_params) as conn:
       with conn.cursor() as cursor:
           cursor.execute("CREATE TABLE t1 (id int, name varchar(20))")

           # insert
           data = [(1, "Andy"), (2, "George"), (3, "Betty")]
           cursor.executemany("INSERT INTO t1 VALUES (?,?)", data)

           # commit pending transactions
           connection.commit()