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==================
Connection pooling
==================
A connection pool is a cache of connections to a database server where connections can be reused for future requests.
Since establishing a connection is resource-expensive and time-consuming, especially when used inside a middle tier
environment which maintains multiple connections and requires connections to be immediately available on the fly.
Especially for server-side web applications, a connection pool is the standard way to maintain a pool of database connections
which are reused across requests.
---------------------------------------
Configuring and using a connection pool
---------------------------------------
The typical way for creating and using a connection pool is
1. Create (and configure) a connection pool
2. Obtain a connection from connection pool
3. Perform database operation(s)
4. Close the connection instance and return it to the connection pool.
^^^^^^^^^^^^^^^^^^^^^^^^^^
Creating a connection pool
^^^^^^^^^^^^^^^^^^^^^^^^^^
When creating a connection pool, the following parameters have to be provided:
1. Connection pool specific parameters
- **`pool_name`**: The name of the pool, if not specified |MCP| will raise an exception.
- **`pool_size`**: The size of the pool, if not specified a default of 5 will be set.
- **`pool_reset_session`**: If set to True, the connection will be reset before returned to the pool
- **`pool_invalidation_interval`**: specifies the validation interval in milliseconds after which the status of a connection requested from the pool is checked. The default values is 500 milliseconds, a value of 0 means that the status will always be checked. Since 1.1.0
2. Connection parameters
- In addition to the connection pool specific parameters initialization method of ConnectionPool Class accepts the same parameters as the connect() method of mariadb module.
*Example*:
.. testcode::
import mariadb
# connection parameters
conn_params= {
"user" : "example_user",
"password" : "GHbe_Su3B8",
"database" : "test"
}
# create new pool
with mariadb.ConnectionPool(pool_name="myfirstpool", pool_size=5, **conn_params) as pool:
print("Pool size of '%s': %s" % (pool.pool_name, pool.pool_size))
# get a connection from pool
with pool.get_connection() as conn:
# print the default database for connection
print("Current database: %s" % conn.database)
*Output*:
.. testoutput::
Pool size of 'myfirstpool': 5
Current database: test
{% @marketo/form formId=\"4316\" %}
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