Theoretically better than PHP persistent connections, since ODBC itself takes care of resetting the connections back to a "ground" state. Connection pooling defaults to ON, since this is generally useful. You can turn it off by using: pdo_odbc.connection_pooling=off in your php.ini file. You may configure how ODBC matches connection details to existing connections by setting this value to "strict" (the default) or "relaxed". You are encouraged to read the ODBC specs before changing this value.