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.
