MySQL Shell 8.4
You can use functions available in JavaScript and Python mode to create multiple session objects of your chosen types and assign them to variables. These session objects let you establish and manage concurrent connections to work with multiple MySQL Server instances, or with the same instance in multiple ways, from a single MySQL Shell instance.
Functions to create session objects are available in the
mysqlx
and mysql
JavaScript and Python modules. These modules must be imported
before use, which is done automatically when MySQL Shell is
used in interactive mode. The function
mysqlx.getSession()
opens an X Protocol
connection to a MySQL Server instance using the specified
connection data, and returns a Session
object
to represent the connection. The functions
mysql.getClassicSession()
and
mysql.getSession()
open a classic MySQL protocol
connection to a MySQL Server instance using the specified
connection data, and return a ClassicSession
object to represent the connection. With these functions, the
connection protocol that MySQL Shell uses is built into the
function rather than being selected using a separate option, so
you must choose the appropriate function to match the correct
protocol for the port.
MySQL Shell provides the openSession()
method in the shell
global object, which can
be used in either JavaScript or Python mode.
shell.openSession()
works with both
X Protocol and classic MySQL protocol. You specify the connection
protocol as part of the connection data, or let MySQL Shell
automatically detect it based on your other connection
parameters (such as the default port number for the protocol).
The connection data for all these functions can be specified as
a URI-like connection string, or as a dictionary of key-value
pairs. You can access the returned session object using the
variable to which you assign it. This example shows how to open
a classic MySQL protocol connection using the
mysql.getClassicSession()
function, which
returns a ClassicSession
object to represent
the connection:
mysql-js>var s1 = mysql.getClassicSession('
mysql-js>user
@localhost:3306', 'password
');s1
<ClassicSession:user
@localhost:3306>
This example shows how to use
shell.openSession()
in Python mode to open an
X Protocol connection with compression required for the
connection. A Session
object is returned:
mysql-py>s2 = shell.open_session('mysqlx://
mysql-py>user
@localhost:33060?compression=required', 'password
')s2
<Session:user
@localhost:33060>
Session objects that you create in JavaScript mode using these
functions can only be used in JavaScript mode, and the same
happens if the session object is created in Python mode. You
cannot create multiple session objects in SQL mode. Although you
can only reference session objects using their assigned
variables in the mode where you created them, you can use the
shell.setSession()
method in any mode to set
as the session
global object a session object
that you have created and assigned to a variable. For example:
mysql-js>var s3 = mysqlx.getSession('
mysql-js>user
@localhost:33060', 'password
');s3
<Session:user
@localhost:33060> mysql-js>shell.setSession(s3);
<Session:user
@localhost:33060> mysql-js>session
<Session:user
@localhost:33060> mysql-js>shell.status();
shell.status() MySQL Shell version 8.1.0-commercial Connection Id: 9 Current schema: Current user: root@localhost SSL: Cipher in use: TLS_AES_256_GCM_SHA384 TLSv1.3 Using delimiter: ; Server version: 8.1.0-commercial MySQL Enterprise Server - Commercial Protocol version: Classic 10 Client library: 8.1.0 Connection: localhost via TCP/IP TCP port: 3306 Server characterset: utf8mb4 Schema characterset: utf8mb4 Client characterset: utf8mb4 Conn. characterset: utf8mb4 Result characterset: utf8mb4 Compression: Disabled Uptime: 9 hours 42 min 5.0000 sec Threads: 2 Questions: 61 Slow queries: 0 Opens: 176 Flush tables: 3 Open tables: 95 Queries per second avg: 0.001
The session object s3
is now available using
the session
global object, so the X Protocol
connection it represents can be accessed from any of
MySQL Shell's modes: SQL mode, JavaScript mode, and Python
mode. Details of this connection can also now be displayed using
the shell.status()
method, which only
displays the details for the connection represented by the
session
global object. If the MySQL Shell
instance has one or more open connections but none of them are
set as the session
global object, the
shell.status()
method returns “Not
Connected”.
A session object that you set using
shell.setSession()
replaces any existing
session object that was set as the session
global object. If the replaced session object was originally
created and assigned to a variable using one of the
mysqlx
or mysql
functions
or shell.openSession()
, it still exists and
its connection remains open. You can continue to use this
connection in the MySQL Shell mode where it was originally
created, and you can make it into the session
global object again at any time using
shell.setSession()
. If the replaced session
object was created with the shell.connect()
method and assigned to a variable, the same is true. If the
replaced session object was created while starting MySQL Shell,
or using the \connect
command, or using the
shell.connect()
method but without assigning
it to a variable, its connection is closed, and you must
recreate the session object if you want to use it again.