CREATE USER MAPPING
Function
CREATE USER MAPPING defines a new mapping from a user to a foreign server.
Precautions
If the password option is displayed, ensure that the usermapping.key.cipher and usermapping.key.rand files exist in the $GAUSSHOME/bin directory of each node in openGauss. If the two files do not exist, use the gs\_guc tool to generate them and use the gs\_ssh tool to release them to the $GAUSSHOME/bin directory on each node in openGauss.
Syntax
CREATE USER MAPPING FOR { user_name | USER | CURRENT_USER | PUBLIC }
SERVER server_name
[ OPTIONS ( option 'value' [ , ... ] ) ]
Parameter Description
user_name
Specifies the name of an existing user to map to a foreign server.
CURRENT_USER and USER match the name of the current user. When PUBLIC is specified, a public mapping is created and used when no mapping for a particular user is available.
server_name
Specifies the name of the existing server for which a user mapping will be created.
OPTIONS ( { option_name ' value ' } [, …] )
Specifies options for user mapping. These options typically define the actual username and password for this mapping. The option name must be unique. The allowed option names and values are related to the foreign data wrapper of the server.
NOTE:- User passwords are encrypted and stored in the system catalog PG_USER_MAPPING. During the encryption, usermapping.key.cipher and usermapping.key.rand are used as the encryption password file and encryption factor. Before using the tool for the first time, run the following command to create the two files, save the files to the $GAUSSHOME/bin directory on each node, and ensure that you have the read permission on the files. gs_ssh helps you quickly place files in the specified directory of each node.
gs_ssh -c "gs_guc generate -o usermapping -S default -D $GAUSSHOME/bin"- If the -S parameter is set to default, a password is randomly generated. You can also specify a password for the -S parameter to ensure the security and uniqueness of the generated password file. You do not need to save or memorize the password. For details about other parameters, see the description of the gs_guc tool in the “Tool Reference”.
Options supported by oracle_fdw are as follows:
user
Oracle server username.
password
Password of the Oracle user.
Options supported by mysql_fdw are as follows:
username
Username of the MySQL server or MariaDB.
password
User password of the MySQL server or MariaDB.
Options supported by postgres_fdw are as follows:
user
Username of the remote openGauss database.
password
User password of the remote openGauss database.
NOTE:
The password entered by the user is encrypted in the openGauss background to ensure security. The key file required for encryption must be generated using the gs_guc tool and released to the $GAUSSHOME/bin directory of each node in openGauss using the gs_ssh tool. The password cannot contain the prefix 'encryptOpt'. Otherwise, it is considered as encrypted ciphertext.
Helpful Links
ALTER USER MAPPING and DROP USER MAPPING