Connection Settings

Updated on 2024-12-19 GMT+08:00

This section describes parameters related to the connection mode between the client and server.

max_connections

Parameter description: Specifies the maximum number of allowed parallel connections to the database. This parameter influences the concurrent processing capability of the cluster.

Type: POSTMASTER

Value range: an integer. For CNs, the ranges from 1 to 16384. For DNs, the value ranges from 1 to 262143. Because there are internal connections in the cluster, the maximum value is rarely reached. If invalid value for parameter "max_connections" is displayed in the log, you need to decrease the max_connections value for DNs.

Default value: 800 for CNs and 5000 for DNs. If the default value is greater than the maximum value supported by kernel (determined when the gs_initdb command is executed), an error message will be displayed.

Setting suggestions:

Retain the default value of this parameter on CNs. On a DN, the value of this parameter is calculated as follows:

dop_limit x 20 x 6 + 24: dop_limit indicates the number of CPUs of each DN in the cluster. It is calculated as follows: dop_limit = Number of logical CPU cores of a single server/Number of DNs of a single server.

The minimum value is 5000.

If the parameter is set to a large value, GaussDB(DWS) requires more SystemV shared memories or semaphores, which may exceed the maximum default configuration of the OS. In this case, modify the value as needed.

NOTICE:

The value of max_connections is related to max_prepared_transactions. Before setting max_connections, ensure that the value of max_prepared_transactions is greater than or equal to that of max_connections. In this way, each session has a prepared transaction in the waiting state.

sysadmin_reserved_connections

Parameter description: Specifies the minimum number of connections reserved for administrators.

Type: POSTMASTER

Value range: an integer ranging from 0 to 262143

Default value: 3

application_name

Parameter description: Specifies the name of the client program connecting to the database.

Type: USERSET

Value range: a string

Default value: gsql

connection_info

Parameter description: Specifies the database connection information, including the driver type, driver version, driver deployment path, and process owner. (This is an O&M parameter. Do not configure it by yourself.)

Type: USERSET

Value range: a string

Default value: an empty string

NOTE:
  • An empty string indicates that the driver connected to the database does not support automatic setting of the connection_info parameter or the parameter is not set by users in applications.
  • The following is an example of the concatenated value of connection_info:
    1
    {"driver_name":"ODBC","driver_version": "(GaussDB x.x.x build 39137c2d) compiled at 2022-04-01 15:43:11 commit 3629 last mr 5138 debug","driver_path":"/usr/local/lib/psqlodbcw.so","os_user":"dbadmin"}
    

    For ODBC, JDBC, and GSQL connections, driver_name, driver_version, driver_path, and os_user are displayed by default. For other interface connections, driver_name and driver_version are displayed by default. The display of driver_path and os_user is specified by users.

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