Help Center/ GaussDB(DWS)/ More Documents/ Developer Guide (ME-Abu Dhabi Region)/ GUC Parameters/ Connection and Authentication/ Connection Settings
Updated on 2022-06-11 GMT+08:00
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Connection Settings

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 the CN. Set this parameter on the DN to the following calculation result: Number of CNs x Value of this parameter on the CN.

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.

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

  • 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 8.1.1 build af002019) compiled at 2020-01-10 05:43:20 commit 6995 last mr 11566 debug","driver_path":"/usr/local/lib/psqlodbcw.so","os_user":"omm"}

    driver_name and driver_version are displayed by default. Whether driver_path and os_user are displayed is determined by users.