用户级别配置参数

ALTER USER 允许您为单个用户设置用户级别配置参数。这些设置会覆盖相同参数的数据库或会话级别设置。例如，以下 ALTER USER 语句将用户 Yvonne 和 Ahmed 的 DepotOperationsForQuery 设置为 FETCHES，从而覆盖默认设置 ALL：

=> SELECT user_name, parameter_name, current_value, default_value FROM user_configuration_parameters
   WHERE user_name IN('Ahmed', 'Yvonne') AND parameter_name = 'DepotOperationsForQuery';
 user_name |     parameter_name      | current_value | default_value
-----------+-------------------------+---------------+---------------
 Ahmed     | DepotOperationsForQuery | ALL           | ALL
 Yvonne    | DepotOperationsForQuery | ALL           | ALL
(2 rows)

=> ALTER USER Ahmed SET DepotOperationsForQuery='FETCHES';
ALTER USER
=> ALTER USER Yvonne SET DepotOperationsForQuery='FETCHES';
ALTER USER

标识用户级别参数

若要标识用户级别配置参数，请查询系统表 CONFIGURATION_PARAMETERS 的 allowed_levels 列。例如，以下查询标识会影响存储库使用的用户级别参数：

n=> SELECT parameter_name, allowed_levels, default_value, current_level, current_value
    FROM configuration_parameters WHERE allowed_levels ilike '%USER%' AND parameter_name ilike '%depot%';
     parameter_name      |     allowed_levels      | default_value | current_level | current_value
-------------------------+-------------------------+---------------+---------------+---------------
 UseDepotForReads        | SESSION, USER, DATABASE | 1             | DEFAULT       | 1
 DepotOperationsForQuery | SESSION, USER, DATABASE | ALL           | DEFAULT       | ALL
 UseDepotForWrites       | SESSION, USER, DATABASE | 1             | DEFAULT       | 1
(3 rows)

查看用户参数设置

可以用以下两种方式获取用户设置：

• 查询系统表 USER_CONFIGURATION_PARAMETERS：

  => SELECT * FROM user_configuration_parameters;
   user_name |      parameter_name       | current_value | default_value
  -----------+---------------------------+---------------+---------------
   Ahmed     | DepotOperationsForQuery   | FETCHES       | ALL
   Yvonne    | DepotOperationsForQuery   | FETCHES       | ALL
   Yvonne    | LoadSourceStatisticsLimit | 512           | 256
  (3 rows)
  

• 使用 SHOW USER：

  => SHOW USER Yvonne PARAMETER ALL;
    user  |         parameter         | setting
  --------+---------------------------+---------
   Yvonne | DepotOperationsForQuery   | FETCHES
   Yvonne | LoadSourceStatisticsLimit | 512
  (2 rows)
  
  => SHOW USER ALL PARAMETER ALL;
    user  |         parameter         | setting
  --------+---------------------------+---------
   Yvonne | DepotOperationsForQuery   | FETCHES
   Yvonne | LoadSourceStatisticsLimit | 512
   Ahmed  | DepotOperationsForQuery   | FETCHES
  (3 rows)