ob_max_read_stale_time

Description

ob_max_read_stale_time specifies the maximum latency threshold, in μs, for weak-consistency read queries.

Limitations

• Query the variable

  • Global-level operation

    In the sys tenant or a user tenant, you can execute the SHOW VARIABLES statement to query the variable at the global level or query the SYS.TENANT_VIRTUAL_GLOBAL_VARIABLE view (in Oracle mode) or information_schema.GLOBAL_VARIABLES view (in MySQL mode) for the variable at the global level.

  • Session-level operation

    In the sys tenant or a user tenant, you can execute the SHOW VARIABLES statement to query the variable at the session level or query the SYS.TENANT_VIRTUAL_SESSION_VARIABLE view (in Oracle mode) or information_schema.SESSION_VARIABLES view (in MySQL mode) for the variable at the session level.

• Modify the variable

  • Global-level operation

    • In the sys tenant, you can directly change the value of the variable at the global level.

    • In a MySQL user tenant, you must have the SUPER or ALTER SYSTEM privilege to change the value of the variable at the global level.

  • Session-level operation

    In the sys tenant or a user tenant, you can directly change the value of the variable at the session level for the current tenant.

Attributes

Considerations

When the latency threshold for weak-consistency reads is controlled at the session level, the data returned for weak-consistency read requests in the current session must fall within the specified latency threshold. However, you can set a different latency threshold for other sessions.

Examples

Set the maximum latency threshold for weak-consistency read queries to 5,000,000 μs.

• Session-level operation

  obclient> SET ob_max_read_stale_time =5000000;
  

• Global-level operation

  obclient> SET GLOBAL ob_max_read_stale_time =5000000;