ODBC Server Installation and Management Manual

Managing NonStop ODBC Server Resources
HP NonStop ODBC Server Installation and Management Manual—429395-002
5-19
Usage Considerations
The query status table hold records temporarily while a query is running. After
statement execution finishes, the status record is deleted. The NonStop ODBC
Server deletes status records for a user session at the end of user session to
avoid monitoring obsolete data and governing a query that is no longer running.
Only if the NonStop ODBC Server terminates abnormally could there be records
left from queries no longer running. The NonStop ODBC Server always
initializes the query status table at start-up time by checking to see if records
with the same CPU and PIN exist and removes them from the table.
Usage Considerations
When the user logs on, the NonStop ODBC Server reads the user profile to find out
whether this user needs to be governed. If a governing policy exists, the NonStop
ODBC Server retrieves the policy and actions to be used later. If governing is disabled
or the policy name is omitted from the user profile, or if there is a problem retrieving the
governing policy, all queries will be executed as if there were no limit to be applied.
These configurations could be dynamically reconfigured according to the current
dynamic reconfiguration rules.
What Statements Can Be Scheduled
When the statement caching is on, query scheduling policies apply to all user-issued
SQL DML statements. When caching is not on, scheduling policies are applied to all
SELECT statements and to user-prepared INSERT, UPDATE, and DELETE statements
only. Internally, SQL statements prepared by the NonStop ODBC Server, such as
EXECUTE IMMEDIATE statement, are governed.
When Scheduling Action Takes Effect
After a statement has been compiled, the resource governing facility determines what
action to take based on the estimated cost. Action to change the priority or to prevent
the statement from running takes effect before the statement is executed. If a change
of priority is performed, the priority is restored at the end of the query to its original
value set by SCS. If an action is applied, a message is returned to the client to report
that action. As this is an informational message only, the client application could report
the message or could choose to ignore it.
If no estimated cost is specified in the governing policy, or if a particular cost range is
omitted, queries are run with the current environment setting. If for any reason the
priority cannot be changed, a warning message is written to the EMS log, but the query
continues to run.
When the Run-Time Governor Takes Effect
The resource governing facility governs query execution by recording time and I/O
consumed by the query. The facility periodically checks to see if one of the limits
specified has been exceeded. If it finds such a case, it triggers the action defined by