Neoview Control Query Default (CQD) Reference Guide (R2.5)

‘ON’
‘OFF’
The default value is ‘OFF’.
Values
This setting provides a realistic measure of the query's performance, minus the cost/time
of returning the rows to the client. It is especially useful for testing the plans and
performance of queries that return large result sets.
Usage
Only use this CQD to assess the performance of a query.Production usage
The query runs completely but no rows are returned.Impact
QueryLevel
Not to be confused with SELECT [LAST 0] which behaves the same way but does not
guarantee that the plan is the same as when you do not use the [LAST 0] clause in the query.
Conflicts/Synergies
Not applicableAddressing the real
problem
Neoview Release 1.0Introduced in release
Not applicableDeprecated in release
QUERY_LIMIT_SQL_PROCESS_CPU
Runtime controlsCategory
Use to limit the amount of CPU time that a query is allowed to use in any one server process
(MXESP) including the NDCS server (MXOSRVR). From R2.5 the limit also includes the
CPU time the query spends in the disk process (ESAM).
If a query exceeds the limit, an error is raised and the query is terminated. This is a way to
limit the impact on the system of a poorly written or badly optimized query.
Description
There is no limit.‘0’
The limit, in seconds, to how much CPU time a query is allowed
to use.
greater than ‘0’ and up
through ‘2,147,483,583’
The default value is ‘0’.
Values
This setting helps customers with queries that are poorly written or are badly optimized.
A poorly written query does not use predicates to limit the number of rows processed. A
query that joins large tables without a predicate can have a severe impact on the system.
A badly optimized query can result from failure to maintain histograms. Typically, these
are ad-hoc queries.
These types of queries seldom run to completion, and are instead stopped after the problems
that they cause to other users of the system are noticed.
Usage
Not applicableProduction usage
Use of this default can prevent any one query from using an unlimited amount of CPU
time. However, if the default is set too low, then even well behaved, useful queries fail to
complete.
Impact
ServiceLevel
Not applicableConflicts/Synergies
Use standard processed for creating high-quality queries, and procedures that ensure that
table histograms are always current.
Addressing the real
problem
Neoview Release 2.4Introduced in release
Not applicableDeprecated in release
60 Miscellaneous