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

TIMEOUT
Transaction control and lockingCategory
Specifies the time in hundredths of seconds allowed to complete access requests from DML
operations for rows locked by other transactions. If the time elapses before the system can
grant a request to access or lock the data, the DML statement fails, and an error is returned.
Description
The time in hundredths of seconds to wait for a lock before
returning an error.
-1 through 2147483519
Directs the system not to time out.‘-1’
Directs the system not to wait for a lock. If the lock cannot be
acquired, an error is returned immediately.
‘0’
The default value is ‘6000’ in hundredths of seconds, which is equivalent to 60 seconds.
Values
See the Neoview SQL Reference Manual, Introduction chapter, sections on Database Integrity
and Locking and Transaction Management.
The default of a minute may be too long for BI queries in which the query is supposed to
complete within seconds. So you should evaluate this timeout and set it appropriately for
the workload at the query level or at the service level.
Usage
Not applicableProduction usage
An inappropriate TIMEOUT setting can result in long waits for users on queries while
long-running updates are running simultaneous against tables being accessed. Too short
a TIMEOUT setting can result in more queries timing out than would be the case if the
query would just wait slightly longer. So the TIMEOUT setting needs to be set appropriate
to how and when updates (including loads) are done. For example, in relation to the queries
running against that data that may be waiting on locks.
Impact
The default could be changed at the system level so that the wait time is less (or more) than
the default.
You could also consider setting this default at the service level depending on the expected
response times of the queries at that service level and the expected concurrency issues.
You can set this at the query level as well, but that would be an exception, rather than the
rule.
Level
If you issue a CONTROL TABLE statement for the TABLELOCK or TIMEOUT option, the
specified control table value overrides the system-defined default setting.
The IF_LOCKED setting of WAIT ties into the timeout being set in this CQD.
Conflicts/Synergies
The system default is a minute and that may not be a problem. But if you have concurrency
issues and you don't want users to be waiting a minute to find out that they can't access
their data due to locks, then this is the way to address that issue.
Addressing the real
problem
Neoview Release 1.0Introduced in release
Not applicableDeprecated in release
TIMEOUT 53