11.3.4 option statement (specification of optional information)

The option statement specifies pdreclaim's execution monitoring time.

Criteria
Specify the option statement to monitor the execution time of pdreclaim.
Organization of this subsection
(1) Format
(2) Explanation

(1) Format

 option [exectime=pdreclaim-monitoring-time]
        [globalbuffer_lru={yes|no}]
        [io_interruption_interval=pause-interval-during-free-page-release-processing[,pause-duration]]

(2) Explanation

(a) exectime=pdreclaim-monitoring-time

~<unsigned integer> ((0-35791394))

Specifies the pdreclaim execution monitoring time in minutes.

Guideline for the specification value
The purpose of this operand is to detect a no-response error, not to monitor the execution time of a long transaction. Therefore, you should specify a sufficient time for processing the applicable table. For example, to monitor the execution time of a pdreclaim that should terminate in 7 to 8 minutes, specify exectime=20, not exectime=10.
Rules
  1. If you omit this operand or specify 0, the system will not monitor the execution time.
  2. This operand takes the precedence over the pd_utl_exec_time operand in the system definition. The table below describes the relationship between the exectime operand and the pd_utl_exec_time operand in the system definition.

    Table 11-9 Relationship between the exectime operand and the pd_utl_exec_time operand in the system definition (pdreclaim)

    exectime operand valuepd_utl_exec_time operand value in the system definition
    Omitted or 0A
    Omitted--Monitoring with value A
    0----
    BMonitoring with value BMonitoring with value B
    Legend:
    --: Execution time is not monitored.

  3. If processing does not terminate within the specified amount of time, the system terminates pdreclaim forcibly and acquires error information in order to determine the cause of the no-response. Note that the targets of this monitoring are the utility server processes for pdrorg (0mrorg) and the single server (or back-end server). In the event of an error in the command process (pdreclaim or pdrorg), pdreclaim cannot be terminated forcibly. For details about the error information that is collected, see the pd_utl_exec_time operand in the manual HiRDB Version 9 System Definition.
(b) globalbuffer_lru={yes|no}

Specifies whether the pages read into the global buffer are to be treated as the oldest pages. When the free page release utility (pdreclaim) is executed, the utility first reads the target pages into the global buffer and then performs processing. If a shortage of space occurs in the global buffer, online performance might be degraded because the pages read into the global buffer by previous applications are removed from the global buffer (LRU management method). To avoid such performance degradation, specify no in this operand. When no is specified, the pages read by the free page release utility (pdreclaim) are always treated as the oldest pages that will be removed first in the event of a shortage of space in the global buffer. When no is not specified, the LRU management method is used.

(c) io_interruption_interval=pause-interval-during-free-page-release-processing[,pause-duration]

Specify this operand to reduce I/O delays in application programs by pausing pdreclaim for a specified interval.

pause-interval-during-free-page-release-processing
~<unsigned integer>((10 to 100000))
Specifies a pause interval in terms of number of pages accessed. pdreclaim pauses each time the number of pages it has accessed per RDAREA for the target table or index reaches the specified value.
This operand is applicable only when free pages are released; it is not applicable when free segments are released.
pause-duration
~<unsigned integer>((1 to 1000))<<100>>
Specifies the duration of the pause interval (in milliseconds) when you specify pause-interval-during-free-page-release-processing. pdreclaim pauses for the specified number of milliseconds at the following times:
  • Immediately after committing
  • When the number of pages accessed using the global buffer has reached the pause interval
Guidelines for specification values
When this operand is specified, the pdreclaim command's processing time is increased. If you execute the pdreclaim command while applications are running, the applications' processing performance might be affected adversely. Therefore, we recommend that you specify this operand together with the globalbuffer_lru operand (however, if you execute the pdreclaim command after business hours, there is no need to specify both this operand and the globalbuffer_lru operand). When this operand is specified, the pdreclaim command's processing time increases by the amount of time determined from the formula shown below. Take into account the frequency of I/O operations in the application programs when you specify this operand.
(number of pages to be released#1[Figure] pause interval + number of commits#2) [Figure] pause duration (milliseconds)
#1
To obtain number of pages to be released, see Max Sum Page, which is output in the analysis results of the database condition analysis utility (pddbst).
#2
number of commits is obtained by dividing the number of pages that can be released by this utility by the commit interval specified in the -m option. To obtain the number of pages that can be released, see Collect Prearranged Page, which is output in the analysis results of the database condition analysis utility (pddbst).