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LOGSCAN scan range definition

This syntax determines the part of the DB2 log that Log Master scans for log records. It also enables you to specify the start point for REDO information (often called a recovery point).

The following figure shows the Scan range definition syntax of the LOGSCAN statement.

If you specify the REPOS DELETE keyword of the LOGSCAN statement, the Scan range definition is not required.

Scan range definition syntax diagram

OptionDescription
FROM Range definition TO Range definition

Specifies the portion of the DB2 log that Log Master scans (also called the time frame). FROM indicates the start point and TO indicates the end point of the log scan. Each Range definition defines one point in the DB2 log. For more information, see Range definition.

OR LIMIT

Defines an alternate limit on the range of the log scan. When you specify this keyword, the end point of your log scan is the point defined by the TO keyword in the Range Definition or the point defined by OR LIMIT, whichever comes first. The default value of this keyword does not define an alternate limit.

This keyword is frequently used with ongoing jobs. For example, assume that during a period of high logging activity, an ongoing job does not complete during its assigned processing window. The operating system terminates the job. No valid output is produced. If you run the job again, the same problem exists. In this situation, define an alternate limit that includes a range of log short enough to be processed by Log Master during the window. You can then run the same job repeatedly (producing valid output for each run without changing SYSIN syntax for each run), until you work your way through the period of high activity and 'catch up' to normal operation.

Note

The limit defined by this keyword does not define how long Log Master executes at runtime; it defines only how much log Log Master scans. For example, if you specify OR LIMIT 01:00:00, Log Master does not stop running after 1 hour; it stops after it has scanned all log files covering a 1-hour period from your start point. The same principle applies to a limit specified as a number of log files.

ValueDescription
nnn LOG FILES Defines the alternate limit as a number of log files. Log Master determines which log file contains the start point specified by the FROM keyword of the Range Definition, adds the specified number of log files, and sets the alternate limit equal to the end point of the selected log file. In a data sharing environment, Log Master performs the same process to determine the end points of the selected log files on each member, and then sets the alternate limit equal to the earliest end point.
nnn DAYS

Defines the alternate limit as a number of days. Specify this keyword either by itself or with a hh:mm:ss value that is added to the number of days. Log Master determines the date and time of the start point specified in the Range Definition, adds the specified number of days, and sets the alternate limit equal to the computed date and time value.

Log Master computes the date and time based on your specified start point. When all of the following conditions exist, Log Master adjusts the start point before it computes the alternate limit:

  • Log Master runs in a non-data-sharing environment.

  • The start point in the Range Definition is not specified as a date and time value.

  • The current log scan is either a non-ongoing log scan or the initial run of an ongoing log scan.

In this situation, Log Master sets the start point equal to the starting timestamp value of the log file that contains your specified start point.

hh:mm:ss

Defines the alternate limit as a number of hours, minutes, or seconds. Specify this value either after the DAYS keyword, or by itself. Log Master determines the date and time of the start point specified in the Range Definition, adds the specified period of time, and sets the alternate limit equal to the computed date and time value.

To specify a period less than one hour, specify the hours value as 00. To specify a period of seconds, specify both the hours and minutes value as 00.

Be aware of the following points when specifying an alternate limit:

  • If you specify the RERUN RUNSEQ keyword to execute a previous log scan again, Log Master ignores the specified OR LIMIT when processing a rerun. If you specify USE RUNSEQ to use the start point of a previous log scan, be sure that the end point defined by OR LIMIT is after the end point of the previous log scan.

  • The implementation of OR LIMIT depends on Repository changes introduced in Log Master version 7.3.00. Do not specify OR LIMIT for the first execution of a migrated work ID after you install a later version of Log Master than 7.3.00 if that work ID was migrated from an earlier version than 7.3.00, and it contains an ongoing log scan. Subsequent executions can support an OR LIMIT specification.

REDO FROM

Determines the start point that Log Master uses to generate REDO information. This point is also referred to as the recovery point or point of recovery. Log Master can write REDO information to a logical log file, an SQL output file (in the form of REDO SQL), or a report (in one of three report formats).

Use REDO information to re-apply a set of transactions after a recovery action, while omitting a set of 'problem' transactions defined by your Range definition and WHERE clause. For more information, see REDO.

To generate REDO information, define a recovery point and a WHERE clause that refers to at least one specific DB2 object (such as a table space, table, or column). BMC Software strongly recommends that you generate REDO SQL before you recover any table spaces. You might be able to generate the SQL statements after the recovery by using the PROCESS PITS keyword of the OPTION statement, but BMC Software does not recommend doing so. For more information, see PROCESS PITS.

ValueDescription
LASTQUIESCEDirects Log Master to generate REDO information starting with the most recent quiesce point available in the SYSIBM.SYSCOPY table of the DB2 Catalog. The quiesce point must include all table spaces explicitly or implicitly specified in the WHERE clause or filter. You cannot specify this type of recovery point if the value of the FILTER METHOD keyword (or the FLTRMTHD installation option) is DYNAMIC.
RBA | LRSN X 'byteString'Directs Log Master to generate REDO information starting with a specific RBA/LRSN. The byte string can be up to 12 characters long. For extended RBAs/LRSNs, it can be up to 20 characters long. Use the following format: RBA X'nnnnnnnnnnnn'.
MARK logMarkName

Directs Log Master to generate REDO information starting at the log mark represented by logMarkName. A log mark is a symbolic name that represents a given point in the log. Remember that a log mark name created within a given job step cannot be referenced within that job step.

For more information about log marks and log mark names, see MARK logMarkName.

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