Operation without collecting a database update log

HiRDB acquires a history of database updates (the database update log in the system log) by UAPs (or utilities^*). This information is collected into system log files. Acquisition of database update log information can also be disabled; the advantage of doing so is that processing time, and consequently, execution time, for the UAP (or utility) is reduced.

^* The following utility programs can be used:

Database load utility (pdload)
Database reorganization utility (pdrorg)
Rebalancing utility (pdrbal)

Organization of this section: (1) Acquiring a database update log; (2) Specifying the database update log acquisition mode; (3) Notes on the RECOVERY operand; (4) Differences in operating method depending on database update log acquisition mode; (5) Notes on backup (important)

(1) Acquiring a database update log

There are three modes for collecting the database update log that is used during execution of a UAP (or a utility), as shown in Table 6-12.

Table 6-12 Database update log acquisition modes

Database update log acquisition mode	Explanation
Log acquisition mode	Acquires the database log needed for rollback or roll-forward. Normally, the log acquisition mode is used.
Pre-update log acquisition mode	Acquires only the database update log necessary for a rollback.
No-log mode	Does not acquire a database update log.

(2) Specifying the database update log acquisition mode

Table 6-13 shows the methods for specifying the database update log acquisition mode.

Table 6-13 Methods of specifying the database update log acquisition mode

Database update log acquisition mode specification method	Explanation
UAP	The database update log acquisition method is specified in the PDDBLOG operand of the client environment definition. You can specify in the PDDBLOG operand either the log acquisition mode or the no-log mode; the pre-update log acquisition mode cannot be specified.
Database load utility (pdload)	The database update log acquisition method is specified in the -l option of the database load utility (pdload).
Database reorganization utility (pdrorg)	The database update log acquisition method is specified in the -l option of the database reorganization utility (pdrorg).
Rebalancing utility (pdrbal)	The database update log acquisition method is specified in the -l option of the rebalancing utility (pdrbal).
Using a user LOB RDAREA	In the case of data stored in a user LOB RDAREA, the database update log acquisition method is specified in the RECOVERY operand of CREATE TABLE. If abstract data type data is stored in the LOB RDAREA, the pre-update log acquisition mode cannot be specified (it is ignored if specified).

(3) Notes on the RECOVERY operand

The database update log acquisition method specified in the RECOVERY operand is subject to change when either the PDDBLOG operand or the -l option is specified. Table 6-14 shows the relationship between the specification value in the RECOVERY operand and the PDDBLOG operand or the -l option, on the one hand, and the value that is assumed during execution of the UAP (or the utility), on the other hand.

Table 6-14 Relationship between the specification value in the RECOVERY operand and PDDBLOG operand or the -l option, and the value that is assumed during execution of the UAP (or the utility)

Specification of PDDBLOG operand or -l option	Specification of RECOVERY operand
Specification of PDDBLOG operand or -l option	ALL	PARTIAL	NO
ALL a (log acquisition mode)	ALL	PARTIAL	NO
PARTIAL p (pre-update log acquisition mode)	PARTIAL	PARTIAL	NO
NO n (no-log mode)	NO	NO	NO

ALL or a: log acquisition mode

PARTIAL or p: pre-update log acquisition mode

NO or n: no-log mode

(4) Differences in operating method depending on database update log acquisition mode

The different database update log acquisition modes can result in differences in the operating methods in the following two areas:

Processing performed by HiRDB and action to be taken by the user in the event of abnormal termination of the UAP
Timing for database recovery

(a) Processing performed by HiRDB and the action to be taken by the user in the event of abnormal termination of the UAP

Table 6-15 shows the processing performed by HiRDB and the action to be taken by the user in the event of abnormal termination of the UAP.

Table 6-15 Processing performed by HiRDB and the action to be taken by the user in the event of abnormal termination of the UAP

Database update log acquisition mode	HiRDB processing	User action
Log acquisition mode	Rolls back an updated RDAREA to its status before the UAP executed or to the last synchronization point set before the abnormal termination.	If the RDAREA is rolled back to its status before the UAP was executed, re-execute the UAP. If the RDAREA is rolled back to the last synchronization point that was set before the abnormal termination, execute the processing following the synchronization point.
Pre-update log acquisition mode
No-log mode	Does not perform roll back. Error shutdown (logless shutdown) is performed on the updated RDAREA. The contents of the RDAREA are destroyed.	Using as input information a backup that was made before execution of the UAP, execute the database recovery utility (pdrstr) to recover the RDAREA, and then re-execute the UAP.

(b) Timing at which database can be recovered

Table 6-16 shows the times at which the database can be recovered by the database recovery utility (pdrstr).

Table 6-16 Times for recovering the database

Database update log acquisition more	Time for database recovery
Log acquisition mode	Either the backup acquisition point or any synchronization point subsequent to the backup acquisition point
Pre-update log acquisition mode	Backup acquisition point
No-log mode	Backup acquisition point