DBH start statements and options

The purpose of DBH start statements and options is to parametrize the DBH. They specify the resources, limit values and work rules for the current session.

Entering DBH start parameters

System administrators specify the DBH start statements in a specific sequence when starting the SESAM/SQL DBH. After the first start statement, SET-DBH-OPTIONS, they can add DBH options as necessary. The DBH reads the start statements and options from SYSDTA.

There are different ways of entering the DBH start statements and options:

• entry within the procedure used to start the DBH

• entry via a file to which system administrators assign the SYSDTA system file before starting the DBH

• entry directly at the console (in interactive mode)

• entry via the configuration file which system administrators assign via the link name SESCONF or the CONNECT-SESAM-CONFIGURATION statement.

The format of DBH start statements and options follows the same rules as SDF ( System Dialog Facility), see the “SDF Dialog Interface” manual). SDF supports the entry of DBH start statements and options directly in a guided dialog, analyzes each statement entered, and transfers it for further processing to the DBH.

DBH start statements

The DBH start statements initiate the parametrization of the DBH. They cause the DBH options to be read and entries to be added to the SQL database catalog list and the CALL DML table catalog list. DBH start statements are entered as three SDF statements:

1. SET-DBH-OPTIONS

2. ADD-SQL-DATABASE-CATALOG-LIST

3. ADD-OLD-TABLE-CATALOG-LIST

The first DBH start statement must be the SET-DBH-OPTIONS statement. The other two statements are optional because entries in the SQL database catalog list or CALL DML table catalog list can also be made using administration statements.

DBH options

DBH options parameterize the DBH and define the main characteristics of a session. The system administrator can modify most of the DBH options (with the exception of CONFIGURATION-NAME and DBH-NAME) during operation. The current DBH options can be saved in a file and used again in the next DBH session.

DBH options are subdivided into higher- and lower-level DBH options.

• Higher-level DBH options, such as ADMINISTRATION or STORAGE-SIZE, relate to a particular subject area.

• Lower-level DBH options each deal with part of the subject area of their higher-level option.

All the higher-level DBH options are assigned one or more lower-level options. System administrators enter the DBH options having entered the DBH start statement SET-DBH-OPTIONS.

There are default settings for all DBH options. The system administrators only need to enter those options for which they wish to specify values other than the defaults. However, before they can specify their own values for one or more lower-level options, they must first enter the associated higher-level option. System administrators can use administration statements (MODIFY-...) to modify many DBH options during ongoing operation.

The DBH options available to system administrators are listed in an overview on the pages that follow. For a detailed description of DBH options, see the “Database Operation” manual.

When entering DBH options via SYSDTA, ensure that the comment lines are started by “//REMARK”. The specifications “/REMARK” and “REMARK” will be interpreted as commands and this will lead to an SDF error message. Comments must not be put inside statements.

Overview of the DBH options

Higher-level option	Lower-level option	Brief description
DBH-IDENTIFICATION	CONFIGURATION-NAME DBH-NAME	Identifies the DBH Defines the configuration name Defines the DBH name
ADMINISTRATION	ACCOUNTING ADMINISTRATOR MSG-OUTPUT SECURITY	Administers the DBH Activates accounting Assigns administration authorization Controls the outputs of the DBH Prevents unauthorized access
CPU-RESOURCES	DBH-TASKS SERVICE-TASKS	Controls the CPU utilization Specifies the number of the DBH tasks Specifies the number of tasks for service requests
FILE-RESOURCES	MEDIA-CATALOG SESSION-LOGGING-ID	Specifies settings for files Creates a media catalog Identifies session-specific files
LINKED-IN- ATTRIBUTES	CODED-CHARACTER-SET	Specifies attributes of the linked-in DBH Specifies a coded character set which is used by the user program.
RECOVER-OPTIONS	SYSTEM-DATA-BUFFER USER-DATA-BUFFER MEDIA-CATALOG	Specifies settings for RECOVER or REFRESH runs Dimensions the system-data buffer Dimensions the user-data buffer Creates the media catalog
STORAGE-SIZE	CURSOR-BUFFER SYSTEM-DATA-BUFFER TRANSFER-CONTAINER USER-DATA-BUFFER WORK-CONTAINER	Creates buffer and container size Dimensions the cursor buffer Dimensions the system data buffer Dimensions the transfer container Dimensions the user data buffer Dimensions the work container
SYSTEM-LIMITS	COLUMNS OLD-TABLE-CATALOG SPACES SQL-DATABASE-CATALOG SQL-SUPPORT SUBORDERS SYSTEM-THREADS THREADS USERS	Specifies limit values Enlarges the area for retrieval statements Specifies the maximum number of entries permitted in the CALL DML table catalog Specifies the maximum number of simultaneously accessible spaces Specifies the maximum number of entries permitted in the SQL database catalog Specifies limit values for the SQL interface Makes SQL scans or logical files available Specifies the number of concurrent system threads Specifies the maximum number of concurrent threads Specifies the maximum number of concurrent users
SYSTEM STRATEGIES	REQUEST-CONTROL RESTART-CONTROL RETRIEVAL-CONTROL TRANSACTION-SECURITY	Defines the processing strategy Activates priority control Controls the duration of availability in the event of a restart Influences the search strategy of the DBH Activates transaction management

Table 60: Higher- and lower-level DBH options