TurboIMAGE/XL Database Management System Reference Manual (30391-90012)
Table Of Contents
- 1 Introduction
- 2 Database Structure and Protection
- 3 Defining a Database
- 4 Using the Database
- 5 TurboIMAGE/XL Library Procedures
- Using TurboIMAGE/XL Intrinsics
- DBBEGIN
- DBCLOSE
- DBCONTROL
- DBDELETE
- DBEND
- DBERROR
- DBEXPLAIN
- DBFIND
- DBGET
- DBINFO
- INTRINSIC NUMBER 402
- Syntax
- Parameters
- Discussion
- Mode 101: Item Number
- Mode 102: Item Name
- Mode 103: Items in Database
- Mode 104: Items in Data Set
- Mode 113: BTREEMODE1 and Wildcard Character
- Mode 201: Set Number
- Mode 202: Set Name
- Mode 203: Sets in Database
- Mode 204: Sets with Item
- Mode 205: Set Capacity
- Mode 206: Number of Data Set Chunks
- Mode 207: Size of Data Set Chunks
- Mode 208: Primary and Actual Capacity
- Mode 209: B-Tree Attachment
- Mode 301: Paths
- Mode 302: Key or Search Item
- Mode 401: Logging
- Mode 402: ILR
- Mode 403: Dynamic Roll-Back
- Mode 404: Logging Subsystem Information
- Mode 406: Database Information
- Mode 501: Subsystem Access
- Mode 502: Critical Item Update
- Modes 8nn: Third-Party Indexing
- Mode 901: Language
- DBLOCK
- DBMEMO
- DBOPEN
- DBPUT
- DBUNLOCK
- DBUPDATE
- DBXBEGIN
- DBXEND
- DBXUNDO
- 6 Host Language Access
- Model Program
- ORDERS Database Model Program
- Main Body of Program
- Opening the Database
- Retrieving All the Records on a Chain (with Item Level Locking)
- Retrieving a Data Entry Using a Record Number
- Retrieving Master Data Using a Key Value
- Retrieving Data Serially (with Set Level Locking)
- Adding an Entry
- Updating an Entry
- Deleting an Entry
- Rewinding a Data Set
- Obtaining Database Information
- Obtaining Error Messages and Explanations
- Closing the Database
- C
- COBOL II
- Defining Data Types, Variables, and Intrinsics
- Main Body of Program
- Opening the Database
- Retrieving All the Records on a Chain (with Item Level Locking)
- Retrieving a Data Entry Using a Record Number
- Retrieving Master Data Using a Key Value
- Retrieving Data Serially (with Set Level Locking)
- Adding an Entry
- Updating an Entry
- Deleting an Entry
- Rewinding a Data Set
- Obtaining Database Information
- Obtaining Error Messages and Explanations
- Closing the Database
- FORTRAN 77
- Pascal
- RPG
- 7 Logging and Recovery
- Database Utilities Used in Logging and Recovery
- Recovery Options
- Logical Transactions
- Dynamic Roll-Back Recovery
- Intrinsic Level Recovery
- Logging Preparation
- Step 1--Checking MPE/iX Logging Configuration
- Step 2--Acquiring Logging Capability
- Step 3--Logging to Tape or Disk
- Step 4--Building a Log File for Logging to Disk
- Step 5--Creating the Log Identifier
- Step 6--Setting the Log Identifier
- Step 7--Setting Flags for the Database Backup Copy
- Step 8--Making a Database Backup Copy
- TurboSTORE/iX 7x24 True-Online Backup
- Logging Status
- Logging Maintenance
- Roll-Forward Recovery
- Roll-Back Recovery
- DBRECOV Commands Used with Roll-Forward and Roll-Back Recovery
- Recovery Tables
- Post-Recovery Options
- The Mirror Database
- 8 Using the Database Utilities
- Restructuring the Database with TurboIMAGE/XL Utilities
- Summary of Utility Routines
- Utility Program Operation
- DBLOAD
- DBRECOV
- >CONTROL
- >EXIT
- >FILE
- >RECOVER
- >ROLLBACK
- >RUN
- DBRESTOR
- DBSTORE
- DBUNLOAD
- DBUTIL
- >>ACTIVATE
- >>ADDINDEX
- >>CREATE
- >>DEACTIVATE
- >>DETACH
- >>DISABLE
- >>DROPINDEX
- >>ENABLE
- >>ERASE
- >>EXIT
- >>HELP
- >>MOVE
- >>PURGE
- >>REBUILDINDEX
- >>REDO
- >>RELEASE
- >>SECURE
- >>SET
- >>SHOW
- Syntax
- Parameters
- Example (Show Users)
- Example Discussion
- Example (Show All)
- Example Discussion
- Example (Show Capacity)
- Format of Show Device List
- Example (Show Device)
- Format of Show Indices
- Example (Show Indices)
- Format of Show Locks List
- Example 1 (Show Locks)
- Example 1 Discussion
- Example 2 (Show Locks)
- Example 2 Discussion
- >>VERIFY
- 9 Using a Remote Database
- 10 Internal Structures and Techniques
- 11 B-Tree Indices
- A Error Messages
- B Results of Multiple Access
- C Database Design Considerations
- D Multiple Calls to DBLOCK
- E TurboIMAGE/XL Log Record Formats
- F MPE/iX Log Record Formats
- G Recovery and Logging Quick Reference
- H TurboIMAGE/XL versus TurboIMAGE/V
150 Chapter5
TurboIMAGE/XL Library Procedures
DBCONTROL
Discussion
DBCONTROL can be called by a program for the following purposes:
• To enable or disable the AUTODEFER option for the current mode 3 DBOPEN.
• To enable or disable the critical item update option for the current process accessing the
database in mode 1, 3, or 4 depending on the CIUPDATE setting for the database.
• To enable or disable the HWMPUT for the current DBOPEN.
• To include a database in dynamic multiple database transaction.
• To activate deadlock detection for the database.
• To perform B-Tree index related tasks.
In TurboIMAGE/XL default mode, MPE/iX Transaction Management (XM) is used to log
database modifications (DBPUTs, DBDELETEs, DBUPDATEs) to the XM log file. With deferred
output, MPE/iX Transaction Management is not used. Instead, the MPE/iX file system
default mode is used. This mode keeps data pages in memory for as long as possible, either
until file close time or until no more memory is available.
Thus, with deferred output, database modifications caused by calls to DBPUT, DBUPDATE,
or DBDELETE cannot be written to the disk (or can only be partially written). Although
TurboIMAGE/XL generally operates more efficiently in this mode, a system failure while
the database is operating in this mode has a very high probability of causing internal
structural damage to the database.
A program that opens the database exclusively can call DBCONTROL mode 1 to enter the
deferred mode of operation, except when a dynamic transaction is active. In this case, all
database modifications will be kept in memory for as long as possible, either until the
database is closed or until no more memory is available.
A program that opens the database exclusively can call DBCONTROL mode 2 to turn off the
deferred mode of operation. In this case, all database modifications will be written to the
MPE/iX Transaction Management log file until the database is closed.
Programs that are designed to modify the values of detail data set search and sort items
can call DBCONTROL mode 5 if the CIUPDATE setting for a database equals ALLOWED. The
CIUPDATE option is available only in database access modes 1, 3, and 4. The mode 5 call
enables CIUPDATE for only this process until either a DBCONTROL mode 6 call disables the
option for the process or the database is closed. Other processes operating on the same
database are not impacted by these calls.
A program, which must ensure that the values of detail data set search and sort items
remain unchanged for the duration or a portion of the process, can call DBCONTROL mode 6
to disable CIUPDATE if this option has been set to ON for the database, or if the option is
ALLOWED (default or set by DBUTIL) and an earlier call to DBCONTROL mode 5 enabled the
option. CIUPDATE is available only in database access modes 1, 3, and 4. When DBCONTROL
mode 6 is used to disable CIUPDATE, the option is disabled for that process alone until a call
to DBCONTROL mode 5 enables the option for the process or the database is closed. Other
processes operating on the same database are not affected by these calls.