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
Chapter 7 355
Logging and Recovery
Roll-Back Recovery
When transaction T4 is aborted, TurboIMAGE/XL completes the transaction by issuing an
abnormal end (DBABEND). This transaction is then seen as completed by the roll-back
feature and is not normally rolled back. If the aborted transaction is also to be rolled back,
the following DBRECOV command must be issued before issuing the DBRECOV >RUN
command (refer to the discussion of DBRECOV in chapter 8):
>CONTROL NOABORTS
The above command string causes the aborted transaction to be treated as an incomplete
transaction during roll-back recovery. When
>CONTROL NOABORTS
is used, recovery must be
performed at system startup time before anyone modifies the database. Refer to "Record
Numbers" under the DBRECOV >CONTROL discussion in chapter 8 for considerations when
using the >CONTROL command.
Enabling the Roll-Back Feature
To enable the roll-back feature complete the following sequence:
1. Set the logid and build a log file (if logging to disk) as shown in steps 2 through 6 of
"Logging Preparation" earlier in this chapter.
2. For each particular database, disable access and enable the roll-back and recovery
features by entering the following DBUTIL commands. You can also enable the
MUSTRECOVER option if you wish to use it.
>>DISABLE
database name
FOR ACCESS
>>ENABLE
database name
FOR ROLLBACK,RECOVERY
>>ENABLE
database name
FOR MUSTRECOVER
Enable any other appropriate flags as discussed in step 7 under "Logging Preparation."
If the logid was not set and/or the log file was not built before the >>ENABLE command is
issued for roll-back recovery, a warning message that the logid or the log file is
non-existent is displayed on the screen. Enable any other appropriate flags as discussed
in step 7 under "Logging Preparation." Enabling for roll-back or MUSTRECOVER
automatically enables the database for logging.
3. Make a backup copy of the database as discussed in step 8 under "Logging
Preparation." You may use DBSTORE or TurboSTORE/iX 7x24 True-Online Backup
(with ONLINE=START or ONLINE=END option) regardless of the database being
open or closed with roll-back recovery.
4. Start the logging process and enable user access to the appropriate databases as shown
in "Logging Maintenance," earlier in this chapter. After the logid has been set and the
log file built, DBUTIL automatically enables logging when roll-back is enabled. Note
that ILR is not needed for roll-back recovery; however, if ILR is enabled together with
roll-back recovery, logging and ILR must be disabled separately.
When roll-back recovery is enabled, DBUTIL sets a roll-back flag in the root file to indicate
that roll-back recovery is enabled for the database. DBUTIL also reserves six words in the
root file for the roll-back time stamp (three words for the previous time stamp and three