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
Appendix H 685
TurboIMAGE/XL versus TurboIMAGE/V
Intrinsic Level Recovery
Intrinsic Level Recovery
Intrinsic Level Recovery (ILR) is not required to protect the structural integrity of the
database, because in default recovery mode TurboIMAGE/XL takes advantage of an
internal MPE/iX file system service, called Transaction Management (XM), to provide
intrinsic level backup and recovery. Unless AUTODEFER is enabled, all intrinsics that
modify the database (DBPUTs, DBDELETEs, and DBUPDATEs) are written to XM log file pages
by MPE/iX. In default recovery mode, XM log file pages are only written to disk when one
of the following occurs:
• A system-specified time has elapsed.
• A request is made by a subsystem, such as TurboIMAGE/XL, to flush the XM log file to
disk (for example, ILR is enabled, or DBEND mode 2 is specified and logging is enabled).
• The XM buffer is full.
Thus, intrinsics that have completed may not yet be written to disk. If a system failure
occurs, only intrinsics that have been written to disk are recovered.
When recovery is
necessary, it must be performed at system startup time before anyone
modifies the database.
ILR also uses the MPE/iX Transaction Management service. When ILR is enabled, XM log
file pages are written to disk at the end of each completed DBDELETE and DBPUT. If a system
failure occurs, at most only one DBPUT or DBDELETE is not recovered. (Note that a completed
DBUPDATE does not force a XM log write to disk.) Because of these differences in
implementation, ILR on TurboIMAGE/V is not completely compatible with ILR on
TurboIMAGE/XL.
ILR does have performance implications. Therefore, you may wish to reevaluate your use
of ILR with TurboIMAGE/XL. ILR is no longer necessary to ensure the structural integrity
of the database. However, if your data is not easily recoverable (information taken over the
telephone, for example) you may wish to use ILR because at most only one intrinsic can be
lost.
NOTE
Before moving TurboIMAGE/V databases to MPE/iX, it is recommended that
ILR be disabled. If it is not, TurboIMAGE/XL assumes you want ILR to
remain enabled.
Major Differences
• ILR is performed by MPE/iX Transaction Management. As a result, the ILR file
DatabaseName00 does not exist. All transactions are logged to the MPE/iX Transaction
Management log file.
• ILR is not required to protect the structural integrity of the database.
• ILR is not required for roll-back recovery.
• DBUPDATE is included with DBPUT and DBDELETE in Intrinsic Level Recovery. However,
completed DBUPDATEs are not guaranteed to be committed to the log file for recovery.