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 4 97
Using the Database
Opening the Database
Here is a summary of the acceptable environments:
• Multiple access mode 1 and access mode 5 users
• Multiple access mode 6 and access mode 2 users
• Multiple access mode 6 users and one access mode 4 user
• Multiple access mode 6 and access mode 8 users
• One access mode 3 user
• One access mode 7 user
Subsets of these environments are also allowed. For example, all users can be access mode
5, 6, or 8 users; or there could be one access mode 1 user; and so on.
If an access mode 3 or 7 user is currently accessing the database, it cannot be opened until
that user closes the database. This is true any time an attempt is made to open a database
in an access mode that is not compatible with the access modes of others using the
database.
Database Operations
This section explains in detail what occurs when a database is opened in a particular
mode. Locking is available in all modes. In the discussion that follows, brief suggestions
are given as to when locking can be used. Refer to the discussion of the locking facility
later in this chapter for more information.
• Access Mode 1. The database is opened for shared modify access. Opening in mode 1
succeeds only if all other current users of the database are using access modes 1 or 5.
All TurboIMAGE/XL procedures are available in this mode. The critical item update
(CIUPDATE) option, which can permit you to update the values of detail data set search
and sort items, is available in this mode. A program must obtain temporary exclusive
control of the data entries before calling any procedure that changes them, such as,
DBUPDATE, DBPUT, or DBDELETE. In this way, changes to the database are synchronized
and carried out properly. This exclusive control must subsequently be relinquished to
permit other access mode 1 or mode 5 users to access these entries. Acquiring and
relinquishing is referred to as locking and unlocking, respectively. These functions are
supplied by the TurboIMAGE/XL library procedures, DBLOCK and DBUNLOCK. The
locking requirements can be met by locking the affected entries, the sets containing the
entries, or the whole database.
A mode 1 (and mode 5) user who has all or part of the database locked is assured that
no concurrent user is modifying that part of the database.
It is possible to read entries in the database using calls to DBFIND and DBGET without
locking, but the calling program must provide for the possibility that another process
could be simultaneously modifying the database. This can result in an entry being
deleted from a chain which the calling program is reading.
• Access Mode 2. The database is opened for shared update access. The DBOPEN call
succeeds only if all current users of the database are using access modes 2 and 6. All
TurboIMAGE/XL procedures are available to the access mode 2 user except DBPUT and
DBDELETE which are disallowed in this mode. The critical item update (CIUPDATE)