HP 3000 Manuals HP 3000 Manuals
Multiple Database Transaction Logging (MDBX)
by Ron Harnar/Mark Boronkay
Commercial Systems Division/DBL
TurboIMAGE provides a transaction logging and recovery capability that
allows a programmer to group multiple TurboIMAGE intrinsic calls into
logical transactions that are treated as single units of work during
database recovery. The logging and recovery capability is currently
limited to transactions involving a single database. This may pose
problems for complex applications with units of work that span multiple
databases. To address this specialized requirement, TurboIMAGE will
provide a multiple-database transaction capability (MDBX).
NEW TURBOIMAGE FEATURES TO SUPPORT MDBX
The following changes have been made to TurboIMAGE in order to support
MDBX:
* The TurboIMAGE intrinsics DBBEGIN and DBEND are enhanced so that
programmers can define MDBXs involving up to 15 databases.
* A new mode (404) is added to DBINFO for obtaining information
about MDBXs.
* The DBRECOV utility is modified to allow recovery of MDBXs.
* New operational requirements are enforced for applications that
use MDBX.
* The TurboIMAGE logfile is changed to permit logging of MDBXs.
Two types of MDBX are available, optimized and non- optimized.
Non-optimized MDBX makes use of DBBEGIN and DBEND records in the user
logfile. Optimized MDBX generates new logging records (MDBXBEGIN and
MDBXEND) designed to save space in the logfile.
NOTE The use of the new log records generated by the optimized version
of MDBX will prevent Silhouette from processing these entries
appropriately. It is therefore recommended that Silhouette users
use the non-optimized version of MDBX on log files that are
accessed by Silhouette.
The use of MDBX is optional. TurboIMAGE applications that are currently
using single-database transactions can continue to do so without any
coding or operational changes. The above changes apply only if the
programmer wishes to take advantage of the MDBX enhancement.
For more information regarding MDBX, please refer to the TurboIMAGE/XL
Database Management System Reference Manual (P/N 30391- 90001).