Main storage database: MSDB

Use MSDBs to store the most frequently-accessed data. MSDBs are suitable for applications such as general ledger applications in the banking industry.

Recommendation: Use DEDBs instead of MSDBs when you develop new Fast Path databases. Terminal-related MSDBs and non-terminal-related MSDBs with terminal-related keys are no longer supported. Although non-terminal-related MSDBs with non-terminal-related-keys are still supported, you should consider converting any existing MSDBs to DEDBs. You can use the MSDB-to-DEDB Conversion utility.

MSDB characteristics

MSDBs reside in virtual storage, enabling application programs to avoid the I/O activity that is required to access them. The two kinds of MSDBs are terminal-related and non-terminal-related.

In a terminal-related MSDB, each segment is owned by one terminal, and each terminal owns only one segment. One use for this type of MSDB is an application in which each segment contains data associated with a logical terminal. In this type of application, the program can read the data (perhaps for reporting purposes), but cannot update it. A non-terminal-related MSDB stores data that is needed by many users during the same time period. It can be updated and read from all terminals (for example, a real time inventory control application, where reduction of inventory can be noted from many cash registers).

An overview of how MSDBs work

This topic contains Diagnosis, Modification, and Tuning information.

MSDB segments are stored as root segments only. Only one type of pointer, the forward chain pointer, is used. This pointer connects the segment records in the database.