OpenTP1 Version 7 Description

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4.4.4 User files: ISAM files (ISAM and ISAM/B)

ISAM (indexed sequential access method) files are one of the three types of user files used in OpenTP1 application processing. For details about the ISAM file service, see the manual Indexed Sequential Access Method ISAM.

Organization of this subsection
(1) Overview of ISAM files
(2) Types of ISAM services

(1) Overview of ISAM files

An indexed sequential access file consists of an index part for key management and a data file part for data storage. The use of keys allows sequential access and random access processing.

An ISAM file can be manipulated by calling a library function from a UAP or by executing a utility command for ISAM file management.

(2) Types of ISAM services

The following ISAM file services can be accessed from an OpenTP1 UAP.

(a) ISAM service

ISAM files are handled as regular files. Processing is not synchronized with OpenTP1 transaction processing.

(b) ISAM/B service

ISAM files are handled in synchronization with OpenTP1 transaction processing. Use of the ISAM/B service ensures file integrity when a transaction is committed or rolled back.