SAP DATA STORAGE - Guide

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Data Storage
ABAP programs generally work with data imported from persistent memory media to the internal session of the current program execution. This data is then available to the program as transient data. For performance reasons, data can also be stored in the shared memory of the current application server. This shared memory is available to all programs of an application server. Access to data in the shared memory is faster than accessing data in persistent memory media by some magnitude.

Persistent Data Storage

Database Accesses

Client Handling

Using Shared Memory

Using Shared Objects