Understanding the ABAP Memory Model: Internal vs. External Memory
In SAP ABAP programming, efficient memory management is key to creating high-performance and reliable applications. The ABAP Memory Model governs how data is stored and shared during program execution. To develop optimized and maintainable code, ABAP developers must understand the differences between Internal Memory and External Memory—two fundamental concepts that define how data persists and is accessible across programs and transactions.
This article explores the ABAP Memory Model by explaining the roles, characteristics, and typical use cases of Internal and External Memory in ABAP development.
Internal Memory in ABAP is the memory area allocated to a single program or session during its runtime. It is used to store data in internal tables, variables, and work areas within that program.
You run a report that reads customer data into an internal table, processes it, and outputs results. The internal table lives only during the report execution.
External Memory refers to a shared memory area in SAP where data can be stored and accessed across multiple programs and transactions within the same user session.
ABAP offers two primary ways to store data in external memory:
CALL TRANSACTION, SUBMIT, or CALL FUNCTION).SET PARAMETER / GET PARAMETER).ABAP Memory:
EXPORT TO MEMORY ID 'ID'.IMPORT FROM MEMORY ID 'ID'.SAP Memory:
SET PARAMETER ID 'XYZ' FIELD lv_value.GET PARAMETER ID 'XYZ' FIELD lv_value.You want to pass a selected customer ID from a report to a detail transaction. Using SAP Memory (SET PARAMETER), you can store the customer ID once and retrieve it in another transaction.
| Feature | Internal Memory | External Memory |
|---|---|---|
| Scope | Single program/session | Shared across programs in user session |
| Data Persistence | Temporary; lives only during program execution | Persists until cleared or session ends |
| Usage | Temporary data processing | Data sharing between programs |
| Accessibility | Only within the running program | Across transactions or programs |
| Methods to Access | Direct internal variables | EXPORT/IMPORT TO MEMORY ID, SET/GET PARAMETER |
FREE MEMORY ID or SET PARAMETER with initial values).The ABAP Memory Model distinguishes between Internal Memory (private, temporary, program-specific) and External Memory (shared, persistent within user session). Understanding this model enables ABAP developers to design better data flows, optimize program interactions, and maintain application consistency.
| Memory Type | Purpose | Accessibility | Example Usage |
|---|---|---|---|
| Internal | Temporary, local program data | Current program only | Internal tables for calculations |
| External | Data sharing between programs | Across transactions/sessions | Passing selection parameters |
Mastering the ABAP Memory Model is fundamental to efficient ABAP programming and forms a cornerstone for building scalable SAP applications.