How To Fix AD257 - Gen. buffering not allowed. Table & contains only one key field

SAP Error Message - Details

• Message type: E = Error

• Message class: AD - Data Dictionary application messages

• Message number: 257

• Message text: Gen. buffering not allowed. Table & contains only one key field

What causes this issue?

The table whose <LS>Technical settings</> you are maintaining
has only one key field. Since generic buffering calls for a number
of key fields lying between 1 and (key field number - 1), no generic
buffering is possible in this case.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Choose a different buffering type. Generic buffering is possible
only for tables with more than one key field.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message AD257 - Gen. buffering not allowed. Table & contains only one key field ?

  The SAP error message AD257 ("Gen. buffering not allowed. Table & contains only one key field") typically occurs when you attempt to enable buffering for a database table that does not meet the necessary criteria for buffering. In SAP, buffering is a performance optimization technique that allows frequently accessed data to be stored in memory, reducing the need for database access.
  Cause:
  The error arises because:
  
  The table in question has only one key field. SAP requires that tables with buffering enabled must have a primary key consisting of at least two fields or a unique key that allows for efficient data retrieval.
  The table may be defined in a way that does not support buffering due to its structure or intended use.
  
  Solution:
  To resolve this error, you can consider the following options:
  
  
  Check Table Structure: Review the structure of the table to confirm that it indeed has only one key field. If it is a custom table, you may need to modify its structure to include additional key fields.
  
  
  Disable Buffering: If the table is not suitable for buffering (e.g., it is a transactional table or has a high rate of updates), you can choose to disable buffering for that table. This can be done in the Data Dictionary (SE11):
  
  Go to the table definition.
  Navigate to the "Technical Settings" and set the buffering option to "No buffering."
  
  
  
  Re-evaluate Buffering Needs: Consider whether buffering is necessary for this table. If the table is not accessed frequently or does not benefit from buffering, it may be better to leave it unbuffered.
  
  
  Consult Documentation: Review SAP documentation or consult with your SAP Basis team for best practices regarding table buffering and performance optimization.
  
  
  Related Information:
  
  Buffering Types: SAP supports different types of buffering (single record buffering, generic buffering, etc.). Understanding these can help in deciding the right approach for your tables.
  Performance Considerations: While buffering can improve performance for read-heavy tables, it can also lead to data consistency issues if not managed properly, especially for tables that are frequently updated.
  Transaction Codes: Use transaction codes like SE11 (Data Dictionary) to view and modify table definitions, and SE14 (Database Utility) to manage database-related tasks.
  
  If you continue to face issues or if the table is part of a standard SAP application, it may be beneficial to reach out to SAP support or your internal SAP team for further assistance.