When working with Acumatica ERP, developers may encounter concurrency errors during database operations. One common error message that might appear is:

"Error: Another process has updated the {YourTable} record. Your changes will be lost."

This issue can arise in various scenarios, especially when multiple processes attempt to update the same record concurrently. It’s crucial to manage these operations carefully to ensure data integrity and avoid conflicts.

Why Does This Error Occur?

In Acumatica, when you attempt to update a record that has been modified by another process, a concurrency conflict occurs. Acumatica uses timestamps to track changes to records. Each time a record is updated, its timestamp is modified. If you try to update a record that has a different timestamp from what was originally retrieved, Acumatica will throw a concurrency error to prevent you from accidentally overwriting changes made by another user or process.

Understanding the PXDBTimestamp Attribute

The PXDBTimestamp attribute plays a critical role in managing concurrency in Acumatica. This attribute is applied to a DAC (Data Access Class) field, binding it to a timestamp column in the database.

Key Points About PXDBTimestamp:

●     Timestamp Tracking: The database timestamp is a counter that increments with each insert or update operation. It doesn't represent actual time but a relative change count within the database.

●     Concurrency Control: The timestamp allows Acumatica to detect if the record has been modified since it was last read. If the timestamp doesn't match, Acumatica knows that another process has updated the record, which triggers the error.

●     Binding: The attribute binds the field to the corresponding database column, ensuring that the timestamp is correctly managed during insert and update operations.

Here’s how you can declare a timestamp field in a DAC:

using PX.Data.BQL;

#region Tstamp

[PXDBTimestamp()]

[PXUIField(DisplayName = "Tstamp")]

public virtual byte[] Tstamp { get; set; }

public abstract class tstamp : BqlByteArray.Field<tstamp> { }

#endregion

Common Concurrency Issue: Incorrect Handling of Persist Operations

A typical scenario where this error can occur is during the Persist operation in custom code. If the timestamp is not properly managed, concurrency issues can arise.

The Correct Way to Handle Persist Operations

To avoid concurrency errors, you should ensure that the timestamp is properly selected before saving any changes. Here’s how you can correctly handle the Persist method:

In this approach, the SelectTimeStamp method is called before the base Persist method. This ensures that the latest timestamp is retrieved, preventing conflicts when updates are made.

What Happens If You Don’t Handle Timestamps Correctly

If you skip the timestamp selection, as shown in the code snippet below, you might encounter concurrency issues:

In this case, if the record was updated by another process before your changes were saved, the operation will fail with a concurrency error, leading to potential data loss or inconsistency.

Conclusion

Effective concurrency management in Acumatica hinges on proper timestamp handling. Utilizing the SelectTimeStamp method to refresh a record’s timestamp before making changes can help prevent common issues associated with concurrent updates. Incorporating the PXDBTimestamp attribute in your customizations further ensures that data updates are managed safely, reducing the risk of errors and preserving data integrity.

By mastering these practices, you can enhance the robustness and reliability of your ERP solutions, ensuring that your customizations handle concurrent modifications effectively.