what is the purpose of __STAMP column in 4D?

Question

There are two columns which are __KEY and __STAMP using by 4D. __KEY is for Primary key.

Would like to understand the usage and behavior of having the __STAMP column in 4D?

Answer 1

__STAMP is used in Wakanda's optimistic record locking. See Locking Entities in the Wakanda docs.

Answer 2

Both _KEY and _STAMP are used internally for Optimistic locking in 4D ORDA. _STAMP stores the timestamp when the entity is saved. The value increments whenever the entity is saved to the disk.4D tracks and updates this column automatically. It should not be modified. If needed, you can manually check and track the value of _STAMP to implement manual locking.