Persistence ID

A Persistence ID is a unique and stable identifier assigned to each entity in the system. It serves as a consistent reference that allows you to retrieve, update, or interact with a specific entity—independent of its internal structure or database key configuration.

By abstracting away underlying database keys, the persistenceId ensures entities can be referenced across different parts of the application and through APIs.

Single Primary Key

For entities with a single primary key, the persistenceId is identical to that key’s value.

Example:
If an entity’s primary key is id = 42, then: persistenceId = "42"

Multiple Primary Keys

For entities with composite (multiple) primary keys, the persistenceId is a Base64 –encoded JSON string representing the key–value pairs.

Example:

• Original JSON:

  {"pk1": "value1", "pk2": "value2"}

• Base64 encoded:

  eyJwazEiOiAidmFsdWUxIiwgInBrMiI6ICJ2YWx1ZTIifQ==