You heard of Transient variable in Java??
Transient variable may not be serialized. In other words, we indicate JVM that, the transient variable is not saved to the database(Not persistent)
In Pega: If we mark a property as “Do not save property data”, then that property will be null when an instance containing this property is committed to the PegaRULES database.
Marking a property as transient reduces the size of the pzPVStream property and column, this in turn, improves the performance.
Note: We cannot expose a transient property as a separate column in database.