PSAPLN01 entries that appear in Detector are created by Subsystem Analyzer module SA$CDB. Whenever a Table name lookup is needed, this module inquiries the SYSIBM.SYSTABLES table (unless the table name has already been attained during the interval). Therefore:
1) Whenever Tables, Indexes, etc are accessed via the Subsystem Analyzer screens
2) Or, if a Utility job is submitted that accesses the above objects
..a PSAPLN01 entry may appear in a Detector interval.
Regarding intervals where no SQL activity takes place, nor any PSAPLN01 activity, they are not written to the Datastore.