The APM Postgres database cemdb is filling up with thousands of empty ts_st_ts_all_dly_<date> table partitions being created.
The daily Stats Aggregation Service Stats.Aggregation.Svc, which normally starts just after midnight, was not reaching "started" state and this caused the unlimited creation of the ts_st_ts_all_dly_<date> table partitions for days and years into the future. Normally when Stats.Aggregation.Svc starts correctly only the current week's worth of partitions are created.
APM 9.x, 10.x
The Stats Aggregation Service normally runs in its own separate JVM but for a 64-bit JVM that is not necessary. The separate JVM feature was disabled as follows and that resolved the problem:
a. Stop the Enterprise Manager (EM)
b. Edit the file EM_HOME/config/tess-default.properties
c. Change the property"dailystats.aggregateInSeparateJvm=true" to be false i.e. "dailystats.aggregateInSeparateJvm=false"
NOTE: Before restarting the EM the excessive ts_st_ts_all_dly_<date> table partitions already created also need to be deleted from the cemdb
For the case that highlighted this problem it was a new install so the cemdb was dropped and new database/schema created with the EM installer.
d. Start the EM