When collecting PGA statistics from Oracle databases, you might see the following error:
ORA-01427: single-row subquery returns more than one row
This usually happens in Oracle 12c or newer databases that use the multitenant (CDB/PDB) architecture.
In Oracle 12c and newer, if your database uses the multitenant feature (CDB/PDB), tables like `sys.v_$pgastat` return multiple rows for each statistic name, one for each container (root and every pluggable database). If a script expects only one row per statistic (like in older, non-CDB databases), it can break and show the ORA-01427 error.
Workaround
For Oracle 19c and higher Oracle versions, upgrade the Oracle cartridge to 8.0.0.10 or higher. This has been fixed for Oracle 19c and higher in Foglight Cloud.
Status
This issue has been logged as defect FOG-12057 and will be fixed in an upcoming release of the Oracle cartridges and Foglight Cloud for Oracle 12c and 18c monitoring.
