notes/divers/purge_all_AWR_snap.md

Purge all AWR snapshots

To run from CDB$ROOT and not inside a PDB.

DECLARE
  v_lo_snap_id NUMBER;
  v_hi_snap_id NUMBER;
  v_awr_dbid   NUMBER;
BEGIN
  -- 1. Get the DBID that actually exists in the AWR repository
  SELECT DISTINCT dbid INTO v_awr_dbid FROM dba_hist_snapshot WHERE ROWNUM = 1;

  -- 2. Find the min and max snapshot IDs for that specific DBID
  SELECT min(snap_id), max(snap_id)
    INTO v_lo_snap_id, v_hi_snap_id
    FROM dba_hist_snapshot
   WHERE dbid = v_awr_dbid;

  IF v_lo_snap_id IS NOT NULL THEN
    DBMS_OUTPUT.PUT_LINE('Deleting snapshots for DBID ' || v_awr_dbid || 
                         ' from ' || v_lo_snap_id || ' to ' || v_hi_snap_id);
    
    DBMS_WORKLOAD_REPOSITORY.DROP_SNAPSHOT_RANGE(
      low_snap_id  => v_lo_snap_id,
      high_snap_id => v_hi_snap_id,
      dbid         => v_awr_dbid
    );
    
    DBMS_OUTPUT.PUT_LINE('AWR Snapshots cleared.');
  ELSE
    DBMS_OUTPUT.PUT_LINE('No snapshots found in dba_hist_snapshot.');
  END IF;
EXCEPTION
  WHEN TOO_MANY_ROWS THEN
    DBMS_OUTPUT.PUT_LINE('Error: Multiple DBIDs found in AWR. Please specify one manually.');
  WHEN NO_DATA_FOUND THEN
    DBMS_OUTPUT.PUT_LINE('Error: No snapshot data exists to delete.');
END;
/

Verify:

select min(snap_id),max(snap_id), dbid from dba_hist_snapshot group by dbid;

To take a snapshot:

execute dbms_workload_repository.CREATE_SNAPSHOT;