{14 パフォーマンス}SQL計画ディレクティブの保存期間を変更

https://docs.oracle.com/cd/F19136_01/arpls/DBMS_SPD.html#GUID-E242EA74-6311-4A25-A92D-D47D374BC156

sqlplus test/test@pdb11

SELECT DBMS_SPD.GET_PREFS('SPD_RETENTION_WEEKS') FROM DUAL;

BEGIN
  DBMS_SPD.SET_PREFS('SPD_RETENTION_WEEKS', '4');
END;
/