ORA-30052: invalid lower limit snapshot expression

SCOTT>select versions_startscn,versions_endscn,versions_operation,empno,sal from e versions between scn 2718926 and 2719804;
select versions_startscn,versions_endscn,versions_operation,empno,sal from e versions between scn 2718926 and 2719804
                                                       *
ERROR at line 1:
ORA-30052: invalid lower limit snapshot expression

[oracle@ora ~]$ oerr ora 30052
30052, 00000, "invalid lower limit snapshot expression"
// *Cause: The lower limit snapshot expression was below the UNDO_RETENTION
//         limit.
// *Action: Specify a valid lower limit snapshot expression.

增大UNDO_RETENTION

SYS>alter system set undo_retention=10000 scope=both;

再试一下OK：

SCOTT>select versions_startscn,versions_endscn,versions_operation,empno,sal from e versions between scn 2718926 and 2719804;

VERSIONS_STARTSCN VERSIONS_ENDSCN V      EMPNO        SAL
----------------- --------------- - ---------- ----------
          2718974                 U       7900        111
          2718974                 D       7934       1300
          2718974                 D       7839       5000
          2718974                 D       7782       2450
                                          7499       1600
                                          7521       1250
                                          7654       1250
                                          7698       2850
                          2718974         7782       2450
                          2718974         7839       5000
                                          7844       1500
                          2718974         7900        950
                          2718974         7934       1300
          2719789                 U       7934        222
          2719789                 D       7839       5000
          2718974                 I       7782       2450
          2718974         2719789 I       7839       5000
          2718974         2719789 I       7934       1300

18 rows selected.