恢复统计信息操作也存在一些限制，比如无法恢复用户自定义的统计信息。除此之外由于统计信息是表的属性，因此如果表被删除，则对应的统计备份也被清除，而TRUNCATE操作则并不会影响统计备份信息：
SQL> CREATE TABLE T (ID NUMBER);
Table created.
SQL> INSERT INTO T SELECT ROWNUM FROM TAB;
96 rows created.
SQL> EXEC DBMS_STATS.GATHER_TABLE_STATS(USER, 'T')
PL/SQL procedure successfully completed.
SQL> SELECT TABLE_NAME, NUM_ROWS, BLOCKS, LAST_ANALYZED
2 FROM USER_TABLES
3 WHERE TABLE_NAME = 'T';
TABLE_NAME NUM_ROWS BLOCKS LAST_ANALYZED
------------------------------ ---------- ---------- --------------
T 96 5 25-10月-10
SQL> SELECT TABLE_NAME, STATS_UPDATE_TIME
2 FROM USER_TAB_STATS_HISTORY
3 WHERE TABLE_NAME = 'T';
TABLE_NAME STATS_UPDATE_TIME
------------------------------ -----------------------------------------------------------
T 25-10月-1010.55.10.109647下午+08:00
SQL> TRUNCATE TABLE T;
Table truncated.
SQL> INSERT INTO T SELECT ROWNUM FROM USER_OBJECTS;
242 rows created.
SQL> COMMIT;
Commit complete.
SQL> EXEC DBMS_STATS.GATHER_TABLE_STATS(USER, 'T')
PL/SQL procedure successfully completed.
SQL> ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS';
Session altered.
SQL> SELECT TABLE_NAME, NUM_ROWS, BLOCKS, LAST_ANALYZED
2 FROM USER_TABLES
3 WHERE TABLE_NAME = 'T';
TABLE_NAME NUM_ROWS BLOCKS LAST_ANALYZED
------------------------------ ---------- ---------- -------------------
T 242 5 2010-10-25 22:56:39
SQL> SELECT TABLE_NAME, STATS_UPDATE_TIME
2 FROM USER_TAB_STATS_HISTORY
3 WHERE TABLE_NAME = 'T';
TABLE_NAME STATS_UPDATE_TIME
------------------------------ -----------------------------------------------------------
T 25-10月-1010.55.10.109647下午+08:00
T 25-10月-10 10.56.39.079646下午+08:00
SQL> DROP TABLE T PURGE;
Table dropped.
SQL> CREATE TABLE T (ID NUMBER);
Table created.
SQL> INSERT INTO T SELECT ROWNUM FROM TAB;
96 rows created.
SQL> COMMIT;
Commit complete.
SQL> EXEC DBMS_STATS.GATHER_TABLE_STATS(USER, 'T')
PL/SQL procedure successfully completed.
SQL> SELECT TABLE_NAME, STATS_UPDATE_TIME