SQL> select count(*) from wl;

  COUNT(*)
----------
     29676

SQL> delete from wl where rownum<10000;

已删除9999行。

SQL> commit;

提交完成。

SQL> select count(*) from wl;

  COUNT(*)
----------
     19677

SQL> select last_analyzed,empty_blocks from user_tables where table_name='WL';

LAST_ANALYZED       EMPTY_BLOCKS
------------------- ------------

SQL> exec dbms_stats.gather_table_stats('test','wl');

PL/SQL 过程已成功完成。

SQL> select last_analyzed,empty_blocks from user_tables where table_name='WL';

LAST_ANALYZED       EMPTY_BLOCKS
------------------- ------------
2009-02-01 16:51:30            0

SQL> analyze table wl compute statistics;

表已分析。

SQL> select last_analyzed,empty_blocks from user_tables where table_name='WL';

LAST_ANALYZED       EMPTY_BLOCKS
------------------- ------------
2009-02-01 16:51:51          106

这是metalink上对该字段统计不一样的解释：Dbms_stats performs differently with analyst statement, the output will be different.
Empty_blocks in dba_tables is the number of blocks that are allocated but were never used. These blocks will not be read anyway as it is beyond the high water mark.
Avg_space and Avg_space_freelist_blocks are use for space management and inserts, it does not affect the optimi