我觉得这条语句已经不能优化了,-优快云博客

本文探讨了两个具体的SQL查询案例，并对其执行计划进行了分析。通过对比不同查询语句的执行效率，提出了潜在的优化方向。

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SQL> select count(*)  from  sms.sms_asdfasdf_subscribe_log_chinamobile;

  COUNT(*)
----------
   4674

SQL> select count(*) from sms.sms_area_mobile_chinamobile;

  COUNT(*)
----------
   18040

这条语句还能优化吗?

select count(mobile) from sms.sms_asdfasdf_subscribe_log_chinamobile a, sms.sms_area_mobile_chinamobile b where b.mobile_s<=a.mobile and a.mobile<=b.mobile_e  and subscribe_flag='0' and log_date>='20080401' and log_date<='20080418235959'  ;

COUNT(MOBILE)
-------------
      2183

Elapsed: 00:00:20.61

Execution Plan
----------------------------------------------------------
0    SELECT STATEMENT Optimizer=CHOOSE
1 0 SORT (AGGREGATE)
2 1    NESTED LOOPS
3 2    TABLE ACCESS (FULL) OF 'SMS_asdfasdf_SUBSCRIBE_LOG_chinamobile'
4 2    INDEX (RANGE SCAN) OF 'IND_AREA_MOBILE_chinamobile' (NON-UNIQUE
      )

Statistics
----------------------------------------------------------
      0  recursive calls
      0  db block gets
   119363  consistent gets
      0  physical reads
      0  redo size
      524  bytes sent via SQL*Net to client
      656  bytes received via SQL*Net from client
      2  SQL*Net roundtrips to/from client
      0  sorts (memory)
      0  sorts (disk)
      1  rows processed

[ 本帖最后由 lijiebin 于 2008-4-21 09:31 编辑 ]

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