进入网站服务器怎么做/百度竞价托管运营
刚才作了如下测试：
1，将10g中的optimizer_mode修改为All_rows(原为choose)
2，然后比较10g和8i中同一SQL语句的执行计划
1，将10g中的optimizer_mode修改为All_rows(原为choose)
SQL> alter system set optimizer_mode=all_rows;
系统已更改。
SQL> show parameter optimizer
NAME TYPE VALUE
------------------------------------ ------- ------------------------------
optimizer_dynamic_sampling integer 2
optimizer_features_enable string 10.2.0.1
optimizer_index_caching integer 0
optimizer_index_cost_adj integer 100
optimizer_mode string ALL_ROWS
optimizer_secure_view_merging boolean TRUE
SQL>
复制代码
2，比较10g和8i中同一SQL语句的执行计划
10g中的执行计划：
SQL> set autotrace on
SQL> set autotrace traceonly
SQL> set timing on
SQL> select * from cmdba.cmcdms;
已选择3327行。
已用时间: 00: 00: 09.04
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=9 Card=3327 Bytes=
236217)
1 0 TABLE ACCESS (FULL) OF 'CMCDMS' (TABLE) (Cost=9 Card=3327
Bytes=236217)
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
256 consistent gets
0 physical reads
0 redo size
351787 bytes sent via SQL*Net to client
24956 bytes received via SQL*Net from client
446 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
3327 rows processed
SQL>
复制代码
8i中的执行计划：
SQL> set autotrace on
SQL> set autotrace traceonly
SQL> set timing on
SQL> select * from cmdba.cmcdms;
已选择3330行。
已用时间: 00: 00: 01.56
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 TABLE ACCESS (FULL) OF 'CMCDMS'
Statistics
----------------------------------------------------------
0 recursive calls
4 db block gets
367 consistent gets
0 physical reads
0 redo size
349893 bytes sent via SQL*Net to client
24956 bytes received via SQL*Net from client
223 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
3330 rows processed
SQL>
复制代码
对于执行计划，不是很懂，各位高手，是否能给看一下，是否能看出点问题!
还要说明一点：8i的DB是当前使用的，有负载，10g的还没有使用，只是测试，没有负载!