关于生产库上索引碎片收集的问题 <整理 from askmaclean >

问题描述：

环境：oracle10.2.0.5 RAC+HP-UX
用analyze index <index_name> validate structure这个语句可以验证索引的碎片程度，然后通过index_stats视图来查询，请问这个语句在生产库上对于比较大的索引使用这个语句，对系统的影响有多大？

FYI：

analyze index <index_name> validate structure

SQL> create table ttab(t1 int);

Table created.

SQL> create index ind_tab on ttab(t1);

Index created.

SQL> oradebug setmypid
Statement processed.
SQL> oradebug event 10704 trace name context forever,level 10;
Statement processed.


SQL> analyze index ind_tab validate structure;

Index analyzed.

SQL> oradebug tracefile_name
/s01/admin/G10R25/udump/g10r25_ora_25784.trc


[root@vrh8 ~]# grep "ksqgtl \*\*\*" /s01/admin/G10R25/udump/g10r25_ora_25784.trc
ksqgtl *** TX-00030007-000071e6 mode=6 flags=0x401 timeout=0 ***
ksqgtl *** TM-00010183-00000000 mode=4 flags=0x401 timeout=0 ***

analyze index <index_name> validate structure 要在table上加 TM mode=4的share lock，会block dml

second：

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> oradebug setmypid
Statement processed.
SQL> oradebug event 10704 trace name context forever,level 10;
Statement processed.
SQL> analyze index ind_tab validate structure online;

Index analyzed.

SQL> oradebug tracefile_name
/s01/admin/G10R25/udump/g10r25_ora_25830.trc

[root@vrh8 ~]# grep "ksqgtl \*\*\*" /s01/admin/G10R25/udump/g10r25_ora_25830.trc
ksqgtl *** TX-0009002d-000072d7 mode=6 flags=0x401 timeout=0 ***


SQL> select * from index_stats;

no rows selected

analyze index ind_tab validate structure online ==> 不要求 表上的 share lock，但是不填充index_stats 视图， 所以 validate structure online 只能用来验证索引上是否存在讹误