建立存储执行计划的表
sqlplus > @ ?/rdbms/admin/utlxplan.sql
用以下语句生成某操作的执行计划：
explain plan for
select * from dual;
查看执行计划
@?/rdbms/admin/utlxpls.sql
或者
select * from table(dbms_xplan.display);
eg:
select hash_value from v$sqlarea where sql_text like 'SELECT * FROM D%';
通过消耗资源的Sql语句的hash值，通过试图v$sql_plan 查出他的执行计划
select id,parent_id pid,operation,options,object_name,cost,cardinality from
v$sql_plan where hash_value= 3433334220
eg:
select id,parent_id pid,operation,options,object_name,cost,cardinality from
v$sql_plan where hash_value='2999845277';
查询表或者索引的实际大小：
比如表有多少个数据块，有多少条记录
select blocks from dba_segments where owner='ZG' and segment_name ='表名字';
select blocks from dba_segments where owner='ZG' and segment_name='索引名字';
查询表或者索引的统计信息：
select blocks,to_char(last_analyzed,'yyyymmdd hh24:mi') from dba_tables where
owner='ZG' and table_name = 'ACC_BOOK_CHG_NOTIFY_0851';
BLOCKS TO_CHAR(LAST_A
---------- --------------
12145 20080511 20:33
SQL> select blevel,leaf_blocks,distinct_keys,num_rows,clustering_factor,to_char(last_analyzed,'yyyy
mmdd hh24:mi') from dba_indexes where owner='ZG' and index_name = 'ACC_BOOK_CHG_NOTIFY_851_I3';
BLEVEL LEAF_BLOCKS DISTINCT_KEYS NUM_ROWS CLUSTERING_FACTOR TO_CHAR(LAST_A
---------- ----------- ------------- ---------- ----------------- --------------
2 3 3 3 3 20080511 20:33
察看某表上建立的索引情况：
select index_name,column_name,column_position from dba_ind_columns where
table_owner='ZG' and table_name = 'ACC_BOOK_CHG_NOTIFY_0851' order by 1,3;
select index_name from user_indexes where TABLE_NAME='LJH';
删除索引：
drop index in_n ;