索引组织表
索引组织表的存储结构是按照主键的B-tree 结构搭建的。不象普通的表（堆 积表——数据的存储是无序进行的），索引组织表中的数据是按照主键的 B-tree 结构排序后保存的。包括保存索引组织表行的主键字段值在内，B-tree 中的每一 个索引项还保存了非键字段的值。
组织索引表实际上就是索引的表化
为什么要引进组织索引表
create table org_index_table
( object_id int primary key,
oname varchar2(30),
owner varchar2(30),
status varchar2(30))
organization index;
create table heap_table
( object_id int primary key,
oname varchar2(30),
owner varchar2(30),
status varchar2(30)
)
alter table org_index_table nologging;
alter table heap_table nologging;
create table s_table as
select object_id, object_name, owner,status
from all_objects
insert into heap_table select * from s_table
call count cpu elapsed disk query current rows
------- ------ -------- -------------------- ---------- ---------- ----------
Parse 1 0.01 0.00 0 1 0 0
Execute 1 0.48 0.62 90 2301 11134 70231
Fetch 0 0.00 0.00 0 0 0 0
------- ------ -------- -------------------- ---------- ---------- ----------
total 2 0.50 0.63 90 2302 11134 70231
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: 114
Rows Row Source Operation
------- ---------------------------------------------------
0 LOAD TABLE CONVENTIONAL (cr=2575 pr=90 pw=90 time=0 us)
70231 TABLE ACCESS FULL S_TABLE (cr=450 pr=88pw=88 time=1380 us cost=128 size=4239300 card=81525)
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
db file scattered read 16 0.08 0.14
db file sequential read 8 0.01 0.02
log file sync 1 0.00 0.00
SQL*Net message to client 1 0.00 0.00
SQL*Net message from client 1 0.00 0.00
Insert into org_index_table select* from s_table
call count cpu elapsed disk query current rows
------- ------ -------- -------------------- ---------- ---------- ----------
Parse 1 0.00 0.00 0 1 0 0
Execute 1 0.39 0.57 0 2389 10939 70231
Fetch 0 0.00 0.00 0 0 0 0
------- ------ -------- -------------------- ---------- ---------- ----------
total 2 0.39 0.57 0 2390 10939 70231
Rows Row Source Operation
------- ---------------------------------------------------
0 LOAD TABLE CONVENTIONAL (cr=2535 pr=0 pw=0 time=0 us)
70231 TABLE ACCESS FULL S_TABLE (cr=450 pr=0 pw=0time=1079 us cost=128 size=4239300 card=81525)
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- --------