###############测试插入 删除 更新表的日志开销
建立表
SYS@orcl >create table ssr(id int);
查询表空间，sys默认system,插入数据后此分配空间
SYS@orcl >select tablespace_name, segment_name from user_segments where segment_name='SSR';
TABLESPACE_NAME SEGMENT_NAME
---------------------------------------------------------
SYSTEM SSR
建立空表
GUOYF@orcl 09:20:01>create table aa as select * from all_objects where 1=0;
查询现有日志大小
select a.name,b.value from v$statname a join v$mystat b on a.statistic#=b.statistic# where a.name='redo size';
NAME VALUE
---------------------------------------------------------------- ----------
redo size 254388
插入数据
GUOYF@orcl 09:24:01>insert into aa select * from all_objects where rownum<100;
查询日志大小
select a.name,b.value from v$statname a join v$mystat b on a.statistic#=b.statistic# where a.name='redo size';
NAME VALUE
---------------------------------------------------------------- ----------
redo size 268768
更新数据
GUOYF@orcl 09:27:47>update aa set owner='guoyf' where owner='SYS';
查看日志大小
select a.name,b.value from v$statname a join v$mystat b on a.statistic#=b.statistic# where a.name='redo size';
NAME VALUE
---------------------------------------------------------------- ----------
redo size 294612
删除数据
GUOYF@orcl 09:29:10>delete from aa where owner='guoyf';
查看日志大小
select a.name,b.value from v$statname a join v$mystat b on a.statistic#=b.statistic# where a.name='redo size';
NAME VALUE
---------------------------------------------------------------- ----------
redo size 330832
经过以上数据代表产生日志量
删除》更新》插入
AUTOTRACE是一个SQL*Plus工具,用于跟踪SQL的执行计划,收集执行时所耗用资源的统计信息
set autotrace off :缺省值，将不生成autotrace 报告
set autotrace on :包含执行计划和统计信息
set autotrace traceonly :等同于set autotrace on，但不显示查询输出的结果
set autotrace on explain :只显示优化器执行路径报告
set autotrace on statistics :只显示执行统计信息
#######测试delete没法释放表空间
建立表
SQL> create table bb as select * from dba_objects;
开启啊autotrace
SQL> set autotrace on ;
##查看I/O
SQL> select count(*) from bb;
COUNT(*)
----------
72573
Execution Plan
----------------------------------------------------------
Plan hash value: 162157452
-------------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 290 (1)| 00:00:04 |
| 1 | SORT AGGREGATE | | 1 | | |
| 2 | TABLE ACCESS FULL| BB | 69590 | 290 (1)| 00:00:04 |
-------------------------------------------------------------------
Note
-----
- dynamic sampling used for this statement (level=2)
Statistics
----------------------------------------------------------
28 recursive calls
0 db block gets
1106 consistent gets
1034 physical reads
0 redo size
528 bytes sent via SQL*Net to client
523 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
关闭啊autotrace
SQL> set autotrace off;
删除表
SQL> delete from bb;
72653 rows deleted.
SQL> select count(*) from bb;
COUNT(*)
----------
0
SQL> commit;
Commit complete.
SQL> set autotrace on;
SQL> select count(*) from bb;
COUNT(*)
----------
0
Execution Plan
----------------------------------------------------------
Plan hash value: 162157452
-------------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 289 (0)| 00:00:04 |
| 1 | SORT AGGREGATE | | 1 | | |
| 2 | TABLE ACCESS FULL| BB | 1 | 289 (0)| 00:00:04 |
-------------------------------------------------------------------
Note
-----
- dynamic sampling used for this statement (level=2)
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
1039 consistent gets
0 physical reads
0 redo size
525 bytes sent via SQL*Net to client
523 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> truncate table bb;
Table truncated.
SQL> select count(*) from bb;
COUNT(*)
----------
0
Execution Plan
----------------------------------------------------------
Plan hash value: 162157452
-------------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 2 (0)| 00:00:01 |
| 1 | SORT AGGREGATE | | 1 | | |
| 2 | TABLE ACCESS FULL| BB | 1 | 2 (0)| 00:00:01 |
-------------------------------------------------------------------
Note
-----
- dynamic sampling used for this statement (level=2)
Statistics
----------------------------------------------------------
20 recursive calls
1 db block gets
10 consistent gets
0 physical reads
96 redo size
525 bytes sent via SQL*Net to client
523 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
c#