Oracle脚本检查对象空间使用情况
TOM有个非常好的查看对象空间使用情况的脚本show_space.sql，下面将介绍。
这里介绍的是相对而言比较简单的，下面演示中其实是针对表的空间信息，至于对象的，我将在下面改写。
下面例子演示的是delete和truncate对高水位的影响，其中用到了脚本space_usage.sql。
[oracle@maa3 ~]$ cat space_usage.sql
-- space_usage.sql
declare
l_tabname varchar2(30) := '&1';
l_fs1_bytes number;
l_fs2_bytes number;
l_fs3_bytes number;
l_fs4_bytes number;
l_fs1_blocks number;
l_fs2_blocks number;
l_fs3_blocks number;
l_fs4_blocks number;
l_full_bytes number;
l_full_blocks number;
l_unformatted_bytes number;
l_unformatted_blocks number;
begin
dbms_space.space_usage(
segment_owner => user,
segment_name => l_tabname,
segment_type => 'TABLE',
fs1_bytes => l_fs1_bytes,
fs1_blocks => l_fs1_blocks,
fs2_bytes => l_fs2_bytes,
fs2_blocks => l_fs2_blocks,
fs3_bytes => l_fs3_bytes,
fs3_blocks => l_fs3_blocks,
fs4_bytes => l_fs4_bytes,
fs4_blocks => l_fs4_blocks,
full_bytes => l_full_bytes,
full_blocks => l_full_blocks,
unformatted_blocks => l_unformatted_blocks,
unformatted_bytes => l_unformatted_bytes
);
dbms_output.put_line('0-25% Free = '||l_fs1_blocks||' Bytes = '||l_fs1_bytes);
dbms_output.put_line('25-50% Free = '||l_fs2_blocks||' Bytes = '||l_fs2_bytes);
dbms_output.put_line('50-75% Free = '||l_fs3_blocks||' Bytes = '||l_fs3_bytes);
dbms_output.put_line('75-100% Free = '||l_fs4_blocks||' Bytes = '||l_fs4_bytes);
dbms_output.put_line('Full Blocks = '||l_full_blocks||' Bytes = '||l_full_bytes);
end;
/
查看给T1表分配了多少数据块儿
luocs@MAA> select blocks from user_segments where segment_name='T1';
# Blocks
---------------
384
列出包含数据的数据块儿数
luocs@MAA> select count(distinct(dbms_rowid.rowid_block_number(rowid))) block_count from t1;
BLOCK_COUNT
---------------
306
查询lowest block number和highest block number
luocs@MAA> select min(dbms_rowid.rowid_block_number(rowid)) min_block, max(dbms_rowid.rowid_block_number(rowid)) max_block from t1;
MIN_BLOCK MAX_BLOCK
--------------- ---------------
131 447
luocs@MAA> @space_usage T1
0-25% Free = 0 Bytes = 0
25-50% Free = 0 Bytes = 0
50-75% Free = 0 Bytes = 0
75-100% Free = 0 Bytes = 0
Full Blocks = 306 Bytes = 2506752
大家在使用过程中，可能会遇到ORA-00942: table or view does not exist、ORA-06512: at "SYS.DBMS_SPACE", line 214的错误，这是因为大家表名使用了小写，比如：
luocs@MAA> @space_usage t1
declare
*
ERROR at line 1:
ORA-00942: table or view does not exist
ORA-06512: at "SYS.DBMS_SPACE", line 214
ORA-06512: at line 16
为更加方便，我稍微修改了下脚本，此脚本可在dba权限用户下使用，需要提供模式和表名
sys@MAA> get space
1 declare
2 l_user varchar2(30) := upper('&1');
3 l_tabname varchar2(30) := upper('&2');
4 l_fs1_bytes number;
5 l_fs2_bytes number;
6 l_fs3_bytes number;
7 l_fs4_bytes number;
8 l_fs1_blocks number;
9 l_fs2_blocks number;
10 l_fs3_blocks number;
11 l_fs4_blocks number;
12 l_full_bytes number;
13 l_full_blocks number;
14 l_unformatted_bytes number;
15 l_unformatted_blocks number;
16 begin
17 dbms_space.space_usage(
18 segment_owner => l_user,
19 segment_name => l_tabname,
20 segment_type => 'TABLE',
21 fs1_bytes => l_fs1_bytes,
22 fs1_blocks => l_fs1_blocks,
23 fs2_bytes => l_fs2_bytes,
24 fs2_blocks => l_fs2_blocks,
25 fs3_bytes => l_fs3_bytes,
26 fs3_blocks => l_fs3_blocks,
27 fs4_bytes => l_fs4_bytes,
28 fs4_blocks => l_fs4_blocks,
29 full_bytes => l_full_bytes,
30 full_blocks => l_full_blocks,
31 unformatted_blocks => l_unformatted_blocks,
32 unformatted_bytes => l_unformatted_bytes
33 );
34 dbms_output.put_line('0-25% Free = '||l_fs1_blocks||' Bytes = '||l_fs1_bytes);
35 dbms_output.put_line('25-50% Free = '||l_fs2_blocks||' Bytes = '||l_fs2_bytes);
36 dbms_output.put_line('50-75% Free = '||l_fs3_blocks||' Bytes = '||l_fs3_bytes);
37 dbms_output.put_line('75-100% Free = '||l_fs4_blocks||' Bytes = '||l_fs4_bytes);
38 dbms_output.put_line('Full Blocks = '||l_full_blocks||' Bytes = '||l_full_bytes);
39* end;
sys@MAA> @space luocs t1
old 2: l_user varchar2(30) := upper('&1');
new 2: l_user varchar2(30) := upper('luocs');
old 3: l_tabname varchar2(30) := upper('&2');
new 3: l_tabname varchar2(30) := upper('t1');
0-25% Free = 0 Bytes = 0
25-50% Free = 0 Bytes = 0
50-75% Free = 0 Bytes = 0
75-100% Free = 0 Bytes = 0
Full Blocks = 306 Bytes = 2506752
PL/SQL procedure successfully completed.
先用delete删除t1表所有数据
sys@MAA> delete from luocs.t1;
22671 rows deleted.
sys@MAA> commit;
Commit complete.
sys@MAA> select blocks from dba_segments where owner='LUOCS' and segment_name='T1';
BLOCKS
----------
384
sys@MAA> select count(distinct(dbms_rowid.rowid_block_number(rowid))) block_count from luocs.t1;
BLOCK_COUNT
-----------
0
sys@MAA> @space luocs t1
old 2: l_user varchar2(30) := upper('&1');
new 2: l_user varchar2(30) := upper('luocs');
old 3: l_tabname varchar2(30) := upper('&2');
new 3: l_tabname varchar2(30) := upper('t1');
0-25% Free = 0 Bytes = 0
25-50% Free = 0 Bytes = 0
50-75% Free = 0 Bytes = 0
75-100% Free = 306 Bytes = 2506752
Full Blocks = 0 Bytes = 0
PL/SQL procedure successfully completed.
但因为DELETE并不降低HWM，所以做FTS 扫描的I/O块儿依然多
sys@MAA> set autot traceonly exp stat
sys@MAA> select * from luocs.t1;
no rows selected
Execution Plan
----------------------------------------------------------
Plan hash value: 3617692013
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 22671 | 2036K| 88 (0)| 00:00:02 |
| 1 | TABLE ACCESS FULL| T1 | 22671 | 2036K| 88 (0)| 00:00:02 |
--------------------------------------------------------------------------
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
309 consistent gets
0 physical reads
0 redo size
1343 bytes sent via SQL*Net to client
512 bytes received via SQL*Net from client
1 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
0 rows processed
sys@MAA> set autot off
然后truncate这张表
sys@MAA> truncate table luocs.t1;
Table truncated.
sys@MAA> @space luocs t1
old 2: l_user varchar2(30) := upper('&1');
new 2: l_user varchar2(30) := upper('luocs');
old 3: l_tabname varchar2(30) := upper('&2');
new 3: l_tabname varchar2(30) := upper('t1');
0-25% Free = 0 Bytes = 0
25-50% Free = 0 Bytes = 0
50-75% Free = 0 Bytes = 0
75-100% Free = 0 Bytes = 0
Full Blocks = 0 Bytes = 0
PL/SQL procedure successfully completed.
sys@MAA> select blocks from dba_segments where owner='LUOCS' and segment_name='T1';
BLOCKS
----------
8
再进行FTS，逻辑读降低
sys@MAA> set autot traceonly exp stat
sys@MAA> select * from luocs.t1;
no rows selected
Execution Plan
----------------------------------------------------------
Plan hash value: 3617692013
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 22671 | 2036K| 88 (0)| 00:00:02 |
| 1 | TABLE ACCESS FULL| T1 | 22671 | 2036K| 88 (0)| 00:00:02 |
--------------------------------------------------------------------------
Statistics
----------------------------------------------------------
1 recursive calls
0 db block gets
1 consistent gets
0 physical reads
0 redo size
1343 bytes sent via SQL*Net to client
512 bytes received via SQL*Net from client
1 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
0 rows processed
至于ROWS依然显示22671是因为没有进行分析
sys@MAA> exec dbms_stats.gather_table_stats('LUOCS','T1',cascade=>true);
PL/SQL procedure successfully completed.
sys@MAA> select * from luocs.t1;
no rows selected
Execution Plan
----------------------------------------------------------
Plan hash value: 3617692013
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 207 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS FULL| T1 | 1 | 207 | 2 (0)| 00:00:01 |
--------------------------------------------------------------------------
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
1 consistent gets
0 physical reads
0 redo size
1343 bytes sent via SQL*Net to client
512 bytes received via SQL*Net from client
1 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
0 rows processed
sys@MAA> select count(*) from luocs.t1;
COUNT(*)
----------
45594
sys@MAA> exec dbms_stats.gather_table_stats('LUOCS','T1',cascade=>true);
PL/SQL procedure successfully completed.
sys@MAA> exec dbms_stats.gather_index_stats('LUOCS','INX_ID');
PL/SQL procedure successfully completed.
oracle视频教程请关注:http://u.youku.com/user_video/id_UMzAzMjkxMjE2.html