真的是写了一天的作业。
2.模拟PPT中的例子，做一个绑定变量和非绑定变量的资源消耗对比示例，给出过程和结果。可以使用latch_test.txt文档中提供的脚本。
实验环境：
数据库oracle 11gR2 系统：linux6.2
结果：
Name Run1 Run2 Diff
LATCH.corrupted undo seg latch 1,712 160 -1,552
STAT...parse time elapsed 1,775 79 -1,696
STAT...Elapsed Time 1,845 92 -1,753
STAT...DB time 1,849 74 -1,775
LATCH.DML lock allocation 1,918 113 -1,805
LATCH.redo allocation 1,929 118 -1,811
STAT...opened cursors cumulati 1,868 15 -1,853
STAT...execute count 1,870 17 -1,853
STAT...parse count (total) 1,871 17 -1,854
STAT...parse count (hard) 1,859 3 -1,856
STAT...calls to get snapshot s 1,874 14 -1,860
STAT...enqueue releases 1,867 5 -1,862
STAT...enqueue requests 1,868 5 -1,863
LATCH.SQL memory manager worka 2,233 109 -2,124
LATCH.cache buffers lru chain 2,687 229 -2,458
LATCH.object queue header oper 3,007 239 -2,768
LATCH.session allocation 3,867 227 -3,640
LATCH.In memory undo latch 3,926 283 -3,643
LATCH.kks stats 3,729 5 -3,724
LATCH.enqueues 4,075 8 -4,067
LATCH.shared pool simulator 4,749 19 -4,730
LATCH.simulator hash latch 5,818 220 -5,598
LATCH.enqueue hash chains 6,059 125 -5,934
LATCH.session idle bit 6,508 284 -6,224
STAT...recursive calls 7,534 118 -7,416
LATCH.row cache objects 34,628 1,046 -33,582
STAT...session uga memory max 123,452 65,512 -57,940
STAT...session uga memory 65,512 0 -65,512
LATCH.shared pool 85,903 532 -85,371
LATCH.cache buffers chains 101,552 4,652 -96,900
Run1 latches total versus runs -- difference and pct
Run1 Run2 Diff Pct
277,204 8,831 -268,373 3,138.99%
3.用示例说明表数据中出现热块的场景，并给出解决方案。
TEST@orcl> create table masicong (id number,name varchar(10));
Table created.
TEST@orcl>insert into masicong values(1,'masicong1');
1 row created.
TEST@orcl> insert into masicong values(2,'masicong2')；
TEST@orcl> commit;
Commit complete.
TEST@orcl> select dbms_rowid.ROWID_RELATIVE_FNO(rowid) file# from masicong;
FILE#
----------
4
TEST@orcl> select dbms_rowid.ROWID_RELATIVE_FNO(rowid) file#,dbms_rowid.ROWID_BLOCK_NUMBER(rowid) block# from masicong;
FILE# BLOCK#
---------- ----------
4 542
4 542
TEST@orcl> select sid from v$mystat where rownum=1;
SID
----------
59
TEST@orcl> declare
2 i number:=0;
3 begin
4 loop
5 update masicong set name='masicong4' where id=2;
6 i:=i+1;
7 if mod(i,100)=0 then
8 commit;
9 end if;
10 end loop;
11 end;
12 /
TEST@orcl> select sid from v$mystat where rownum=1;
SID
----------
30
declare
i number:=0;
begin
loop
update masicong set name='masicong3' where id=1;
i:=i+1;
if mod(i,100)=0 then
commit;
end if;
end loop;
end;
/
SYS@orcl> select s.sid,w.event from v$session s,v$session_wait w where s.sid=w.sid and s.status='ACTIVE';
SID EVENT
---------- ----------------------------------------------------------------
1 latch: session allocation
2 pmon timer
3 VKTM Logical Idle Wait
4 rdbms ipc message
5 DIAG idle wait
6 rdbms ipc message
7 rdbms ipc message
8 DIAG idle wait
9 rdbms ipc message
10 rdbms ipc message
11 rdbms ipc message
SID EVENT
---------- ----------------------------------------------------------------
12 rdbms ipc message
13 smon timer
14 rdbms ipc message
15 rdbms ipc message
16 rdbms ipc message
20 Streams AQ: qmn coordinator idle wait
24 rdbms ipc message
25 Streams AQ: qmn slave idle wait
27 Streams AQ: waiting for messages in the queue
29 Streams AQ: waiting for time management or cleanup tasks
30 buffer busy waits
SID EVENT
---------- ----------------------------------------------------------------
38 wait for unread message on broadcast channel
40 SQL*Net message to client
41 latch: session allocation
42 Space Manager: slave idle wait
43 rdbms ipc message
59 latch: cache buffers chains
28 rows selected.
SYS@orcl> select sql_text from v$sql t1,v$session t2,v$session_wait t3
where t1.address=t2.sql_address and t1.hash_value=t2.sql_hash_value
3 and t2.sid=t3.sid and t3.event='buffer busy waits';
SQL_TEXT
---------------------------------------------------
UPDATE MASICONG SET NAME='masicong3' WHERE ID=1
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