Oracle’s DBMS_PRofiler:PL/SQL 性能調(diào)整
DBMS_PROFILER 包舉例
下面是我提供的怎樣使用配置的簡(jiǎn)單例子,運(yùn)行配置文件來(lái)測(cè)試下面例程的性能. 例程用到的自定義腳本緊隨其后.
1. 創(chuàng)建過(guò)程.
create or replace procedure am_perf_chk (pi_seq in number,
pio_status in out nocopy varchar2) is
l_dat date := sysdate;
begin
if trunc(l_dat) = '21-sep-02' and pi_seq = 1 then
pio_status := 'OK';
else
pio_status := 'Invalid tape loaded';
end if;
exception
when others then
pio_status := 'Error in am_perf_chek';
end;
2. 用配置文件調(diào)用例程
替換上面的例程, 執(zhí)行call_profiler.sql腳本(腳本代碼參見(jiàn)下面),傳入pi_seq=2
SQL> @d:/am/call_profiler.sql
Profiler started
Invalid tape loaded
PL/SQL procedure sUCcessfully completed.
Profiler stopped
Profiler flushed
runid:8
3. 評(píng)估執(zhí)行時(shí)間:
執(zhí)行eavluate_profiler_results.sql腳本,得到時(shí)間統(tǒng)計(jì)
SQL> @d:/am/evaluate_profiler_results.sql
Enter value for runid: 8
Enter value for name: am_perf_chk
Enter value for owner: scott
Line Occur Msec Text
---------- ---------- ---------- -------------------------------------------------------------------
1 procedure am_perf_chk (pi_seq in number,
2 pio_status in out nocopy varchar2) is
3 2 43.05965 l_dat date := sysdate;
4 begin
5 1 86.35732 if trunc(l_dat) = '21-sep-02' and pi_seq = 1 then
6 0 0 pio_status := 'OK';
7 else
8 1 8.416151 pio_status := 'Invalid tape loaded';
9 end if;
10 exception
11 when others then
12 0 0 pio_status := 'Error in am_perf_chek';!
13 1 2.410361 end;
13 rows selected.
Code% coverage
--------------
66.6666667
4. 正如你看到的,第三行執(zhí)行時(shí)間提高到86毫秒.但是改變if語(yǔ)句,重新執(zhí)行上面的過(guò)程,將會(huì)得到新的結(jié)果:
Line Occur Msec Text
---------- ---------- ---------- -------------------------------------------------------------------
1 procedure am_perf_chk (pi_seq in number,
2 pio_status in out nocopy varchar2) is
3 2 17.978816 l_dat date := sysdate;
4 begin
5 1 8.419503 if pi_seq = 1 and trunc(l_dat) = '21-sep-02' then
6 0 0 pio_status := 'OK';
7 else
8 1 7.512684 pio_status := 'Invalid tape loaded';
9 end if;
10 exception
11 when others then
12 0 0 pio_status := 'Error in !am_perf_chek';
13 1 .731657 end;
13 rows selected.
Code% coverage
--------------
66.6666667
5. 正如你看到的, 這種情境下第三行執(zhí)行時(shí)間從86毫秒減少到8毫秒,多余的時(shí)間是由于內(nèi)置trunc()函數(shù)引起., 這種情境下假如第一個(gè)條件為false,則不會(huì)執(zhí)行trunc()函數(shù).這僅僅是個(gè)簡(jiǎn)單的例子,當(dāng)你測(cè)試的例程越大,你面臨的挑戰(zhàn)更大.
這個(gè)配置結(jié)果也證實(shí)了執(zhí)行期間代碼被覆蓋多少行,從而讓我們知道處于性能監(jiān)視中的代碼范圍。
假如任何PL/SQL塊性能出現(xiàn)問(wèn)題，它也能提煉出各種不同情景的正在在執(zhí)行的代碼并檢查配置結(jié)果，從而查明問(wèn)題所在。
6. 對(duì)于一個(gè)特定的情景，假如執(zhí)行一段非凡的代碼段，可以得到合理的分析，即使代碼根本一點(diǎn)都不能運(yùn)行。
環(huán)境的創(chuàng)建
默認(rèn)安裝或數(shù)據(jù)庫(kù)的創(chuàng)建狀態(tài)下，DBMS_PROFILER包不會(huì)自動(dòng)安裝，請(qǐng)DBA用profload.sql腳本創(chuàng)建它.用一個(gè)權(quán)限較大的或一個(gè)單獨(dú)的用戶，創(chuàng)建存儲(chǔ)統(tǒng)計(jì)信息的表。假如
用如SYS用戶創(chuàng)建，則給其它用戶授予DML權(quán)限，并且對(duì)這些表創(chuàng)建一個(gè)共同的簡(jiǎn)寫(xiě)名.
創(chuàng)建表的如下:
PLSQL_PROFILER_RUNS表:PL/SQL配置的運(yùn)行細(xì)節(jié).
PLSQL_PROFILER_UNITS表:運(yùn)行中每一個(gè)庫(kù)單元的信息.
PLSQL_PROFILER_DATA表:所有配置文件運(yùn)行時(shí)的數(shù)據(jù)累積.
PLSQL_PROFILER_RUNNUMBER序列提供了RUNID
運(yùn)行和解釋配置數(shù)據(jù)
ORACLE提供了三個(gè)表來(lái)統(tǒng)計(jì)，填充RUNID。有許多第三方的工具可以提供自定義的基于這些數(shù)據(jù)的報(bào)告，ORACLE提供profrep.sql腳本評(píng)估數(shù)據(jù)（在<oracle_home>/plsql/demo/目錄下）,下面的兩個(gè)簡(jiǎn)單腳本就是上面用到的，用來(lái)檢查程序單元的執(zhí)行時(shí)間.執(zhí)行時(shí)間以毫秒存儲(chǔ)
-----------------------------------------------------------
Script: call_profiler.sql
-----------------------------------------------------------
set head off
set pages 0
select decode(dbms_profiler.start_profiler, '0', 'Profiler started', 'Profiler error')
from dual;
--< place your routine in the below block >--
declare
l_status varchar2(200);
begin
am_perf_chk(2, l_status);
dbms_output.put_line(l_status);
end;
/
select decode(dbms_profiler.stop_profiler, '0', 'Profiler stopped', 'Profiler error')
from dual;
select decode(dbms_profiler.flush_data, '0', 'Profiler flushed', 'Profiler error')
from dual;
select 'runid:' plsql_profiler_runnumber.currval
from dual;
set head on
set pages 200
-----------------------------------------------------------
Script: evaluate_profiler_results.sql
-----------------------------------------------------------
undef runid
undef owner
undef name
set verify off
select s.line "Line", p.total_occur "Occur", p.total_time "Msec", s.text "Text"
from all_source s, (select u.unit_owner, u.unit_name, u.unit_type, d.line#,
d.total_occur, d.total_time/1000000 total_time
from plsql_profiler_data d, plsql_profiler_units u
where u.runid = &&runid
and u.runid = d.runid
and u.unit_number = d.unit_number) p
where s.owner = p.unit_owner (+)
and s.name = p.unit_name (+)
and s.type = p.unit_type (+)
and s.line = p.line# (+)
and s.name = upper('&&name')
and s.owner = upper('&&owner')
order by s.line;
select exec.cnt/total.cnt * 100 "Code% coverage"
from (select count(1) cnt
from plsql_profiler_data d, plsql_profiler_units u
where d.runid = &&runid
and u.runid = d.runid
and u.unit_number = d.unit_number
and u.unit_name = upper('&&name')
and u.unit_owner = upper('&&owner')) total,
(select count(1) cnt
from plsql_profiler_data d, plsql_profiler_units u
where d.runid = &&runid
and u.runid = d.runid
and u.unit_number = d.unit_number
and u.unit_name = upper('&&name')
and u.unit_owner = upper('&&owner')
and d.total_occur > 0) exec;
undef runid
undef owner
undef name
結(jié)論
DBMS_PROFILER是非常強(qiáng)大的工具，其一就是可以識(shí)別PL/SQL的性能問(wèn)題.這個(gè)工具最好用在開(kāi)發(fā)時(shí)期,用來(lái)調(diào)整基于各種應(yīng)用的情景的代碼，它也能用很好的調(diào)整已在使用中的例程并且采取顯而易見(jiàn)的時(shí)間去執(zhí)行。
總之，這個(gè)工具可以給每一行代碼給予性能統(tǒng)計(jì)，它可以幫助我們?cè)u(píng)估和調(diào)整到一個(gè)出色的水平,當(dāng)檢查SQL語(yǔ)句的性能問(wèn)題時(shí)，PL/SQL代碼不應(yīng)該忽略，相反應(yīng)該調(diào)整到最佳的結(jié)果.
