效能比較工具runStats_pkg

runStats_pkg是Tom大師寫的一個指令碼,
用於比較兩個語句的時間,統計資料和栓鎖使用情況。
指令碼下載連結:
https://asktom.oracle.com/pls/asktom/ASKTOM.download_file?p_file=6551378329289980701

下面以edmond帳號為例，使用runStats比較繫結變數的差異

首先,給edmond帳號系統表的授權。
conn / as sysdba
create user edmond identified by edmond;
grant connect,resource to edmond;
grant create view to edmond;
grant select on sys.v_$statname to edmond;
grant select on sys.v_$mystat to edmond;
grant select on sys.v_$latch to edmond;
grant select on sys.v_$timer to edmond;

然後,執行runStats指令碼

create global temporary table run_stats
( runid varchar2(15),
name varchar2(80),
value int )
on commit preserve rows;
create or replace view stats
as select 'STAT...' || a.name name, b.value
from sys.v_$statname a, sys.v_$mystat b
where a.statistic# = b.statistic#
union all
select 'LATCH.' || name, gets
from sys.v_$latch
union all
select 'STAT...Elapsed Time', hsecs from sys.v_$timer;
create or replace package runstats_pkg
as
procedure rs_start;
procedure rs_middle;
procedure rs_stop( p_difference_threshold in number default 0 );
end;
/
create or replace package body runstats_pkg
as
g_start number;
g_run1 number;
g_run2 number;
procedure rs_start
is
begin
delete from run_stats;
insert into run_stats
select 'before', stats.* from stats;
g_start := dbms_utility.get_cpu_time;
end;
procedure rs_middle
is
begin
g_run1 := (dbms_utility.get_cpu_time-g_start);
insert into run_stats
select 'after 1', stats.* from stats;
g_start := dbms_utility.get_cpu_time;
end;
procedure rs_stop(p_difference_threshold in number default 0)
is
begin
g_run2 := (dbms_utility.get_cpu_time-g_start);
dbms_output.put_line
( 'Run1 ran in ' || g_run1 || ' cpu hsecs' );
dbms_output.put_line
( 'Run2 ran in ' || g_run2 || ' cpu hsecs' );
if ( g_run2 <> 0 )
then
dbms_output.put_line
( 'run 1 ran in ' || round(g_run1/g_run2*100,2) ||
'% of the time' );
end if;
dbms_output.put_line( chr(9) );
insert into run_stats
select 'after 2', stats.* from stats;
dbms_output.put_line
( rpad( 'Name', 30 ) || lpad( 'Run1', 12 ) ||
lpad( 'Run2', 12 ) || lpad( 'Diff', 12 ) );
for x in
( select rpad( a.name, 30 ) ||
to_char( b.value-a.value, '999,999,999' ) ||
to_char( c.value-b.value, '999,999,999' ) ||
to_char( ( (c.value-b.value)-(b.value-a.value)), '999,999,999' ) data
from run_stats a, run_stats b, run_stats c
where a.name = b.name
and b.name = c.name
and a.runid = 'before'
and b.runid = 'after 1'
and c.runid = 'after 2'
-- and (c.value-a.value) > 0
and abs( (c.value-b.value) - (b.value-a.value) )
> p_difference_threshold
order by abs( (c.value-b.value)-(b.value-a.value))
) loop
dbms_output.put_line( x.data );
end loop;
dbms_output.put_line( chr(9) );
dbms_output.put_line
( 'Run1 latches total versus runs -- difference and pct' );
dbms_output.put_line
( lpad( 'Run1', 12 ) || lpad( 'Run2', 12 ) ||
lpad( 'Diff', 12 ) || lpad( 'Pct', 10 ) );
for x in
( select to_char( run1, '999,999,999' ) ||
to_char( run2, '999,999,999' ) ||
to_char( diff, '999,999,999' ) ||
to_char( round( run1/decode( run2, 0, to_number(null), run2) *100,2 ), '99,999.99' ) || '%' data
from ( select sum(b.value-a.value) run1, sum(c.value-b.value) run2,
sum( (c.value-b.value)-(b.value-a.value)) diff
from run_stats a, run_stats b, run_stats c
where a.name = b.name
and b.name = c.name
and a.runid = 'before'
and b.runid = 'after 1'
and c.runid = 'after 2'
and a.name like 'LATCH%'
)
) loop
dbms_output.put_line( x.data );
end loop;
end;
end;
/

接下來建立測試表和過程
create table t(x int);
insert into t select rownum from dual connect by level<=10000;

沒有繫結變數的測試過程
create or replace procedure p1
as
    l_cnt number;
begin
    for i in 1 .. 10000
    loop
        execute immediate 'select count(*) from t where x=' || i into l_cnt;
    end loop;
end;
/

繫結變數的測試過程
create or replace procedure p2
as
    l_cnt number;
begin
    for i in 1 .. 10000
    loop
        select count(*) into l_cnt from t where x=i;
    end loop;
end;
/

開始測試:
set serveroutput on;
alter system flush shared_pool;

exec runStats_pkg.rs_start;
exec p1;
exec runStats_pkg.rs_middle;
exec p2;
exec runStats_pkg.rs_stop(1000);

測試結果
可以看到第一個過程解析了近1w次,而第二個過程僅僅解析了7次
非繫結變數的方式導致了大量的栓鎖使用.

來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/29254281/viewspace-1273911/，如需轉載，請註明出處，否則將追究法律責任。

效能比較工具runStats_pkg

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