性能比较工具runstats

runstats能对做同一件事的两个不同方法进行比较，得出谁好一点。我们只需要提供两个不同方法，余下的事情都由runstats负责。runstats只是测量3个要素：

1. 耗用的时间。

2. 系统统计结果：会并排地显示每个方法做某件事(如执行一个解析调用)的次数，并展示二者之差。

3. latching,这是报告关键的输出。

安装过程：

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 v$statname a, v$mystat b
where a.statistic# = b.statistic#
union all
  select 'LATCH.' || name, gets from v$latch
union all
  select 'STAT...Elapsed Time', hsecs from v$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_time;
end;
procedure rs_middle
is
begin
  g_run1 := (dbms_utility.get_time-g_start);
  insert into run_stats  select 'after 1', stats.* from stats;
  g_start := dbms_utility.get_time;
end;
procedure rs_stop(p_difference_threshold in number default 0)
is
begin
 g_run2 := (dbms_utility.get_time-g_start);
 dbms_output.put_line
 ( 'Run1 ran in ' || g_run1 || ' hsecs' );
 dbms_output.put_line
 ( 'Run2 ran in ' || g_run2 || ' 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 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(0), 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;
/