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以sys登录进行授权 grant select on sys.v_$timer to suk; grant select on v_$mystat to suk; grant select on sys.v_$statname to suk; grant select on sys.v_$latch to suk;
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This is the test harness I use to try out different ideas. It shows two vital sets of statistics for me
The elapsed time difference between two approaches. It very simply shows me which approach is faster by the wall clock
How many resources each approach takes. This can be more meaningful then even the wall clock timings. For example, if one approach is faster then the other but it takes thousands of latches (locks), I might avoid it simply because it will not scale as well.
The way this test harness works is by saving the system statistics and latch information into a temporary table. We then run a test and take another snapshot. We run the second test and take yet another snapshot. Now we can show the amount of resources used by approach 1 and approach 2.
Requirements
In order to run this test harness you must at a minimum have:
Access to V$STATNAME, V$MYSTAT, v$TIMER and V$LATCH
You must be granted select DIRECTLY on SYS.V_$STATNAME, SYS.V_$MYSTAT, SYS.V_$TIMER and SYS.V_$LATCH. It will not work to have select on these via a ROLE.
The ability to create a table -- run_stats -- to hold the before, during and after information.
The ability to create a package -- rs_pkg -- the statistics collection/reporting piece
You should note also that the LATCH information is collected on a SYSTEM WIDE basis. If you run this on a multi-user system, the latch information may be technically "incorrect" as you will count the latching information for other sessions - not just your session. This test harness works best in a simple, controlled test environment.
The table we need is very simple:
create global temporary table run_stats
( runid varchar2(15),
name varchar2(80),
value int )
on commit preserve rows;
then you can create this view:
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;
Now the test harness package itself is very simple. Here it is:
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;
/
/*
exec runStats_pkg.rs_start;
exec runStats_pkg.rs_middle;
exec runStats_pkg.rs_stop;
*/
