>> I still haven't seen anyone own up to analyzing SYS tables. Sure
seems like someone has.
We have one shop with gathered statistics on SYS schema.
Oracle EBS 11.5.7 + Patches
9.2.0.4 + 3 node RAC (Tru64 Alphas)
SYS:XXXX> select to_char(LAST_ANALYZED, 'YYYY/MM/DD') , count(*) from
dba_tables
SYS:XXXX> where owner = 'SYS'
SYS:XXXX> group by to_char(LAST_ANALYZED, 'YYYY/MM/DD')
SYS:XXXX> /
TO_CHAR(LA COUNT(*)
---------- ----------
2004/04/30 322
2004/07/25 1
29
SYS:XXXX>
There is no DD SQL perfomance problem in this env so far.
BTW: Compute stats is recuested in Apps env. Take a look on 245051.1
Jurijs
9268222
============================================
http://otn.oracle.com/ocm/jvelikanovs.html
----- Forwarded by Jurijs Veïikanovs/IT ALISE/LV on 30.07.2004 15:39 -----
J.Velikanovs@xxxxxxxx
Sent by: oracle-l-bounce@xxxxxxxxxxxxx
20.07.2004 18:03
Please respond to oracle-l
To: oracle-l@xxxxxxxxxxxxx
cc:
Subject: Re: No stats, why the heck is CBO running???
It is quite interesting, that Oracle require
to gather statistics on DD within Apps environment:
==========================
Metalink Note 216550.1
?Interoperability Notes Oracle Applications Release 11i
with Oracle9i Release 2 (9.2.0)?
step 18 Gather statistics for SYS schema
==========================
.
However doesn?t recommend in general:
==========================
Metalink Note 245051.1
?Gathering Data Dictionary Statistics?
Gathering statistics on the Data Dictionary in Oracle9i is a supported
activity.
In the majority of cases, gathering Data Dictionary statistics should not
be
necessary (and would not normally be recommended) since the dictionary
has been optimized to cater for most common database setups.
==========================
.
:)
Jurijs
9268222
============================================
http://otn.oracle.com/ocm/jvelikanovs.html
Tanel Põder <tanel.poder.003@xxxxxxx>
Sent by: oracle-l-bounce@xxxxxxxxxxxxx
20.07.2004 17:50
Please respond to oracle-l
To: <oracle-l@xxxxxxxxxxxxx>
cc:
Subject: Re: No stats, why the heck is CBO running???
> Yet a simple query to find the "next extext that wont fit" is always
using
the CBO???
>
> This SQL queries DBA_TABLES and DBA_FREE_SPACE. There are NO hints in
the
SQL.
>
> What the heck?
But there are hints in DBA_FREE_SPACE:
SQL> select text from dba_views where view_name = 'DBA_FREE_SPACE';
TEXT
----------------------------------------------------------------------------
----
select ts.name, fi.file#, f.block#,
f.length * ts.blocksize, f.length, f.file#
from sys.ts$ ts, sys.fet$ f, sys.file$ fi
where ts.ts# = f.ts#
and f.ts# = fi.ts#
and f.file# = fi.relfile#
and ts.bitmapped = 0
union all
select /*+ ordered use_nl(f) use_nl(fi) */
ts.name, fi.file#, f.ktfbfebno,
f.ktfbfeblks * ts.blocksize, f.ktfbfeblks, f.ktfbfefno
from sys.ts$ ts, sys.x$ktfbfe f, sys.file$ fi
where ts.ts# = f.ktfbfetsn
and f.ktfbfetsn = fi.ts#
and f.ktfbfefno = fi.relfile#
and ts.bitmapped <> 0 and ts.online$ in (1,4) and ts.contents$ = 0
These kind of issues are one of the reasons why one should avoid putting
hints inside views...
Now, when you join several unanalyzed tables with one analyzed one, CBO
will
be used by default and default statistics will be used for unanalyzed
tables
(or dynamic sampling depending on optimizer_dynamic_sampling parameter).
Tanel.
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