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RE: SOME SOLUTIONS!

From: Gogala, Mladen <MGogala_at_oxhp.com>
Date: Thu, 08 Aug 2002 08:18:38 -0800
Message-ID: <F001.004AF275.20020808081838@fatcity.com>


Star schema will really, really help if you have bitmap indexes on your fact and details tables.  

Mladen Gogala
Oracle DBA
Phone: (203) 459-6855
Email: mgogala_at_oxhp.com

-----Original Message-----
Sent: Thursday, August 08, 2002 11:53 AM To: Multiple recipients of list ORACLE-L

Guys,

Any ideas why sum - with same exec. plan and not going to disk is 5 sec. response versus subsecond and anyway to get around this w/o building a preaggregated data set since there are so many permutations possible???? Will I have to redesign to use STAR SCHEMA and will that really help!!!

-----Original Message-----
Sent: Thursday, August 08, 2002 10:40 AM To: 'ORACLE-L_at_fatcity.com'

Okay,

Just going from #1 query to #2 query went from subsecond response to 6 secs. Not to mention for each sum it gets progressively worse!!!. The explain plan is exactly the same and I ran the sort query below and no rows returned.

rem truncate table plan_table;
set timing on;
rem explain plan set statement_id='RON' for select
/*+ INDEX(mv_birthstat,ndx_mvyr) */
 brth_mthr_res_newco_code County,count(*), -- sum(cert_chld_brth_year) Num1
 --sum(decode(greatest(cert_chld_brth_year,1996), least(cert_chld_brth_year,1998
), 1, 0)) / 3 Num2,
 --sum(decode(greatest(cert_chld_brth_year,1997), least(cert_chld_brth_year,1999
), 1, 0)) / 3 Num3
from mv_birthstat
where cert_chld_brth_year between '1995' and '1999'

and brth_mthr_res_state_code='10' 
and brth_mthr_age between 15 and 41 
group by brth_mthr_res_newco_code; 

/*+ INDEX(mv_birthstat,ndx_mvyr) */
 brth_mthr_res_newco_code County,
 sum(cert_chld_brth_year) Num1
 --sum(decode(greatest(cert_chld_brth_year,1996), least(cert_chld_brth_year,1998
), 1, 0)) / 3 Num2,
 --sum(decode(greatest(cert_chld_brth_year,1997), least(cert_chld_brth_year,1999
), 1, 0)) / 3 Num3
from mv_birthstat
where cert_chld_brth_year between '1995' and '1999'

and brth_mthr_res_state_code='10' 
and brth_mthr_age between 15 and 41 
group by brth_mthr_res_newco_code; 



WHY WHY WHY WHY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 
-----Original Message-----
<mailto:jack_silvey_at_yahoo.com> ]
Sent: Wednesday, August 07, 2002 11:37 PM To: Multiple recipients of list ORACLE-L

Paula,

Sorry to join this thread late, if I am rehashing just igonre.

I notice that your 'numbers' are surrounded by quotes, which will implicitly disable the index on those columns, perhaps the cause of the index hint. Are those columns text or numbers? If numbers, take out the quotes (and perhaps the hint) and rerun query.

Also, your aggregate functions will cause sorting - are you sorting to disk? See the query at the end of this to find out. If so, perhaps a larger sort_area_size and sort_area_retained_size might be in order.

Again, ignore if redundant.

Run this to look at sorting:

select t1.tablespace
, extents
, sum( t1.blocks * to_number( t3.value ) ) / 1024 /
1024 mb_used
, sum( t1.extents ) tot_extents
, t2.username
, t2.osuser
, t2.SID ||','|| t2.serial# SID_PID
, t4.spid
, t5.sql_text
, t1.segtype

from
v$sort_usage t1
,v$session t2
,v$parameter t3
,v$process t4
,v$sqlarea t5

where t1.SESSION_ADDR = t2.SADDR
and t3.name = 'db_block_size'
and (t2.PROCESS=t4.SPID or t2.paddr = t4.addr) and t2.sql_address=t5.address
and t2.status = 'ACTIVE'
group by
t1.tablespace
, t2.username
, t2.osuser
, t2.machine
, t2.schemaname
, t2.program
, t2.SID ||','|| t2.serial#
, t4.spid
, t5.sql_text
, t1.segtype
, segfile#
, extents

/

hth,

Jack

> ---- 
> | Operation                 |  Name    |  Rows | 
> Bytes|  Cost  | Pstart| 
> Pstop | 
> 
----------------------------------------------------------------------------

> ---- 
> | SELECT STATEMENT          |          |     1 |   
> 5 |   9331 |       | 
> | 
> |  SORT AGGREGATE           |          |     1 |   
> 5 |        |       | 
> | 
> |   SORT AGGREGATE          |          |     1 |   
> 5 |        |       | 
> | 
> |    INLIST ITERATOR        |          |       |    
>  |        |       | 
> | 
> |     PARTITION RANGE ITERAT|          |       |    
>  |        |KEY(I) 
> |KEY(I) | 
> |      BITMAP CONVERSION COU|          |       |    
>  |        |       | 
> | 
> |       BITMAP INDEX RANGE S|NDX_MVYRS |       |    
>  |        |KEY(I) 
> |KEY(I) | 
> 
> Cost higher but less than a second. 
> 
> Ignore the cost - higher cost was sign. 
> Faster!!!!!Does Key(*) mean it is 
> doing part. Elimin.  I think so but can you see the 
> inlist? 
> 
> Very fast with all years involved.  Then added 
> predicate: 
> 
> select 
> /*+ INDEX(mv_birthstat,ndx_mvyrstatecoage) */ 
> count(*) from mv_birthstat 
> where cert_chld_brth_year 
> in('1995','1996','1997','1998','1999') 
>    and brth_MTHR_res_STATE_CODE = '10'; 
> 
> - snails crawl by just adding the additional 
> column!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 
>

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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
<http://www.orafaq.com>  
-- 
Author: Jack Silvey 
  INET: jack_silvey_at_yahoo.com 

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-- 
Author: Gogala, Mladen
  INET: MGogala_at_oxhp.com

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San Diego, California        -- Public Internet access / Mailing Lists
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Received on Thu Aug 08 2002 - 11:18:38 CDT

Original text of this message

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