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RE: Index question

From: Teresita Castro <>
Date: Thu, 26 Jun 2003 10:42:26 -0700
Message-ID: <>

Where I can see the explain Plan?... I have TOAD but is a try version and I don't have this option activated,  can I see it in another program?

And where I have to define this
<FONT color=#000080
size=2> optimizer_mode = Choose 
size=2> timed_statistics = true
<FONT color=#000080
Sobre tus vacaciones como estaras cerca de Guadalaja, te recomiendo visitar estar ciudad, y  tomar el tur del tren Tequita express. Yo no he ido a puerto Vallarte pero la gente de por alla es muy amigable y servicial, buena suerte !!
>>> [EMAIL PROTECTED] 06/25/03 09:59PM
First, Your english is
excellent or  <FONT
size=1>"Usted habla inglés muy bien. "

Assuming you are running
version 8i or better ....

Have you analyzed the tables
you are querying against ?  You may not need to force a rule as the CBO will
try to find the quickest way.   It looks like you are using the RBO by

Do you have optimizer_mode =
Choose  ?
Do you have timed_statistics =
true ?

Have you run your queries
through an explain plan ?  If not this will show you the execution path and
a relative cost of each statement.
You can manipulate your SQL to
see different costs as you change the

Also,  Your queries could
have been run while competing for resources in one case and maybe not in
another case.  Run both queries in the same environment. 


I have found that small tables
don't need indexes for the most part although this is not a hard and fast
rule.   You must go through the process.
 Espero que eso lo ayude y

la buena suerte a usted.   Espero verlo en Puerto Vallarta Alguna Vez
pronto en la playa con un margarita. Hasta Luego.  



  Message-----From: Teresita Castro
  [mailto:[EMAIL PROTECTED]Sent: Wednesday, June 25, 2003   7:04 PMTo: Multiple recipients of list ORACLE-LSubject:   Re: Index question
  Let explain more about my
  The company that I work for is a
  chain of stores around some city's on Mexico, they bought Lawson a system that   uses Oracle to manage the data bases, at first they use SQL Server 2000, but I   wasn't enough to manager all the information.   The structure of the table is all ready done   and I have to learn it to do some reports that Lawson don't have, change or   delete information and export some information to dbf files. Because we   was using SQL Server I used Store procedures to return  the select   result to VB recordset and the I pass the select result to Crystal Report   or to a DBF file.
  Well  I see that in Oracle the store
  procedure do not returns the result set has easy has SQL Server so I use and   statement that after execute it returns me the result in a record   set.
  _         "WHERE COMPANY=2000 OR
  COMPANY=2001 OR COMPANY=2002 order by COMPANY,LOCATION"Set recRS = New   ADODB.RecordsetrecRS.Open sQuery, gcnOracle, adOpenForwardOnly,   adLockReadOnly, adCmdText
  or execute a delete or update
  sSQL = "update  /*+ INDEX(itemloc
  ITLSET2) */ itemloc set average_cost =" & costo & " where   (company='2000') and item= '" & Arti & "'"gcnOracle.Execute   sSQL
  gcnOracle.Execute "Commit",
  Back to my problem:
  In this case the update of the average cost   has to be done on the table Item location ( ITEMLOC)  that have all the   item that each location( store) have. The locations have a company, when   we changes the average cost is per company ( each company represent a   different city) 
  So my boss  execute the update

  sSQL = "update  itemloc set
  average_cost =" & costo & " where (company='2000') and item= '" &   Arti & "'"
  and she told me that per item  it
  takes like 10 seconds.
  After read the article that I mention   she changes the statement to this :
   sSQL = "update  /*+
  INDEX(itemloc ITLSET2) */ itemloc set average_cost =" & costo & "   where (company='2000') and item= '" & Arti & "'"    
  ITLSET2 is a index that have company(1),   location(2) and Item(3) and it takes 2   seconds per item, so that is way she is convinced that we have to uses the   /*+ INDEX(itemloc ITLSET2) */ in all of our select, update or   delete statement.
  I hope you undestant my English and my problem   too, because I have to do some really complicated queries that have   like 3 or 5 tables in them, and using this method will give me some   serious complications, maybe in this case (change of the average cost) is not   too dangerous. 
  But I have to give her strong statements   to change her mind.
  Thanks for everything
  >>> [EMAIL PROTECTED] 06/25/03 06:10PM   >>>Teresita,I don't fully understand whether adding   or removing a hint caused theproblem but like Stephane said - you should   probably stay away from themfor now.  If adding a hint decreased   performance then you have proved thisfor yourself.A couple of   important points:* Using an index isn't always faster than scanning   the table* If a database is correctly analyzed then the optimisor can   determine whento use indexes or not automatically* Hints can force   the optimisor to choose a non-optimal execution plan.  Ifyou are   smarter than the optimisor this may be fine but in most cases theoptimisor   will make the right decision when all tables are analyzed* Hints have   very specific formatting and object name rules.  If you renamean   index the hint will become invalid and be blissfully ignored - you   won'teven know.* There are some hints which can safely be used but   it takes a goodunderstanding of Oracle first.  My advice would be   don't use them.  If youhave a specific problem then post lot's of   details here and someone mightsuggest trying a hint.* Until you   really understand the implications of using a specific hint itcan be   dangerous in terms of performance - Stephane is not lying when hesays you   can do more harm than good.  I have many cases where I can "tune"a   query simply by removing the hints which someone included and   lettingOracle do what it does



  To:       Multiple recipients of list ORACLE-L
  <[EMAIL PROTECTED]>                  

  Subject:  Re: Index 
  [EMAIL PROTECTED]                                                                                               


  Please respond
  Ophss...I have a terrible problem, I am using VB with   Oracle and since weput that instruccion on the execute instruction our   execution timedecrease.The problem is that my boss was the one   that found that instruction and Ihave to told her not to uses it, but with   her I have to show some evidencethat show why now to uses hits.Do   you have any information that I can show to   her.Thanks!!!>>> [EMAIL PROTECTED] 06/25/03 02:34PM   >>>Teresita,   Since you advertise yourself as   a newbie, listen to an old-timer :for the next two years, forget about   hints. You risk doing more harmthan
  good.--Regards,Stephane FaroultOriole   Software--Please see the official ORACLE-L FAQ: <A   href="">   Stephane Faroult  INET: [EMAIL PROTECTED]Fat City Network   Services    -- 858-538-5051 <A
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subscribing). Received on Thu Jun 26 2003 - 12:42:26 CDT

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