RE: Index question

[Johnson, Michael]

Terrista,   Did you run the UTLXPLAN.sql file so you can get a explain plan output ?    Check Metalink for an explanation of all of this .... here is one link ....   http://metalink.oracle.com/metalink/plsql/ml2_gui.startup   Then .....   SQL>  Set Autotrace on   Then  run those queries and report back the outputs.   Everything else is set up fine for now although we will probaly change a few more optimzer parameters so stay tuned for that.     buenos d�as a usted.  Miquel.   -----Original Message----- From: Teresita Castro [mailto:[EMAIL PROTECTED] Sent: Friday, June 27, 2003 10:30 AM To: Multiple recipients of list ORACLE-L Subject: RE: Index question About the  time test, this are some of the results:   SQL> set time on 10:22:59 SQL> select * from ictrans where item='0010096' 10:23:30   2  10:23:39 SQL> 10:23:53 SQL> select * from ictrans where location='TJU01' 10:24:20   2  10:24:21 SQL> update itemloc set average_cost=6.3 where company='2000' and item='0010041' 10:27:45   2  10:27:49 SQL> >>> [EMAIL PROTECTED] 06/26/03 03:09PM >>> Teresita,   Usted tiene un nombre hermoso.  Yo nunca he estado a Guadalajara, pero oigo es muy agradable. La mayor parte de mi tiempo en M�xico ha sido de Tiajuana completamente al sur a Zijuantinajo. El Pa�s hermoso y muy entibiar a gente Italia mucho m�s apreciando. Mi pr�ximo viaje a M�xico estar� a Cabo San Lucas probablemente en agosto. Espero llegar a Guadalajara alg�n d�a.   As for your current problem with the index......   First run a script called utlxplan.sql (spelling)  from the $ORACLE_HOME/rdbms/admin directory under the schema you wish to execute this query out of then     The  optimizer_mode = Choose   ,  timed_statistics = true  parameters can be set in your init*.ora file, but your can see the current setting of these values through ...   SQL>   select value from v$parameter where name like 'optimizer%'           or name = 'timed_statistics';   The query will also return several optimizer values which may be needed for assessment later on.        If you cannot bounce ( restart) the instance then consider setting these parameters using the command ...   SQL>  Alter session set .....   Then ....   SQL>  set autotrace traceonly also consider SQL>  set timing on for a relative cost on how much time the query takes   and then Execute your SQL statement which will output an  explain plan for your viewing pleasure.   Lots of information on metalink on how to use and interpret the explain plan.   Lets stop here and report back what your output is on the explain plan.   CAUTION:   I never use 3rd party products.   I like to go straight to the data dictionary to find out whats going on with the database.    Not to say 3rd party products are bad or anything, its just my style thats all.     Espero que esto lo ayude fuera.     Miquel.       -----Original Message----- From: Teresita Castro [mailto:[EMAIL PROTECTED] Sent: Thursday, June 26, 2003 11:25 AM To: Multiple recipients of list ORACLE-L Subject: RE: Index question 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 option:  optimizer_mode = Choose   timed_statistics = true   Michael: 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  "Usted habla ingl�s 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 default.   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 statement.   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.     Miquel.   -----Original Message----- From: Teresita Castro [mailto:[EMAIL PROTECTED] Sent: Wednesday, June 25, 2003 7:04 PM To: Multiple recipients of list ORACLE-L Subject: Re: Index question Hi!!   Let explain more about my situation. 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.   sQuery = "SELECT COMPANY,LOCATION, R_NAME FROM ICLOCATION " & _          "WHERE COMPANY=2000 OR COMPANY=2001 OR COMPANY=2002 order by COMPANY,LOCATION" Set recRS = New ADODB.Recordset recRS.Open sQuery, gcnOracle, adOpenForwardOnly, adLockReadOnly, adCmdText   or execute a delete or update statement   sSQL = "update  /*+ INDEX(itemloc ITLSET2) */ itemloc set average_cost =" & costo & " where (company='2000') and item= '" & Arti & "'" gcnOracle.Execute sSQL gcnOracle.Execute "Commit", dbSQLPassThrough    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 statement   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 friends!! >>> [EMAIL PROTECTED] 06/25/03 06:10PM >>> Teresita, I don't fully understand whether adding or removing a hint caused the problem but like Stephane said - you should probably stay away from them for now.  If adding a hint decreased performance then you have proved this for 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 when to use indexes or not automatically * Hints can force the optimisor to choose a non-optimal execution plan.  If you are smarter than the optimisor this may be fine but in most cases the optimisor will make the right decision when all tables are analyzed * Hints have very specific formatting and object name rules.  If you rename an index the hint will become invalid and be blissfully ignored - you won't even know. * There are some hints which can safely be used but it takes a good understanding of Oracle first.  My advice would be don't use them.  If you have a specific problem then post lot's of details here and someone might suggest trying a hint. * Until you really understand the implications of using a specific hint it can be dangerous in terms of performance - Stephane is not lying when he says 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 letting Oracle do what it does best. Regards,       Mark.                                                                                                                                                               "Teresita Castro"                                                                                                                       <[EMAIL PROTECTED]        To:       Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>                                        martmx.com>                cc:                                                                                                          Sent by:                   Subject:  Re: Index question                                                                                 [EMAIL PROTECTED]                                                                                                                     om                                                                                                                                                                                                                                                                                                                                                                                                                      26/06/2003 09:29                                                                                                                        Please respond to                                                                                                                       ORACLE-L                                                                                                                                                                                                                                                                                                                                                                                          Ophss...I have a terrible problem, I am using VB with Oracle and since we put that instruccion on the execute instruction our execution time decrease. The problem is that my boss was the one that found that instruction and I have to told her not to uses it, but with her I have to show some evidence that 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 harm than good. -- Regards, Stephane Faroult Oriole Software -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Stephane Faroult   INET: [EMAIL PROTECTED] Fat City Network Services    -- 858-538-5051 http://www.fatcity.com San Diego, California        -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from).  You may also send the HELP command for other information (like subscribing). <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<---->>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>    Privileged/Confidential information may be contained in this message.           If you are not the addressee indicated in this message        (or responsible for delivery of the message to such person),             you may not copy or deliver this message to anyone. 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