From Teresita.Castro@s-martmx.com Thu, 26 Jun 2003 10:42:26 -0700 From: "Teresita Castro" Date: Thu, 26 Jun 2003 10:42:26 -0700 Subject: RE: Index question Message-ID: MIME-Version: 1.0 Content-Type: text/plain 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 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 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 PMTo: Multiple recipients of list ORACLE-LSubject: 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.RecordsetrecRS.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 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 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 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: http://www.orafaq.net--Author: Stephane Faroult  INET: [EMAIL PROTECTED]Fat City Network Services    -- 858-538-5051 http://www.fatcity.comSan Diego, California        -- Mailing list and web hosting services---------------------------------------------------------------------To REMOVE yourself from this mailing list, send an E-Mail messageto: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and inthe message BODY, include a line containing: UNSUB ORACLE-L(or the name of mailing list you want to be removed from).  You mayalso 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.In such case, you should destroy this message and kindly notify the sender           by reply e-mail or by telephone on (61 3) 9612-6999.   Please advise immediately if you or your employer does not consent to                Internet e-mail for messages of this kind.        Opinions, conclusions and other information in this message              that do not relate to the official business of                         Transurban City Link Ltd         shall be understood as neither given nor endorsed by it.<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<---->>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>-- Please see the official ORACLE-L FAQ: http://www.orafaq.net-- Author: Mark Richard  INET: [EMAIL PROTECTED]Fat City Network Services    -- 858-538-5051 http://www.fatcity.comSan Diego, California        -- Mailing list and web hosting services---------------------------------------------------------------------To REMOVE yourself from this mailing list, send an E-Mail messageto: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and inthe message BODY, include a line containing: UNSUB ORACLE-L(or the name of mailing list you want to be removed from).  You mayalso send the HELP command for other information (like subscribing).