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Re[2]: What's lock/unlock mechnism

From: <dgoulet_at_vicr.com>
Date: Fri, 29 Jun 2001 06:39:42 -0700
Message-ID: <F001.0033D66A.20010629063055@fatcity.com> 






One can influence the locking of data via the "lock table" command and "for
update of" portions of a SQL cursor.  As a general rule of thumb I totally
discourage anyone from ever using the lock table command.  Certainly the process
within the server is complicated as needs be, but it is one of the best I've
seen in terms of concurrency and consistency.  If your having a problem with
clients being able to access data that is locked by another client then the
problem is either in their application and/or their use of the application. 
I've seen problems where a user updated a number of records in SQL*Plus and then
decided to go to lunch while the statement completed.  A second user then tried
to update a different column in a number of the same records only to get "locked
out".  The answer was to have a few words with the first users manager, who BTW
was the second user's manager as well.  From then on this individual never left
a statement just to run by itself & the problem has not re-occurred.  In general
locking issues are VERY infrequently a server side problem though that is where
it is implemented.  Instead they are almost always a client side issue.  Also,
there is no way that I can think of for a client to manage their locks without
involving the server.



Dick Goulet


____________________Reply Separator____________________
Author: nlzanen1_at_EY.NL
Date:       6/29/2001 2:01 AM






Hi,




To find out more about the locking mechanism you can try the oracle
concepts manual



Jack



                                                                                
                                 
                    Helen rwulfjeq                                              
                                
                    <lannyue_at_yahoo       To:     Multiple recipients of list
ORACLE-L <ORACLE-L_at_fatcity.com>     
                    .com>                cc:     (bcc: Jack van
Zanen/nlzanen1/External/MEY/NL)                  
                    Sent by:             Subject:     Re: What's lock/unlock
mechnism                            
                    root_at_fatcity.c                                              
                                
                    om                                                          
                                
                                                                                
                                 
                                                                                
                                 
                    28-06-2001                                                  
                                
                    21:40                                                       
                                
                    Please respond                                              
                                
                    to ORACLE-L                                                 
                                
                                                                                
                                 
                                                                                
                                 







Thank you very much for your response. But how oracle design let server to
handle locks. There are lots of overheads because lots of clients can
access server at a same time. If client handles individually, They will
release lots of overburden for server. And server just make sure that only
owner of lock can unlock CS. Anywhere we can find those information.




Thanks.




HL




  nlzanen1_at_EY.NL wrote:



 Hi,




 All locking is handled by the server, not client




 Jack





 Helen rwulfjeq



 .com> cc: (bcc: Jack van Zanen/nlzanen1/External/MEY/NL)
 Sent by: Subject: What's lock/unlock mechnism
 root_at_fatcity.c


 om




 28-06-2001


 00:09


 Please respond


 to ORACLE-L







 Hi ,







 Oracle database system uses very complicated lock/unlock design for
 readlock,writelock and row/recordlock etc..... Does anyone know
 lock/unlock


 is implemented both client like sqlplus and server side or just on server
 side or just client side. For instance, one user using sqlplus access
 database to update one record of table XX. So should be sqlplus's
 responsibility to lock this record based on row level of XX table? or
 serve! ! ! r is also involved in? Thanks.




 H.





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algemene voorwaarden worden u op verzoek kosteloos toegezonden.




The information contained in this communication is confidential and is
intended solely for the use of the individual or entity to whom it is
addressed. You should not copy, disclose or distribute this communication
without the authority of Ernst & Young. Ernst & Young is neither liable for
the proper and complete transmission of the information contained in this
communication nor for any delay in its receipt. Ernst & Young does not
guarantee that the integrity of this communication has been maintained nor
that the communication is free of viruses, interceptions or interference.



If you are not the intended recipient of this communication please return
the communication to the sender and delete and destroy all copies.



In carrying out its engagements, Ernst & Young applies general terms and
conditions, which contain a clause that limits its liability. A copy of
these terms and conditions is available on request free of charge.








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Author: 
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Received on Fri Jun 29 2001 - 08:39:42 CDT












Original text of this message













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