Unfortunately, this scheme only works if your only access is through the
Java layer to the RDBMS; any route which bypasses that (SQL*Plus or some
visual RDBMS data-manipulation tool) can easily break this system.
Another approach is to use a stored proc for your database that "somehow"
(table-locking, perhaps, or row-locking) returns a guaranteed-unique primary
key.
-----Original Message-----
From: Brian Long <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Friday, October 29, 1999 7:14 AM
Subject: Re: Question that is puzzling me
>depends - is the primary key a shared resource? usually for this kind of
thing it
>would be, so the answer in that case is no, you don't get threadsafety for
free.
>
>one simple way to ensure that you don't give out the same value to two (or
more)
>clients is to synchronize the method that you use to give out the keys:
>
>public synchronized int getNextKey(){
>
> return ++key;
>}
>
>which should ensure that you don't get two threads in there at once.
>
>hope this helps,
>-bml
>
>Nanduri Amarnath wrote:
>
>> Guys/Girls ,
>> I am calling a servlet from a jsp. The servlet implements the
>> SingleThreadModel.
>> The servlet has a doPost() method that writes data to a table in the
database.
>> The primary key
>> for each row of this Table is got by counting the ( number of rows in the
Table
>> + 1 ). This is done in the
>> doPost() method. Also i am setting autoCommit() to false ( in the
Connection
>> Object ) and doing either a
>> complete commit() or a complete rollback().
>>
>> My question is... if different people hit this page simultaneously, will
i still
>> be getting unique primary keys for every person
>> (or) if not is there a better way to do it......... Thanks in advance.
>>
>> Cheers,
>> Amar..
>>
>>
===========================================================================
>> To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff
JSP-INTEREST".
>> FAQs on JSP can be found at:
>> http://java.sun.com/products/jsp/faq.html
>> http://www.esperanto.org.nz/jsp/jspfaq.html
>
>--
>_________________________________________________________________________
>
>Brian M. Long RandomWalk Computing, Inc. [EMAIL PROTECTED]
>
>'Apollo was astonished / Dionysus thought me mad' -Hemispheres, 14:28
>__________________________________________________________________________
>
>===========================================================================
>To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff
JSP-INTEREST".
>FAQs on JSP can be found at:
> http://java.sun.com/products/jsp/faq.html
> http://www.esperanto.org.nz/jsp/jspfaq.html
===========================================================================
To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST".
FAQs on JSP can be found at:
http://java.sun.com/products/jsp/faq.html
http://www.esperanto.org.nz/jsp/jspfaq.html
