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From "Edwin Lukaweski" <serj...@rogers.com>
Subject Re: finding unique keys
Date Fri, 15 Sep 2006 16:14:34 GMT
Great!

    Now....I guess when the insert fails, via iBatis and an SQL_Map, I will get an SQLExceptiion.
Is there an easy way to find the -803?

    I want to intercept it and re-throw only non 803 exceptions.

thanks,
Edwin

  ----- Original Message ----- 
  From: Jeff Butler 
  To: user-java@ibatis.apache.org 
  Sent: Friday, September 15, 2006 12:08 PM
  Subject: Re: finding unique keys


  I just looked to see how Spring does it with DB2.  They do look for -803 as the error code
from the SqlException.  So I think your plan sounds good.

  Jeff Butler


   
  On 9/15/06, Edwin Lukaweski <serjann@rogers.com> wrote: 
    Thanks for all the feed back!!!

    Some answers:

       1) I am using DB2 for z/OS version 7

       2) Yes, UUID's are by definition 'universally unique', excpept whe two
    are gengerated, say by two different JVMs,  within the same millisecond.
    The, they turn out to be duplicates.

       3) I like the idea of doing an optimistic INSERT. I have always had 
    trouble figuring which sql code to look for that represents this situation.
    As best I can tell, it is SQLCODE 803. So, if I see this code in an
    exception, loop again, otherwise throw a real sqlexception.

    What do you think?

    thanks,
    Edwin

    ----- Original Message -----
    From: "Larry Meadors" <lmeadors@apache.org>
    To: < user-java@ibatis.apache.org>
    Sent: Friday, September 15, 2006 11:03 AM
    Subject: Re: finding unique keys


    > +1 ;-)
    >
    > Larry
    >
    >
    > On 9/15/06, Jeff Butler < jeffgbutler@gmail.com> wrote:
    >>
    >> Some thoughts...
    >>
    >> 1. Aren't UUID's "universally unique" by definition?  Are you sure you
    >> need
    >> to do this? 
    >>
    >> 2. Table locking is almost always a bad idea.  I had a similar situation
    >> to
    >> yours in that past, and decided to take the optomistic route, meaning...
    >>
    >> - generate the key 
    >> - insert the record
    >> - if the insert blows because of a duplicate key, then generate a new key
    >> and try again
    >>
    >> Since the likelihood of generating a duplicate UUID should be very low, 
    >> this
    >> approcah will work in the vast majority of cases.
    >>
    >>
    >> Jeff Butler
    >>
    >>
    >>
    >>
    >> On 9/15/06, Edwin Lukaweski < serjann@rogers.com> wrote:
    >> > Thanks for the answer.
    >> >
    >> >    I am stuck with an existing table definition, in a schema, that I
    >> cannot
    >> > modify at this point due to being in production. 
    >> >
    >> >    So, this is the best method I can come up with.
    >> >
    >> >    also....now you have tweaked my curiosity. In addition to the advice
    >> > I
    >> > am seeking, it I could alter the table definition to use some form of 
    >> > auto-increment, how would I retrieve the generated value in iBatis?
    >> >
    >> >    So.....I now have two questions.
    >> >
    >> > thanks,
    >> > Ediwn
    >> >
    >> > ----- Original Message -----
    >> > From: "Larry Meadors" < lmeadors@apache.org>
    >> > To: < user-java@ibatis.apache.org>
    >> > Sent: Friday, September 15, 2006 10:14 AM
    >> > Subject: Re: finding unique keys
    >> >
    >> >
    >> > > One question: Why not just let the database do it and have it tell

    >> > > you
    >> > > the generated key?
    >> > >
    >> > > Larry
    >> > >
    >> > >
    >> > > On 9/15/06, Edwin Lukaweski < serjann@rogers.com> wrote:
    >> > >>
    >> > >>
    >> > >> Hi:
    >> > >>
    >> > >>     I have a situation for which I need some advice while using

    >> > >> iBatis.
    >> > >>
    >> > >>     What I would like to do is:
    >> > >>
    >> > >>     1) generate a unique UUID style value in my Java program 
    >> > >>
    >> > >>     2) lock a table, say tabxx
    >> > >>
    >> > >>     3) SELECT on the table to see if the UUID exists as a key
    >> > >> 
    >> > >>     4) if so, add 1 to the key and go to step 3
    >> > >>
    >> > >>     5) if the key does NOT exist, insert the record
    >> > >>
    >> > >>     6) unlock the table 
    >> > >>
    >> > >>     Can anyone get me advice as to how to do this with iBatis?
    >> > >>
    >> > >> Thanks, very musch, in advance
    >> > >> 
    >> > >> Edwin
    >> > >>
    >> > >
    >> >
    >> >
    >> >
    >>
    >>
    >





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