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From "Jeff Butler" <jeffgbut...@gmail.com>
Subject Re: finding unique keys
Date Fri, 15 Sep 2006 14:59:39 GMT
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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