ibatis-user-java mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Larry Meadors" <lmead...@apache.org>
Subject Re: finding unique keys
Date Fri, 15 Sep 2006 15:03:27 GMT
+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
> > >>
> > >
> >
> >
> >
>
>

Mime
View raw message