[erlang-questions] Application setup

Kirill Zaborski <>
Sat Jun 16 22:59:55 CEST 2007


Oh, I missed your point about {abprted,{already_exists,_}}
Thanks!

Regards,
Kirill.

On 6/16/07, Sean Hinde <> wrote:
>
> create_table will leave the table unchanged (including contents) if
> it already exists. In that way it behaves as a handy shorthand for
> checking whether the table exists and creating it if it does not.
>
> Sean
>
> On 16 Jun 2007, at 16:00, Kirill Zaborski wrote:
>
> > Seems reasonable but what if I stop application and then restart it
> > for some reason? I want to retain all the data that will be
> > collected in the application tables (some of them may be persistent).
> >
> > Regards,
> > Kirill
> >
> > On 6/16/07, Sean Hinde <> wrote:
> > On 16 Jun 2007, at 15:08, Kirill Zaborski wrote:
> >
> > > What is the recommended way to do application setup in OTP? I mean
> > > what if my application requires some initialization steps before
> > > running? E.g. it requires some mnesia tables created.
> > > As I understand for release upgrade I can do this using *.appup
> > > files in OTP Design Principles I see only example of process state
> > > modification is it OK to transform mnesia tables in code_change/3?
> > > And what do I when I install my application first time?
> >
> > I would suggest to define some record that all parts of your system
> > can use to define table definitions, then at system startup doing
> > something like:
> >
> > 1. Find the list of all table definition records.
> > 2. Attempt to create all tables.
> > 3. Any that are already created (return {aborted,{already_exists,_}})
> > compare the fields and if different do a table transform.
> >
> > This way you not only get the tables created at startup, but you also
> > get auto upgrade.
> >
> > You could do this during startup of one of your first applications.
> >
> > Sean
> >
> >
>
>
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