Re: How to watch for schema changes - Mailing list pgsql-general

Hi, Adrian,

On Mon, Dec 3, 2018 at 5:15 PM Adrian Klaver <adrian.klaver@aklaver.com> wrote:
>
> On 12/3/18 3:00 PM, Igor Korot wrote:
> > Hi, Adrian,
> >
> > On Mon, Dec 3, 2018 at 4:10 PM Adrian Klaver <adrian.klaver@aklaver.com> wrote:
> >>
> >> On 12/3/18 1:53 PM, Igor Korot wrote:
> >>> Hi, Adrian,
> >>
> >>>> Why? Just create the trigger once in a script. Event triggers are an
> >>>> attribute of the database and stay with it until they are dropped. If
> >>>> you want to turn then on and off use the ALTER  EVENT TRIGGER
> >>>> ENABLE/DISABLE. If you insist on recreating them on each connection then:
> >>>>
> >>>> https://www.postgresql.org/docs/10/sql-dropeventtrigger.html
> >>>> DROP EVENT TRIGGER [ IF EXISTS ] name [ CASCADE | RESTRICT ]
> >>>> CREATE EVENT TRIGGER ...
> >>>
> >>> I was hoping to create a software which will be just "install-and-use".
> >>> No additional script running or database changes is required.
> >>
> >> After I hit reply my subconscious kicked in and pointed out something:)
> >>
> >> If there are no database changes why do you need to track schema changes?
> >
> > That was a bad word selection. ;-)
> >
> > What I mean to say was "no schema changes/server changes that comes
> > independently
> > of the program install". Or something to that extent.
>
> Which circles back around to the same question:
>
> If there are to be no schema changes after the install why track them on
> subsequent connections?
>
> Or maybe an explanation of what you are trying to achieve would make
> things clearer?

Ok, it probably will make things clearer.
So I install my program perform some queries and exit.
At the same time if the user will create or delete a table the program should
pick up those changes and act accordingly.

I was hoping to do the watching initialization dynamically, but it looks as it
is more pain and I can probably try to execute the script during the
installation.

So basically I will create the function in C, compile it and then
during the program installation
create a trigger with that function.
Then in my program I will execute "LISTEN" command and act accordingly.

Am I right?

And executing LISTEN will also work for ODBC connection, right?

Thank you.

>
>
>
> >
> > Sorry, ESL person here.
> >
> > Thank you.
> >
> >>
> >>>
> >>> But I will probably create it on every connection and delete on the
> >>> disconnect (see above).
> >>>
> >>
> >> --
> >> Adrian Klaver
> >> adrian.klaver@aklaver.com
> >
>
>
> --
> Adrian Klaver
> adrian.klaver@aklaver.com