Re: How do BEGIN/COMMIT/ABORT operate in a nested SPI query?

David Bennett wrote:
> > From: Albe Laurenz [mailto:laurenz(dot)albe(at)wien(dot)gv(dot)at]
> >
> > > I am attempting to create a new language implementation. The language
> > > is Andl (andl.org) so the handler is plandl.
> > > This is a question about executing SPI queries from inside plandl.
> > >
> > > The documentation makes it clear that SPI allows nested queries; that
> > > in some instances it will be necessary to call SPI_push() and
> > > SPI_pop(), but in others this will be handled automatically. Se
> > http://www.postgresql.org/docs/9.5/interactive/spi-spi-push.html.
> > >
> > > It is an important design feature of plandl to allow nested queries.
> > >
> > > My question is: where are the transaction boundaries if the
> > > inner/outer query do or do not contain BEGIN/ABORT/COMMIT? Do they
> > > nest, or does an inner COMMIT finish a transaction started by an outer
> > BEGIN, or is it ignored?
> >
> > You cannot have BEGIN or COMMIT inside a function.
>
> Are you sure you meant it like that? I already have BEGIN/COMMIT inside a function and it works
> perfectly. If it did not, then it would be impossible to use BEGIN/COMMIT in any language handler,
> since every call to a language handler is a call to a function.
>
> Did you mean 'inside a nested function'? Or something else?

I guess I'm out of my depth when it comes to language handlers...

But I cannot see how you can have BEGIN or COMMIT called from inside one.

Doesn't it look like that:

BEGIN;
SELECT my_andl_function();
COMMIT;

Since there are no autonomous transactions in PostgreSQL, how can you have
BEGIN and COMMIT called from the code that is invoked by "SELECT my_andl_function()"?

Yours,
Laurenz Albe