Re: procedures and transactions

On 2/19/19 12:31 PM, Rob Nikander wrote:
> Hi,
>
> I’m trying to understand how procedures work with transactions. I tried the code below - it’s a simple procedure to print some notices and commit a transaction. If I call it from psql after a `begin`, then it gives an error. What does that error mean? Are procedures not allowed to commit/rollback if they are called within in an outer transaction?
>
> Also, I tried putting a `start transaction` command in the procedure. I got another error: `unsupported transaction command in PL/pgSQL`. Are procedures not allowed to start transactions? Or is there another command?
>
> thanks,
> Rob
>
> create or replace procedure t_test(n integer)
> as $$
> begin
> raise notice 'current isolation level: %', (select current_setting('transaction_isolation'));
> raise notice 'current txid: %', (select txid_current());
> raise notice '---';
> commit;
> raise notice 'current isolation level: %', (select current_setting('transaction_isolation'));
> raise notice 'current txid: %', (select txid_current());
> end;
> $$ language plpgsql;
>
> psql> begin;
> psql> call t_test(1);

Don't use the begin;

call t_test(1);
NOTICE: current isolation level: read committed
NOTICE: current txid: 592
NOTICE: ---
NOTICE: current isolation level: read committed
NOTICE: current txid: 593
CALL

A function already starts in a transaction.

>
> NOTICE: current isolation level: read committed
> NOTICE: current txid: 111490
> NOTICE: ---
> ERROR: invalid transaction termination
>
>
>
>
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com