Re: is ErrorResponse possible on Sync?

I used your example and tried it with prepared statements. I captured the
traffic with
Wireshark. My client sent Bind/Execute/Sync messages, and PostgreSQL 14 sent
back BindComplete/CommandComplete/ErrorResponse messages, followed by
ReadyForQuery after that.

So yes, it looks like ErrorResponse is a valid response for Sync.

On Tue, Jan 18, 2022 at 6:11 PM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
wrote:

> On 2022-Jan-12, Andrei Matei wrote:
>
> > If Sync itself cannot fail, then what is this
> > sentence really saying: "This parameterless message (ed. Sync) causes the
> > backend to close the current transaction if it's not inside a
> BEGIN/COMMIT
> > transaction block (“close” meaning to commit if no error, or roll back if
> > error)." ?
> > This seems to say that, outside of BEGIN/END, the transaction is
> committed
> > at Sync time (i.e. if the Sync is never sent, nothing is committed).
> > Presumably, committing a transaction can fail even if no
> > previous command/statement failed, right?
>
> A deferred trigger can cause a failure at COMMIT time for which no
> previous error was reported.
>
> alvherre=# create table t (a int unique deferrable initially deferred);
> CREATE TABLE
> alvherre=# insert into t values (1);
> INSERT 0 1
> alvherre=# begin;
> BEGIN
> alvherre=*# insert into t values (1);
> INSERT 0 1
> alvherre=*# commit;
> ERROR: duplicate key value violates unique constraint "t_a_key"
> DETALLE: Key (a)=(1) already exists.
>
> I'm not sure if you can cause this to explode with just a Sync message,
> though.
>
> --
> Álvaro Herrera Valdivia, Chile —
> https://www.EnterpriseDB.com/
>
>
>
>
>