Re: logicalrep_message_type throws an error

On Wed, Jul 5, 2023, at 7:56 AM, Alvaro Herrera wrote:
> On 2023-Jul-05, Amit Kapila wrote:
>
> > I think after returning "???" from logicalrep_message_type(), the
> > above is possible when we get the error: "invalid logical replication
> > message type "X"" from apply_dispatch(), right? If so, then what about
> > the case when we forgot to handle some message in
> > logicalrep_message_type() but handled it in apply_dispatch()? Isn't it
> > better to return the 'action' from the function
> > logicalrep_message_type() for unknown type? That way the information
> > could be a bit better and we can easily catch the code bug as well.
>
> Are you suggesting that logicalrep_message_type should include the
> numerical value of 'action' in the ??? message? Something like this:
>
> ERROR: invalid logical replication message type "X"
> CONTEXT: processing remote data for replication origin "pg_16638" during message type "??? (123)" in transaction 796, finished at 0/16266F8

Isn't this numerical value already exposed in the error message (X = 88)?
In this example, it is:

ERROR: invalid logical replication message type "X"
CONTEXT: processing remote data for replication origin "pg_16638" during message type "??? (88)" in transaction 796, finished at 0/1626698

IMO it could be confusing if we provide two representations of the same data (X
and 88). Since we already provide "X" I don't think we need "88". Another
option, is to remove "X" from apply_dispatch() and add "??? (88)" to
logicalrep_message_type().

Opinions?

--
Euler Taveira
EDB https://www.enterprisedb.com/