Accessing query errors in a structured format.

[CrowdHailer]

A sample of the possible reasons a query with PGO might fail.

"null value in column \"thread_id\" violates not-null constraint"
"column \"zz\" does not exist"
"relation \"moo\" does not exist"
** (exit) exited in: :pgo_pool.checkout(:defaultzz, [])
 ** (EXIT) no process: the process is not alive or there's no process currently associated with the given name, possibly because its :"application isn't started"
{wrong_number_of_arguments,1,0}
{other,none_available} -> When the DB is down

Is there any level at which these errors are more structured. so that I can act on each type individually.

[tsloughter]

Pretty sure those first 3 are messages from postgres, right? So I don't think so. Unless there is a structured response for each error from postgres as part of the protocol, in which case we could have a structured response.

The other one is definitely wrong and needs to be updated.

[CrowdHailer]

I think the first ones are from postgres. Though I wondered if that was the message field and if there was more metadata. Postgres defines error codes and I also found this code in pgo that looked like it was decoding errors in a more strucutred manner.

https://github.com/erleans/pgo/blob/master/src/pgo_protocol.erl#L494-L514
i.e. can you get the constraint from the constraint field.

[tsloughter]

Definitely would be nice to have structured errors. I don't know about getting the constraint from the constraint field.