Re: psql - add special variable to reflect the last query status

2017-05-22 9:40 GMT+02:00 Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>:

>
> Hello Pavel,
>
> After some discussions about what could be useful since psql scripts now
>>>> accepts tests, this patch sets a few variables which can be used by psql
>>>> after a "front door" (i.e. actually typed by the user) query:
>>>>
>>>> - RESULT_STATUS: the status of the query
>>>> - ERROR: whether the query failed
>>>> - ERROR_MESSAGE: ...
>>>> - ROW_COUNT: #rows affected
>>>>
>>>> SELECT * FROM ;
>>>> \if :ERROR
>>>> \echo oops
>>>> \q
>>>> \endif
>>>>
>>>> I'm not sure that the names are right. Maybe STATUS would be better than
>>>> RESULT_STATUS.
>>>>
>>>
>>> I am sending review of this patch:
>>
>> 1. I agree so STATUS is better name, than RESULT status.
>>
>
> Ok, looks simpler.
>
> Currently it returns values with prefix PGRES (like PGRES_FATAL_ERROR,
>> PGRES_TUPLES_OK). Maybe we should to cut this prefix. FATAL_ERROR,
>> TUPLES_OK looks better for custom level. The PGRES prefix has not sense in
>> psql.
>>
>
> Indeed. I skipped "PGRES_".
>
> 2. I propose availability to read ERROR_CODE - sometimes it can be more
>> practical than parsing error possible translated message
>>
>
> Ok.
>
> 3. The fields ERROR_MESSAGE and ROW_COUNT are set only when it has sense.
>> This behave is maybe too strict for psql and the processing needs more
>> nesting \if command. What do you think about -1 or 0 for ROW_COUNT (for
>> DDL) and "" for ERROR_MESSAGE when there are not any error? It will be
>> consistent with already implemented LASTOID variable (and other state psql
>> variables). Using default values are not strict clean, but it can reduce
>> complexity of psql scripts.
>>
>
> My intention was that it could be tested with the "is defined" syntax,
> which is yet to be agreed upon and implemented, so maybe generating empty
> string is a better option.
>
> For ROW_COUNT, I think that it should be consistent with what PL/pgSQL
> does, so it think that 0 should be the default.
>
> 4. all regress tests passed
>> 5. there are not any problem with doc building
>>
>
> Please find attached a v2 which hopefully takes into account all your
> points above.
>
> Open question: should it gather more PQerrorResultField, or the two
> selected one are enough? If more, which should be included?

I don't think so it is necessary. No in this moment. ERROR_CODE and
ERROR_MESSAGE are fundamental - and if we add other, then we should to add
all. Has not sense to add only some.

Regards

Pavel

>
> --
> Fabien.