Re: pg_stat_progress_basebackup - progress reporting for pg_basebackup, in the server side

On 2020/03/19 11:32, Amit Langote wrote:
> On Thu, Mar 19, 2020 at 11:24 AM Alvaro Herrera
> <alvherre(at)2ndquadrant(dot)com> wrote:
>> On 2020-Mar-19, Amit Langote wrote:
>>
>>> Magnus' idea of checking the values in pg_stat_get_progress_info() to
>>> determine whether to return NULL seems fine to me.

So you think that the latest patch is good enough?

>>> We will need to
>>> update the documentation of st_progress_param, because it currently
>>> says:
>>>
>>> * ...but the meaning of each element in the
>>> * st_progress_param array is command-specific.
>>> */
>>> ProgressCommandType st_progress_command;
>>> Oid st_progress_command_target;
>>> int64 st_progress_param[PGSTAT_NUM_PROGRESS_PARAM];
>>> } PgBackendStatus;
>>>
>>> If we are to define -1 in st_progress_param[] as NULL to the users,
>>> that must be mentioned here.
>>
>> Hmm, why -1? It seems like a value that we might want to use for other
>> purposes in other params. Maybe INT64_MIN is a better choice?
>
> Yes, maybe.

I don't think that we need to define the specific value like -1 as NULL globally.
Which value should be used for that purpose may vary by each command. Only for
pg_stat_progress_basebackup.backup_total, IMO using -1 as special value for
NULL is not so bad idea.

Regards,

--
Fujii Masao
NTT DATA CORPORATION
Advanced Platform Technology Group
Research and Development Headquarters