Re: pg_control_recovery() return value when not in recovery

On 09/17/2017 11:29 PM, Andres Freund wrote:
> On 2017-09-18 07:24:43 +0100, Simon Riggs wrote:
>> On 18 September 2017 at 05:50, Andres Freund <andres(at)anarazel(dot)de> wrote:
>> > Hi,
>> >
>> > Just noticed that we're returning the underlying values for
>> > pg_control_recovery() without any checks:
>> > postgres[14388][1]=# SELECT * FROM pg_control_recovery();
>> > ┌──────────────────────┬───────────────────────────┬──────────────────┬────────────────┬───────────────────────────────┐
>> > │ min_recovery_end_lsn │ min_recovery_end_timeline │ backup_start_lsn │ backup_end_lsn │ end_of_backup_record_required │
>> > ├──────────────────────┼───────────────────────────┼──────────────────┼────────────────┼───────────────────────────────┤
>> > │ 0/0 │ 0 │ 0/0 │ 0/0 │ f │
>> > └──────────────────────┴───────────────────────────┴──────────────────┴────────────────┴───────────────────────────────┘
>> > (1 row)
>>
>> Yes, that would have made sense for these to be NULL
>
> Yea, that's what I think was well. Joe, IIRC that's your code, do you
> agree as well?

Sorry for the slow response, but thinking back on this now, the idea of
these functions, in my mind at least, was to provide as close to the
same output as possible to what pg_controldata outputs. So:

# pg_controldata
...
Minimum recovery ending location: 0/0
Min recovery ending loc's timeline: 0
Backup start location: 0/0
Backup end location: 0/0
End-of-backup record required: no
...

So if we make a change here, do we also change pg_controldata?

Joe

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