Re: Stronger safeguard for archive recovery not to miss data

On 2021/01/20 1:05, Laurenz Albe wrote:
> On Mon, 2021-01-18 at 07:34 +0000, osumi(dot)takamichi(at)fujitsu(dot)com wrote:
>> I noticed that this message should cover both archive recovery modes,
>> which means in recovery mode and standby mode. Then, I combined your
>> suggestion above with this point of view. Have a look at the updated patch.
>> I also enriched the new tap tests to show this perspective.
>
> Looks good, thanks.
>
> I'll mark this patch as "ready for committer".

+ errhint("Run recovery again from a new base backup taken after setting wal_level higher than minimal")));

Isn't it impossible to do this in normal archive recovery case? In that case,
since the server crashed and the database got corrupted, probably
we cannot take a new base backup.

Originally even when users accidentally set wal_level to minimal, they could
start the server from the backup by disabling hot_standby and salvage the data.
But with the patch, we lost the way to do that. Right? I was wondering that
WARNING was used intentionally there for that case.

if (ControlFile->wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
(errmsg("hot standby is not possible because wal_level was not set to \"replica\" or higher on the primary server"),
errhint("Either set wal_level to \"replica\" on the primary, or turn off hot_standby here.")));

With the patch, we never reach the above code?

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION