PITR and instance without any activity

Hello,

I came across a weird problem about PITR with a recovery_target_time and 
a cluster without any activity. The issue is quite simple, we just try 
to do a PITR by specifying a recovery_target_time after the backup.

The main issue, is that there is no timestamp in the wal as there is no 
activity. Postgres fetches the record timestamp thanks to 
getRecordTimestamp:

/* 

  * Extract timestamp from WAL record. 

  * 

  * If the record contains a timestamp, returns true, and saves the 
timestamp
  * in *recordXtime. If the record type has no timestamp, returns false. 

  * Currently, only transaction commit/abort records and restore points 
contain
  * timestamps. 

  */ 


So, Postgres tries to replay all the wal until the end, and we got this 
message:
FATAL:  recovery ended before configured recovery target was reached

Before 13, promotion was done without any error:
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=dc788668bb269b10a108e87d14fefd1b9301b793

I wonder if we may add a timestamp for other wal records? Maybe when we 
switch xlog?

I may have spotted a bug, I tried to create restore point. I expected 
Postgres will get its timestamp as comment in getRecordTimestamp.
But Postgres did not find any timestamp and keep replaying the wal even 
after the restore point.

FYI, It seems I am not alone with this issue:
https://github.com/pgbackrest/pgbackrest/issues/1934
https://github.com/pgbackrest/pgbackrest/issues/1526#issuecomment-937759691

Thanks

-- 
Adrien NAYRAT