RE: invalid data in file backup_label problem on windows

Hi, 

David Steele <david@pgmasters.net> wrote:

> I'm not sure how I feel about this patch (not really a Windows person)  
> but I do think that you shouldn't modify the backup_label when writing  
> it, i.e. you should be writing backup_label in binary mode to avoid this  
> issue.

IMO, I don't modify backup_lable, I just execute select * FROM pg_stop_backup(),
copy the result from terminal to a file and save the file, but most of editor on 
Windows will using CRLF as default to edit file, such as notepad, notepad++.

BTW, in [1]
> The pg_stop_backup will return one row with three values. The second 
> of these fields should be written to a file named backup_label in the root 
> directory of the backup. The third field should be written to a file named 
> tablespace_map unless the field is empty. These files are vital to the backup 
> working, and must be written without modification.

Do not use CRLF to edit a backup_label on windows is not mentioned. 

> No objections from me if it gets committed but I'm not sure it should be  
> classified as a "bug fix" since the backup_label was modified from what  
> postgres provided, unless I am misunderstanding.

I think the backup_label is not a postgres provided file(using Non-Exclusive Low Level API), 
this file must be created by user. 
If users use Exclusive Low Level API or pg_basebakup, this file will be auto created, and
users will not edit this file.

Therefore, I think this is a bug instead of a misuse

[1] https://www.postgresql.org/docs/13/continuous-archiving.html#BACKUP-LOWLEVEL-BASE-BACKUP

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Best Regards
Shenhao Wang