Re: pg_basebackup and pg_stat_tmp directory

On Fri, Jan 31, 2014 at 10:18 PM, Mitsumasa KONDO
<kondo(dot)mitsumasa(at)gmail(dot)com> wrote:
> 2014-01-31 Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
>>
>> On Tue, Jan 28, 2014 at 5:51 PM, Magnus Hagander <magnus(at)hagander(dot)net>
>> wrote:
>> > On Tue, Jan 28, 2014 at 6:11 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
>> > wrote:
>> >>
>> >> On Tue, Jan 28, 2014 at 9:26 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
>> >> wrote:
>> >> > Hi,
>> >> >
>> >> > The files in pg_stat_tmp directory don't need to be backed up because
>> >> > they are
>> >> > basically reset at the archive recovery. So I think it's worth
>> >> > changing pg_basebackup
>> >> > so that it skips any files in pg_stat_tmp directory. Thought?
>> >>
>> >> I think this is good idea, but can't it also avoid
>> >> PGSTAT_STAT_PERMANENT_TMPFILE along with temp files in
>> >> pg_stat_tmp
>> >>
>> >
>> > All stats files should be excluded. IIRC the
>> > PGSTAT_STAT_PERMANENT_TMPFILE
>> > refers to just the global one. You want to exclude based on
>> > PGSTAT_STAT_PERMANENT_DIRECTORY (and of course based on the guc
>> > stats_temp_directory if it's in PGDATA.
>>
>> Attached patch changes basebackup.c so that it skips all files in both
>> pg_stat_tmp
>> and stats_temp_directory. Even when a user sets stats_temp_directory
>> to the directory
>> other than pg_stat_tmp, we need to skip the files in pg_stat_tmp. Because,
>> per recent change of pg_stat_statements, the external query file is
>> always created there.
>
> +1.
>
> And, I'd like to also skip pg_log directory because security reason.

Yeah, I was thinking that, too. I'm not sure whether including log files
in backup really increases the security risk, though. There are already
very important data, i.e., database, in backups. Anyway, since
the amount of log files can be very large and they are not essential
for recovery, it's worth considering whether to exclude them. OTOH,
I'm sure that some users prefer current behavior for some reasons.
So I think that it's better to expose the pg_basebackup option
specifying whether log files are included in backups or not.

Regards,

--
Fujii Masao