Re: proposal: get oldest LSN - function

On Sat, Feb 27, 2016 at 3:52 PM, Kartyshov Ivan
<i(dot)kartyshov(at)postgrespro(dot)ru> wrote:
> On 27.02.2016 03:07, Andres Freund wrote
>>
>> How does it help with any of that?
>
> Maybe i wasn't too accurate in terms, because I newbie, but:
> We can get information about xlog, using big amout of support function
> (pg_current_xlog_location(), pg_current_xlog_insert_location(),
> pg_xlogfile_name_offset(), pg_xlogfile_name(),
> pg_last_xlog_receive_location(), pg_last_xlog_replay_location(), ... etc)
> they helps to get get useful information about xlog files and its content.
> So, this patch extends this amount of functions.
> It is useful additional tool for DBA (we can get replicationSlotMinLSN, so
> why not in master), it can show us, if xlog replication or wal-sender is
> working properly or indicate if replication on startup can get up to date
> with master, or after long turnoff must be recovered from archive.

What pg_ls_dir('pg_xlog') couldn't do here if you need to know the
last WAL segment present on master?
--
Michael