Обсуждение: xmin horizon?

All;

The documentation for pg_stat_activity lists this column:

backend_xmin     xid     The current backend's xmin horizon.

Can someone point me to a better understanding on "xmin horizon"?

Thanks in advance

On Thu, Jul 30, 2015 at 4:13 AM, CS DBA <cs_dba@consistentstate.com> wrote:
> The documentation for pg_stat_activity lists this column:
>
> backend_xmin     xid     The current backend's xmin horizon.
>
> Can someone point me to a better understanding on "xmin horizon"?

This defines the oldest transaction ID that a given backend is currently seeing.
--
Michael

On 29/07/15 21:13, CS DBA wrote:
> The documentation for pg_stat_activity lists this column:
>
> backend_xmin     xid     The current backend's xmin horizon.
>
> Can someone point me to a better understanding on "xmin horizon"?

https://momjian.us/main/writings/pgsql/mvcc.pdf

you can find this talk also on youtube. It's worth watching.

Torsten