From: pgsql-admin-owner@postgresql.
org [mailto:pgsql-admin-owner@postgresql.org ] On Behalf Of rammohan ganapavarapu
Sent: Tuesday, November 07, 2017 9:52 PM
To: pgsql-admin@xxxxxxxxxxxxxx
Subject: How to measure replication lag in logical replication setup.
HI,
How to measure replication lag time in case of logical replication?
this query is returning empty
SELECT now() - pg_last_xact_replay_timestamp(
) AS time_lag; time_lag
----------
(1 row)
this is my slot details
SELECT * FROM pg_replication_slots;
slot_name | plugin | slot_type | datoid | database | active | xmin | catalog_xmin | restart_lsn
-----------+--------+---------
--+--------+----------+------- -+------+--------------+------ ------- slot_1 | | physical | | | t | 1983 | | 0/50805C8
In my case slot_type is physical, does it look ok or for logical replication the slot_type should be logical?
Thanks,
Ram
I compare confirmed_flush_lsn in PG_REPLICATION_SLOTS on the Publisher with pg_current_wal_lsn():
SELECT confirmed_flush_lsn, pg_current_wal_lsn(), (pg_current_wal_lsn() - confirmed_flush_lsn) AS lsn_distance
FROM pg_catalog.pg_replication_
slots WHERE slot_name = 'subscriber_1';
slot_type for logical replication is logical.
Slot was created “automatically”, when I created “subscriber_1” subscription.
Regards,
Igor Neyman
Thank you Igor.
Ram
On Wed, Nov 8, 2017 at 7:39 AM, Igor Neyman <ineyman@xxxxxxxxxxxxxx> wrote:
