[+] add sent_lag and confirmed_flush_lsn_lag fields to replicatio…

…n metrics (#700)

* Additional metrics based on stat_statements stats
* updating the files in the `metric` folder
---------
Co-authored-by: Mikhail.Balayan <mikhail.balayan@acronis.com>

pgwatch2/metrics/replication/10/metric.sql

@@ -2,6 +2,7 @@ select /* pgwatch2_generated */
   (extract(epoch from now()) * 1e9)::int8 as epoch_ns,
   application_name as tag_application_name,
   concat(coalesce(client_addr::text, client_hostname), '_', client_port::text) as tag_client_info,
+  coalesce(pg_wal_lsn_diff(case when pg_is_in_recovery() then pg_last_wal_receive_lsn() else pg_current_wal_lsn() end, sent_lsn)::int8, 0) as sent_lag_b,
   coalesce(pg_wal_lsn_diff(case when pg_is_in_recovery() then pg_last_wal_receive_lsn() else pg_current_wal_lsn() end, write_lsn)::int8, 0) as write_lag_b,
   coalesce(pg_wal_lsn_diff(case when pg_is_in_recovery() then pg_last_wal_receive_lsn() else pg_current_wal_lsn() end, flush_lsn)::int8, 0) as flush_lag_b,
   coalesce(pg_wal_lsn_diff(case when pg_is_in_recovery() then pg_last_wal_receive_lsn() else pg_current_wal_lsn() end, replay_lsn)::int8, 0) as replay_lag_b,

pgwatch2/metrics/replication_slots/10/metric_master.sql

@@ -5,6 +5,7 @@ select /* pgwatch2_generated */
   active,
   case when active then 0 else 1 end as non_active_int,
   pg_wal_lsn_diff(pg_current_wal_lsn(), restart_lsn)::int8 as restart_lsn_lag_b,
+  pg_wal_lsn_diff(pg_current_wal_lsn(), confirmed_flush_lsn)::int8 as confirmed_flush_lsn_lag_b,
   greatest(age(xmin), age(catalog_xmin))::int8 as xmin_age_tx
 from
   pg_replication_slots;

pgwatch2/sql/config_store/metric_definitions.sql

@@ -1834,6 +1834,7 @@ SELECT
   (extract(epoch from now()) * 1e9)::int8 as epoch_ns,
   application_name as tag_application_name,
   concat(coalesce(client_addr::text, client_hostname), '_', client_port::text) as tag_client_info,
+  coalesce(pg_wal_lsn_diff(case when pg_is_in_recovery() then pg_last_wal_receive_lsn() else pg_current_wal_lsn() end, sent_lsn)::int8, 0) as sent_lag_b,
   coalesce(pg_wal_lsn_diff(case when pg_is_in_recovery() then pg_last_wal_receive_lsn() else pg_current_wal_lsn() end, write_lsn)::int8, 0) as write_lag_b,
   coalesce(pg_wal_lsn_diff(case when pg_is_in_recovery() then pg_last_wal_receive_lsn() else pg_current_wal_lsn() end, flush_lsn)::int8, 0) as flush_lag_b,
   coalesce(pg_wal_lsn_diff(case when pg_is_in_recovery() then pg_last_wal_receive_lsn() else pg_current_wal_lsn() end, replay_lsn)::int8, 0) as replay_lag_b,
@@ -6929,6 +6930,7 @@ select
   active,
   case when active then 0 else 1 end as non_active_int,
   pg_wal_lsn_diff(pg_current_wal_lsn(), restart_lsn)::int8 as restart_lsn_lag_b,
+  pg_wal_lsn_diff(pg_current_wal_lsn(), confirmed_flush_lsn)::int8 as confirmed_flush_lsn_lag_b,
   greatest(age(xmin), age(catalog_xmin))::int8 as xmin_age_tx
 from
   pg_replication_slots;