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Fix pg_stat_replication compatibility on older pg versions #103

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Feb 23, 2025
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Fix pg_stat_replication compatibility on older pg versions #103

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99 changes: 98 additions & 1 deletion powa--5.0.1--5.0.2.sql
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Original file line number Diff line number Diff line change
Expand Up @@ -390,4 +390,101 @@ BEGIN
$PROC$ LANGUAGE plpgsql
SET search_path = pg_catalog; /* end of powa_user_functions_aggregate */


CREATE OR REPLACE FUNCTION @[email protected]_stat_replication_src(IN _srvid integer,
OUT ts timestamp with time zone,
OUT current_lsn pg_lsn,
OUT pid integer,
OUT usename text,
OUT application_name text,
OUT client_addr inet,
OUT backend_start timestamp with time zone,
OUT backend_xmin xid,
OUT state text,
OUT sent_lsn pg_lsn,
OUT write_lsn pg_lsn,
OUT flush_lsn pg_lsn,
OUT replay_lsn pg_lsn,
OUT write_lag interval,
OUT flush_lag interval,
OUT replay_lag interval,
OUT sync_priority integer,
OUT sync_state text,
OUT reply_time timestamp with time zone
) RETURNS SETOF record STABLE AS $PROC$
DECLARE
v_current_lsn pg_lsn;
v_pg_version_num int;
BEGIN
IF (_srvid = 0) THEN
v_pg_version_num := current_setting('server_version_num')::int;

IF v_pg_version_num < 100000 THEN
IF pg_is_in_recovery() THEN
v_current_lsn := pg_last_xlog_receive_location();
ELSE
v_current_lsn := pg_current_xlog_location();
END IF;
ELSE
IF pg_is_in_recovery() THEN
v_current_lsn := pg_last_wal_receive_lsn();
ELSE
v_current_lsn := pg_current_wal_lsn();
END IF;
END IF;

-- We use a LEFT JOIN on the pg_stat_replication view to make sure that
-- we always return at least one (all-NULL) row, so client apps can
-- detect when all the replication connections are down.
--
-- We handle older versions compatibility even if we don't actually
-- enable them for pg 12 and below, are there are no aggregate
-- functions for pg_lsn datatype before pg13. This way if the
-- repository server is on pg13+ and a remote is on pg12-, we can still
-- support that datasource.

-- pg12+, reply_time is added
IF v_pg_version_num >= 120000 THEN
RETURN QUERY SELECT now,
v_current_lsn,
s.pid, s.usename::text AS usename, s.application_name, s.client_addr,
s.backend_start, s.backend_xmin, s.state, s.sent_lsn, s.write_lsn,
s.flush_lsn, s.replay_lsn, s.write_lag, s.flush_lag, s.replay_lag,
s.sync_priority, s.sync_state, s.reply_time
FROM (SELECT now() AS now) n
LEFT JOIN pg_catalog.pg_stat_replication AS s ON true;
-- pg10+, *_location fields renamed to *_lsn, and *_lag fields added
ELSIF v_pg_version_num >= 100000 THEN
RETURN QUERY SELECT now,
v_current_lsn,
s.pid, s.usename::text AS usename, s.application_name, s.client_addr,
s.backend_start, s.backend_xmin, s.state, s.sent_lsn, s.write_lsn,
s.flush_lsn, s.replay_lsn, s.write_lag, s.flush_lag, s.replay_lag,
s.sync_priority, s.sync_state, NULL::timestamptz AS reply_time
FROM (SELECT now() AS now) n
LEFT JOIN pg_catalog.pg_stat_replication AS s ON true;
-- pg9.4+ definition
ELSE
RETURN QUERY SELECT now,
v_current_lsn,
s.pid, s.usename::text AS usename, s.application_name, s.client_addr,
s.backend_start, s.backend_xmin, s.state,
s.sent_location AS sent_lsn, s.write_location AS write_lsn,
s.flush_location AS flush_lsn, s.replay_location AS replay_lsn,
NULL::interval AS write_lag, NULL::interval AS flush_lag,
NULL::interval AS replay_lag,
s.sync_priority, s.sync_state, NULL::timestamptz AS reply_time
FROM (SELECT now() AS now) n
LEFT JOIN pg_catalog.pg_stat_replication AS s ON true;
END IF;
ELSE
RETURN QUERY SELECT s.ts,
s.current_lsn,
s.pid, s.usename, s.application_name, s.client_addr,
s.backend_start, s.backend_xmin, s.state, s.sent_lsn, s.write_lsn,
s.flush_lsn, s.replay_lsn, s.write_lag, s.flush_lag, s.replay_lag,
s.sync_priority, s.sync_state, s.reply_time
FROM @[email protected]_stat_replication_src_tmp AS s
WHERE s.srvid = _srvid;
END IF;
END;
$PROC$ LANGUAGE plpgsql; /* end of powa_stat_replication_src */
55 changes: 46 additions & 9 deletions powa--5.0.2.sql
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Original file line number Diff line number Diff line change
Expand Up @@ -1781,6 +1781,7 @@ pid, usename, application_name, client_addr, backend_start, backend_xmin,
state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag,
replay_lag, sync_priority, sync_state, reply_time
}$$,
-- pg_lsn aggregates only exists on pg13+
_min_version => 130000
);

Expand Down Expand Up @@ -4789,9 +4790,12 @@ CREATE OR REPLACE FUNCTION @[email protected]_stat_replication_src(IN _srvid integ
) RETURNS SETOF record STABLE AS $PROC$
DECLARE
v_current_lsn pg_lsn;
v_pg_version_num int;
BEGIN
IF (_srvid = 0) THEN
IF current_setting('server_version_num')::int < 100000 THEN
v_pg_version_num := current_setting('server_version_num')::int;

IF v_pg_version_num < 100000 THEN
IF pg_is_in_recovery() THEN
v_current_lsn := pg_last_xlog_receive_location();
ELSE
Expand All @@ -4808,14 +4812,47 @@ BEGIN
-- We use a LEFT JOIN on the pg_stat_replication view to make sure that
-- we always return at least one (all-NULL) row, so client apps can
-- detect when all the replication connections are down.
RETURN QUERY SELECT now,
v_current_lsn,
s.pid, s.usename::text AS usename, s.application_name, s.client_addr,
s.backend_start, s.backend_xmin, s.state, s.sent_lsn, s.write_lsn,
s.flush_lsn, s.replay_lsn, s.write_lag, s.flush_lag, s.replay_lag,
s.sync_priority, s.sync_state, s.reply_time
FROM (SELECT now() AS now) n
LEFT JOIN pg_catalog.pg_stat_replication AS s ON true;
--
-- We handle older versions compatibility even if we don't actually
-- enable them for pg 12 and below, are there are no aggregate
-- functions for pg_lsn datatype before pg13. This way if the
-- repository server is on pg13+ and a remote is on pg12-, we can still
-- support that datasource.

-- pg12+, reply_time is added
IF v_pg_version_num >= 120000 THEN
RETURN QUERY SELECT now,
v_current_lsn,
s.pid, s.usename::text AS usename, s.application_name, s.client_addr,
s.backend_start, s.backend_xmin, s.state, s.sent_lsn, s.write_lsn,
s.flush_lsn, s.replay_lsn, s.write_lag, s.flush_lag, s.replay_lag,
s.sync_priority, s.sync_state, s.reply_time
FROM (SELECT now() AS now) n
LEFT JOIN pg_catalog.pg_stat_replication AS s ON true;
-- pg10+, *_location fields renamed to *_lsn, and *_lag fields added
ELSIF v_pg_version_num >= 100000 THEN
RETURN QUERY SELECT now,
v_current_lsn,
s.pid, s.usename::text AS usename, s.application_name, s.client_addr,
s.backend_start, s.backend_xmin, s.state, s.sent_lsn, s.write_lsn,
s.flush_lsn, s.replay_lsn, s.write_lag, s.flush_lag, s.replay_lag,
s.sync_priority, s.sync_state, NULL::timestamptz AS reply_time
FROM (SELECT now() AS now) n
LEFT JOIN pg_catalog.pg_stat_replication AS s ON true;
-- pg9.4+ definition
ELSE
RETURN QUERY SELECT now,
v_current_lsn,
s.pid, s.usename::text AS usename, s.application_name, s.client_addr,
s.backend_start, s.backend_xmin, s.state,
s.sent_location AS sent_lsn, s.write_location AS write_lsn,
s.flush_location AS flush_lsn, s.replay_location AS replay_lsn,
NULL::interval AS write_lag, NULL::interval AS flush_lag,
NULL::interval AS replay_lag,
s.sync_priority, s.sync_state, NULL::timestamptz AS reply_time
FROM (SELECT now() AS now) n
LEFT JOIN pg_catalog.pg_stat_replication AS s ON true;
END IF;
ELSE
RETURN QUERY SELECT s.ts,
s.current_lsn,
Expand Down