postgres_exporter/pkg/queries/builtin/query_overrides.go

package builtin

import (
	"github.com/blang/semver"
	. "github.com/wrouesnel/postgres_exporter/pkg/queries/metricmaps"
)

// Overriding queries for namespaces above.
// TODO: validate this is a closed set in tests, and there are no overlaps
var queryOverrides = map[string][]OverrideQuery{
	"pg_locks": {
		{
			semver.MustParseRange(">0.0.0"),
			`SELECT pg_database.datname,tmp.mode,COALESCE(count,0) as count
			FROM
				(
				  VALUES ('accesssharelock'),
				         ('rowsharelock'),
				         ('rowexclusivelock'),
				         ('shareupdateexclusivelock'),
				         ('sharelock'),
				         ('sharerowexclusivelock'),
				         ('exclusivelock'),
				         ('accessexclusivelock')
				) AS tmp(mode) CROSS JOIN pg_database
			LEFT JOIN
			  (SELECT database, lower(mode) AS mode,count(*) AS count
			  FROM pg_locks WHERE database IS NOT NULL
			  GROUP BY database, lower(mode)
			) AS tmp2
			ON tmp.mode=tmp2.mode and pg_database.oid = tmp2.database ORDER BY 1`,
		},
	},

	"pg_stat_replication": {
		{
			semver.MustParseRange(">=10.0.0"),
			`
			SELECT *,
				(case pg_is_in_recovery() when 't' then null else pg_current_wal_lsn() end) AS pg_current_wal_lsn,
				(case pg_is_in_recovery() when 't' then null else pg_wal_lsn_diff(pg_current_wal_lsn(), pg_lsn('0/0'))::float end) AS pg_current_wal_lsn_bytes,
				(case pg_is_in_recovery() when 't' then null else pg_wal_lsn_diff(pg_current_wal_lsn(), replay_lsn)::float end) AS pg_wal_lsn_diff
			FROM pg_stat_replication
			`,
		},
		{
			semver.MustParseRange(">=9.2.0 <10.0.0"),
			`
			SELECT *,
				(case pg_is_in_recovery() when 't' then null else pg_current_xlog_location() end) AS pg_current_xlog_location,
				(case pg_is_in_recovery() when 't' then null else pg_xlog_location_diff(pg_current_xlog_location(), replay_location)::float end) AS pg_xlog_location_diff
			FROM pg_stat_replication
			`,
		},
		{
			semver.MustParseRange("<9.2.0"),
			`
			SELECT *,
				(case pg_is_in_recovery() when 't' then null else pg_current_xlog_location() end) AS pg_current_xlog_location
			FROM pg_stat_replication
			`,
		},
	},

	"pg_stat_archiver": {
		{
			semver.MustParseRange(">=0.0.0"),
			`
			SELECT *,
				extract(epoch from now() - last_archived_time) AS last_archive_age
			FROM pg_stat_archiver
			`,
		},
	},

	"pg_stat_activity": {
		// This query only works
		{
			semver.MustParseRange(">=9.2.0"),
			`
			SELECT
				pg_database.datname,
				tmp.state,
				COALESCE(count,0) as count,
				COALESCE(max_tx_duration,0) as max_tx_duration
			FROM
				(
				  VALUES ('active'),
				  		 ('idle'),
				  		 ('idle in transaction'),
				  		 ('idle in transaction (aborted)'),
				  		 ('fastpath function call'),
				  		 ('disabled')
				) AS tmp(state) CROSS JOIN pg_database
			LEFT JOIN
			(
				SELECT
					datname,
					state,
					count(*) AS count,
					MAX(EXTRACT(EPOCH FROM now() - xact_start))::float AS max_tx_duration
				FROM pg_stat_activity GROUP BY datname,state) AS tmp2
				ON tmp.state = tmp2.state AND pg_database.datname = tmp2.datname
			`,
		},
		{
			semver.MustParseRange("<9.2.0"),
			`
			SELECT
				datname,
				'unknown' AS state,
				COALESCE(count(*),0) AS count,
				COALESCE(MAX(EXTRACT(EPOCH FROM now() - xact_start))::float,0) AS max_tx_duration
			FROM pg_stat_activity GROUP BY datname
			`,
		},
	},
}