Record table only size bytes as well in addition to the total size bytes

Signed-off-by: Felix Yuan <felix.yuan@reddit.com>

collector/pg_stat_user_tables.go

@@ -156,6 +156,12 @@ var (
 		[]string{"datname", "schemaname", "relname"},
 		prometheus.Labels{},
 	)
+	statUserTablesOnlySize = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, userTableSubsystem, "only_size_bytes"),
+		"Total disk space used by only this table, in bytes",
+		[]string{"datname", "schemaname", "relname"},
+		prometheus.Labels{},
+	)
 
 	statUserTablesQuery = `SELECT
 		current_database() datname,
@@ -180,7 +186,8 @@ var (
 		autovacuum_count,
 		analyze_count,
 		autoanalyze_count,
-		pg_total_relation_size(relid) as total_size
+		pg_total_relation_size(relid) as total_size,
+		pg_table_size(relid) as table_only_size
 	FROM
 		pg_stat_user_tables`
 )
@@ -198,10 +205,10 @@ func (c *PGStatUserTablesCollector) Update(ctx context.Context, instance *instan
 	for rows.Next() {
 		var datname, schemaname, relname sql.NullString
 		var seqScan, seqTupRead, idxScan, idxTupFetch, nTupIns, nTupUpd, nTupDel, nTupHotUpd, nLiveTup, nDeadTup,
-			nModSinceAnalyze, vacuumCount, autovacuumCount, analyzeCount, autoanalyzeCount, totalSize sql.NullInt64
+			nModSinceAnalyze, vacuumCount, autovacuumCount, analyzeCount, autoanalyzeCount, totalSize, tableOnlySize sql.NullInt64
 		var lastVacuum, lastAutovacuum, lastAnalyze, lastAutoanalyze sql.NullTime
 
-		if err := rows.Scan(&datname, &schemaname, &relname, &seqScan, &seqTupRead, &idxScan, &idxTupFetch, &nTupIns, &nTupUpd, &nTupDel, &nTupHotUpd, &nLiveTup, &nDeadTup, &nModSinceAnalyze, &lastVacuum, &lastAutovacuum, &lastAnalyze, &lastAutoanalyze, &vacuumCount, &autovacuumCount, &analyzeCount, &autoanalyzeCount, &totalSize); err != nil {
+		if err := rows.Scan(&datname, &schemaname, &relname, &seqScan, &seqTupRead, &idxScan, &idxTupFetch, &nTupIns, &nTupUpd, &nTupDel, &nTupHotUpd, &nLiveTup, &nDeadTup, &nModSinceAnalyze, &lastVacuum, &lastAutovacuum, &lastAnalyze, &lastAutoanalyze, &vacuumCount, &autovacuumCount, &analyzeCount, &autoanalyzeCount, &totalSize, &tableOnlySize); err != nil {
 			return err
 		}
 
@@ -437,6 +444,17 @@ func (c *PGStatUserTablesCollector) Update(ctx context.Context, instance *instan
 			totalSizeMetric,
 			datnameLabel, schemanameLabel, relnameLabel,
 		)
+
+		tableOnlySizeMetric := 0.0
+		if tableOnlySize.Valid {
+			tableOnlySizeMetric = float64(tableOnlySize.Int64)
+		}
+		ch <- prometheus.MustNewConstMetric(
+			statUserTablesOnlySize,
+			prometheus.GaugeValue,
+			tableOnlySizeMetric,
+			datnameLabel, schemanameLabel, relnameLabel,
+		)
 	}
 
 	if err := rows.Err(); err != nil {

collector/pg_stat_user_tables_test.go

@@ -72,7 +72,8 @@ func TestPGStatUserTablesCollector(t *testing.T) {
 		"autovacuum_count",
 		"analyze_count",
 		"autoanalyze_count",
-		"total_size"}
+		"total_size",
+		"table_only_size"}
 	rows := sqlmock.NewRows(columns).
 		AddRow("postgres",
 			"public",
@@ -96,7 +97,8 @@ func TestPGStatUserTablesCollector(t *testing.T) {
 			12,
 			13,
 			14,
-			15)
+			15,
+			16)
 	mock.ExpectQuery(sanitizeQuery(statUserTablesQuery)).WillReturnRows(rows)
 	ch := make(chan prometheus.Metric)
 	go func() {
@@ -128,6 +130,8 @@ func TestPGStatUserTablesCollector(t *testing.T) {
 		{labels: labelMap{"datname": "postgres", "schemaname": "public", "relname": "a_table"}, metricType: dto.MetricType_COUNTER, value: 12},
 		{labels: labelMap{"datname": "postgres", "schemaname": "public", "relname": "a_table"}, metricType: dto.MetricType_COUNTER, value: 13},
 		{labels: labelMap{"datname": "postgres", "schemaname": "public", "relname": "a_table"}, metricType: dto.MetricType_COUNTER, value: 14},
+		{labels: labelMap{"datname": "postgres", "schemaname": "public", "relname": "a_table"}, metricType: dto.MetricType_GAUGE, value: 15},
+		{labels: labelMap{"datname": "postgres", "schemaname": "public", "relname": "a_table"}, metricType: dto.MetricType_GAUGE, value: 16},
 	}
 
 	convey.Convey("Metrics comparison", t, func() {
@@ -173,7 +177,8 @@ func TestPGStatUserTablesCollectorNullValues(t *testing.T) {
 		"autovacuum_count",
 		"analyze_count",
 		"autoanalyze_count",
-		"total_size"}
+		"total_size",
+		"table_only_size"}
 	rows := sqlmock.NewRows(columns).
 		AddRow("postgres",
 			nil,
@@ -197,6 +202,7 @@ func TestPGStatUserTablesCollectorNullValues(t *testing.T) {
 			nil,
 			nil,
 			nil,
+			nil,
 			nil)
 	mock.ExpectQuery(sanitizeQuery(statUserTablesQuery)).WillReturnRows(rows)
 	ch := make(chan prometheus.Metric)
@@ -229,6 +235,8 @@ func TestPGStatUserTablesCollectorNullValues(t *testing.T) {
 		{labels: labelMap{"datname": "postgres", "schemaname": "unknown", "relname": "unknown"}, metricType: dto.MetricType_COUNTER, value: 0},
 		{labels: labelMap{"datname": "postgres", "schemaname": "unknown", "relname": "unknown"}, metricType: dto.MetricType_COUNTER, value: 0},
 		{labels: labelMap{"datname": "postgres", "schemaname": "unknown", "relname": "unknown"}, metricType: dto.MetricType_COUNTER, value: 0},
+		{labels: labelMap{"datname": "postgres", "schemaname": "unknown", "relname": "unknown"}, metricType: dto.MetricType_GAUGE, value: 0},
+		{labels: labelMap{"datname": "postgres", "schemaname": "unknown", "relname": "unknown"}, metricType: dto.MetricType_GAUGE, value: 0},
 	}
 
 	convey.Convey("Metrics comparison", t, func() {