Add Table size metric

gauges/table_sizes.go

@@ -0,0 +1,65 @@
+package gauges
+
+import (
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const tableSizesQuery = `
+	SELECT
+		ut.relname AS table_name,
+		pg_indexes_size(c.oid) AS index_size,
+		COALESCE(pg_total_relation_size(c.reltoastrelid), 0) AS toast_size,
+		pg_total_relation_size(c.oid)
+			- pg_indexes_size(c.oid)
+			- COALESCE(pg_total_relation_size(c.reltoastrelid), 0) AS table_size
+	FROM
+		pg_stat_user_tables ut
+		JOIN pg_class c on ut.relname = c.relname
+`
+
+type tableSizes struct {
+	Name      string  `db:"table_name"`
+	IndexSize float64 `db:"index_size"`
+	ToastSize float64 `db:"toast_size"`
+	TableSize float64 `db:"table_size"`
+}
+
+// TableSizes returns the total disk space in bytes used by the a table,
+// including all indexes and TOAST data
+func (g *Gauges) TableSizes() *prometheus.GaugeVec {
+	var gauge = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name:        "postgresql_table_size_bytes",
+			Help:        "Total disk space in bytes used by the a table, including all indexes and TOAST data",
+			ConstLabels: g.labels,
+		},
+		[]string{"table", "type"},
+	)
+
+	go func() {
+		for {
+			var tables []tableSizes
+			if err := g.query(tableSizesQuery, &tables, emptyParams); err == nil {
+				for _, table := range tables {
+					gauge.With(prometheus.Labels{
+						"table": table.Name,
+						"type":  "index",
+					}).Set(table.IndexSize)
+					gauge.With(prometheus.Labels{
+						"table": table.Name,
+						"type":  "toast",
+					}).Set(table.ToastSize)
+					gauge.With(prometheus.Labels{
+						"table": table.Name,
+						"type":  "table",
+					}).Set(table.TableSize)
+				}
+			}
+			time.Sleep(g.interval)
+		}
+	}()
+
+	return gauge
+}

gauges/table_sizes_test.go

@@ -0,0 +1,22 @@
+package gauges
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTableSizes(t *testing.T) {
+	var assert = assert.New(t)
+	db, gauges, close := prepare(t)
+	defer close()
+	dropTestTable := createTestTable(t, db)
+	defer dropTestTable()
+
+	var metrics = evaluate(t, gauges.TableSizes())
+	assert.Len(metrics, 3)
+	for _, metric := range metrics {
+		assertEqual(t, 0, metric)
+	}
+	assertNoErrs(t, gauges)
+}

main.go

@@ -106,6 +106,7 @@ func watch(db *sql.DB, reg prometheus.Registerer, name string) {
 	reg.MustRegister(gauges.UnusedIndexes())
 	reg.MustRegister(gauges.Up())
 	reg.MustRegister(gauges.TableScans())
+	reg.MustRegister(gauges.TableSizes())
 	reg.MustRegister(gauges.DatabaseReadingUsage())
 	reg.MustRegister(gauges.DatabaseWritingUsage())
 	reg.MustRegister(gauges.HOTUpdates())