feat: add support for pg_stat_user_indexes

README.md

@@ -147,6 +147,9 @@ This will build the docker image as `prometheuscommunity/postgres_exporter:${bra
 * `[no-]collector.stat_statements`
   Enable the `stat_statements` collector (default: disabled).
 
+* `[no-]collector.stat_user_indexes`
+  Enable the `stat_user_indexes` collector (default: disabled).
+
 * `[no-]collector.stat_user_tables`
   Enable the `stat_user_tables` collector (default: enabled).
 

collector/pg_stat_user_indexes.go

@@ -0,0 +1,192 @@
+// Copyright 2023 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package collector
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strings"
+
+	"github.com/blang/semver/v4"
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func init() {
+	registerCollector(statUserIndexesSubsystem, defaultDisabled, NewPGStatUserIndexesCollector)
+}
+
+type PGStatUserIndexesCollector struct {
+	log log.Logger
+}
+
+const statUserIndexesSubsystem = "stat_user_indexes"
+
+func NewPGStatUserIndexesCollector(config collectorConfig) (Collector, error) {
+	return &PGStatUserIndexesCollector{log: config.logger}, nil
+}
+
+var (
+	statUserIndexesIdxScan = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, statUserIndexesSubsystem, "idx_scan_total"),
+		"Number of scans for this index",
+		[]string{"datname", "schemaname", "relname", "indexrelname"},
+		prometheus.Labels{},
+	)
+
+	statUserIndexesLastIdxScan = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, statUserIndexesSubsystem, "last_idx_scan_time"),
+		"Last timestamp of scan for this index",
+		[]string{"datname", "schemaname", "relname", "indexrelname"},
+		prometheus.Labels{},
+	)
+
+	statUserIndexesIdxTupRead = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, statUserIndexesSubsystem, "idx_tup_read"),
+		"Number of tuples read for this index",
+		[]string{"datname", "schemaname", "relname", "indexrelname"},
+		prometheus.Labels{},
+	)
+
+	statUserIndexesIdxTupFetch = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, statUserIndexesSubsystem, "idx_tup_fetch"),
+		"Number of tuples fetch for this index",
+		[]string{"datname", "schemaname", "relname", "indexrelname"},
+		prometheus.Labels{},
+	)
+)
+
+func statUserIndexesQuery(columns []string) string {
+	return fmt.Sprintf("SELECT %s FROM pg_stat_user_indexes;", strings.Join(columns, ","))
+}
+
+func (c *PGStatUserIndexesCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
+	db := instance.getDB()
+
+	columns := []string{
+		"current_database() datname",
+		"schemaname",
+		"relname",
+		"indexrelname",
+		"idx_scan",
+		"idx_tup_read",
+		"idx_tup_fetch",
+	}
+
+	lastIdxScanAvail := instance.version.GTE(semver.MustParse("16.0.0"))
+	if lastIdxScanAvail {
+		columns = append(columns, "date_part('epoch', last_idx_scan) as last_idx_scan")
+	}
+
+	rows, err := db.QueryContext(ctx,
+		statUserIndexesQuery(columns),
+	)
+
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var datname, schemaname, relname, indexrelname sql.NullString
+		var idxScan, lastIdxScan, idxTupRead, idxTupFetch sql.NullFloat64
+
+		r := []any{
+			&datname,
+			&schemaname,
+			&relname,
+			&indexrelname,
+			&idxScan,
+			&idxTupRead,
+			&idxTupFetch,
+		}
+
+		if lastIdxScanAvail {
+			r = append(r, &lastIdxScan)
+		}
+
+		if err := rows.Scan(r...); err != nil {
+			return err
+		}
+		datnameLabel := "unknown"
+		if datname.Valid {
+			datnameLabel = datname.String
+		}
+		schemanameLabel := "unknown"
+		if schemaname.Valid {
+			schemanameLabel = schemaname.String
+		}
+		relnameLabel := "unknown"
+		if relname.Valid {
+			relnameLabel = relname.String
+		}
+		indexrelnameLabel := "unknown"
+		if indexrelname.Valid {
+			indexrelnameLabel = indexrelname.String
+		}
+
+		if lastIdxScanAvail && !lastIdxScan.Valid {
+			level.Debug(c.log).Log("msg", "Skipping collecting metric because it has no active_time")
+			continue
+		}
+
+		labels := []string{datnameLabel, schemanameLabel, relnameLabel, indexrelnameLabel}
+
+		idxScanMetric := 0.0
+		if idxScan.Valid {
+			idxScanMetric = idxScan.Float64
+		}
+		ch <- prometheus.MustNewConstMetric(
+			statUserIndexesIdxScan,
+			prometheus.CounterValue,
+			idxScanMetric,
+			labels...,
+		)
+
+		idxTupReadMetric := 0.0
+		if idxTupRead.Valid {
+			idxTupReadMetric = idxTupRead.Float64
+		}
+		ch <- prometheus.MustNewConstMetric(
+			statUserIndexesIdxTupRead,
+			prometheus.CounterValue,
+			idxTupReadMetric,
+			labels...,
+		)
+
+		idxTupFetchMetric := 0.0
+		if idxTupFetch.Valid {
+			idxTupFetchMetric = idxTupFetch.Float64
+		}
+		ch <- prometheus.MustNewConstMetric(
+			statUserIndexesIdxTupFetch,
+			prometheus.CounterValue,
+			idxTupFetchMetric,
+			labels...,
+		)
+
+		if lastIdxScanAvail {
+			ch <- prometheus.MustNewConstMetric(
+				statUserIndexesLastIdxScan,
+				prometheus.CounterValue,
+				lastIdxScan.Float64,
+				labels...,
+			)
+		}
+	}
+	if err := rows.Err(); err != nil {
+		return err
+	}
+	return nil
+}

collector/pg_stat_user_indexes_test.go

@@ -0,0 +1,81 @@
+// Copyright 2023 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package collector
+
+import (
+	"context"
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+	"github.com/smartystreets/goconvey/convey"
+)
+
+func TestPgStatUserIndexesCollector(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	if err != nil {
+		t.Fatalf("Error opening a stub db connection: %s", err)
+	}
+	defer db.Close()
+	inst := &instance{db: db}
+
+	columns := []string{
+		"datname",
+		"schemaname",
+		"relname",
+		"indexrelname",
+		"idx_scan",
+		"idx_tup_read",
+		"idx_tup_fetch",
+	}
+	rows := sqlmock.NewRows(columns).
+		AddRow("postgres", "public", "pgtest_accounts", "pgtest_accounts_pkey", "8", "9", "5")
+
+	cols := []string{
+		"current_database() datname",
+		"schemaname",
+		"relname",
+		"indexrelname",
+		"idx_scan",
+		"idx_tup_read",
+		"idx_tup_fetch",
+	}
+
+	mock.ExpectQuery(sanitizeQuery(statUserIndexesQuery(cols))).WillReturnRows(rows)
+
+	ch := make(chan prometheus.Metric)
+	go func() {
+		defer close(ch)
+		c := PGStatUserIndexesCollector{}
+
+		if err := c.Update(context.Background(), inst, ch); err != nil {
+			t.Errorf("Error calling PGStatUserIndexesCollector.Update: %s", err)
+		}
+	}()
+
+	expected := []MetricResult{
+		{labels: labelMap{"datname": "postgres", "indexrelname": "pgtest_accounts_pkey", "schemaname": "public", "relname": "pgtest_accounts"}, value: 8, metricType: dto.MetricType_COUNTER},
+		{labels: labelMap{"datname": "postgres", "indexrelname": "pgtest_accounts_pkey", "schemaname": "public", "relname": "pgtest_accounts"}, value: 9, metricType: dto.MetricType_COUNTER},
+		{labels: labelMap{"datname": "postgres", "indexrelname": "pgtest_accounts_pkey", "schemaname": "public", "relname": "pgtest_accounts"}, value: 5, metricType: dto.MetricType_COUNTER},
+	}
+	convey.Convey("Metrics comparison", t, func() {
+		for _, expect := range expected {
+			m := readMetric(<-ch)
+			convey.So(expect, convey.ShouldResemble, m)
+		}
+	})
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("there were unfulfilled exceptions: %s", err)
+	}
+}