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michael-todorovicmichael-todorovic
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feat: add support for pg_stat_user_indexes
Signed-off-by: Michael Todorovic <[email protected]>
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‎README.md

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

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

‎collector/pg_stat_user_indexes_test.go

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

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