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Add support for pg_stat_checkpointer
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n-rodriguez committed Oct 28, 2024
1 parent a052d93 commit 429fd78
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221 changes: 221 additions & 0 deletions collector/pg_stat_checkpointer.go
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// Copyright 2021 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"

"github.com/prometheus/client_golang/prometheus"
)

const statCheckpointerSubsystem = "stat_checkpointer"

func init() {
// WARNING:
// Disabled by default because this set of metrics is only available from Postgres 17
registerCollector(statCheckpointerSubsystem, defaultDisabled, NewPGStatCheckpointerCollector)
}

type PGStatCheckpointerCollector struct {
}

func NewPGStatCheckpointerCollector(collectorConfig) (Collector, error) {
return &PGStatCheckpointerCollector{}, nil
}

var (
statCheckpointerNumTimedDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statCheckpointerSubsystem, "num_timed_total"),
"Number of scheduled checkpoints due to timeout",
[]string{},
prometheus.Labels{},
)
statCheckpointerNumRequestedDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statCheckpointerSubsystem, "num_requested_total"),
"Number of requested checkpoints that have been performed",
[]string{},
prometheus.Labels{},
)
statCheckpointerRestartpointsTimedDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statCheckpointerSubsystem, "restartpoints_timed_total"),
"Number of scheduled restartpoints due to timeout or after a failed attempt to perform it",
[]string{},
prometheus.Labels{},
)
statCheckpointerRestartpointsReqDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statCheckpointerSubsystem, "restartpoints_req_total"),
"Number of requested restartpoints",
[]string{},
prometheus.Labels{},
)
statCheckpointerRestartpointsDoneDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statCheckpointerSubsystem, "restartpoints_done_total"),
"Number of restartpoints that have been performed",
[]string{},
prometheus.Labels{},
)
statCheckpointerWriteTimeDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statCheckpointerSubsystem, "write_time_total"),
"Total amount of time that has been spent in the portion of processing checkpoints and restartpoints where files are written to disk, in milliseconds",
[]string{},
prometheus.Labels{},
)
statCheckpointerSyncTimeDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statCheckpointerSubsystem, "sync_time_total"),
"Total amount of time that has been spent in the portion of processing checkpoints and restartpoints where files are synchronized to disk, in milliseconds",
[]string{},
prometheus.Labels{},
)
statCheckpointerBuffersWrittenDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statCheckpointerSubsystem, "buffers_written_total"),
"Number of buffers written during checkpoints and restartpoints",
[]string{},
prometheus.Labels{},
)
statCheckpointerStatsResetDesc = prometheus.NewDesc(
prometheus.BuildFQName(namespace, statCheckpointerSubsystem, "stats_reset_total"),
"Time at which these statistics were last reset",
[]string{},
prometheus.Labels{},
)

statCheckpointerQuery = `SELECT
num_timed
,num_requested
,restartpoints_timed
,restartpoints_req
,restartpoints_done
,write_time
,sync_time
,buffers_written
,stats_reset
FROM pg_stat_checkpointer;`
)

func (PGStatCheckpointerCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
db := instance.getDB()
row := db.QueryRowContext(ctx, statCheckpointerQuery)

// num_timed = nt = bigint
// num_requested = nr = bigint
// restartpoints_timed = rpt = bigint
// restartpoints_req = rpr = bigint
// restartpoints_done = rpd = bigint
// write_time = wt = double precision
// sync_time = st = double precision
// buffers_written = bw = bigint
// stats_reset = sr = timestamp

var nt, nr, rpt, rpr, rpd, bw sql.NullInt64
var wt, st sql.NullFloat64
var sr sql.NullTime

err := row.Scan(&nt, &nr, &rpt, &rpr, &rpd, &wt, &st, &bw, &sr)
if err != nil {
return err
}

ntMetric := 0.0
if nt.Valid {
ntMetric = float64(nt.Int64)
}
ch <- prometheus.MustNewConstMetric(
statCheckpointerNumTimedDesc,
prometheus.CounterValue,
ntMetric,
)

nrMetric := 0.0
if nr.Valid {
nrMetric = float64(nr.Int64)
}
ch <- prometheus.MustNewConstMetric(
statCheckpointerNumRequestedDesc,
prometheus.CounterValue,
nrMetric,
)

rptMetric := 0.0
if rpt.Valid {
rptMetric = float64(rpt.Int64)
}
ch <- prometheus.MustNewConstMetric(
statCheckpointerRestartpointsTimedDesc,
prometheus.CounterValue,
rptMetric,
)

rprMetric := 0.0
if rpr.Valid {
rprMetric = float64(rpr.Int64)
}
ch <- prometheus.MustNewConstMetric(
statCheckpointerRestartpointsReqDesc,
prometheus.CounterValue,
rprMetric,
)

rpdMetric := 0.0
if rpd.Valid {
rpdMetric = float64(rpd.Int64)
}
ch <- prometheus.MustNewConstMetric(
statCheckpointerRestartpointsDoneDesc,
prometheus.CounterValue,
rpdMetric,
)

wtMetric := 0.0
if wt.Valid {
wtMetric = float64(wt.Float64)
}
ch <- prometheus.MustNewConstMetric(
statCheckpointerWriteTimeDesc,
prometheus.CounterValue,
wtMetric,
)

stMetric := 0.0
if st.Valid {
stMetric = float64(st.Float64)
}
ch <- prometheus.MustNewConstMetric(
statCheckpointerSyncTimeDesc,
prometheus.CounterValue,
stMetric,
)

bwMetric := 0.0
if bw.Valid {
bwMetric = float64(bw.Int64)
}
ch <- prometheus.MustNewConstMetric(
statCheckpointerBuffersWrittenDesc,
prometheus.CounterValue,
bwMetric,
)

srMetric := 0.0
if sr.Valid {
srMetric = float64(sr.Time.Unix())
}
ch <- prometheus.MustNewConstMetric(
statCheckpointerStatsResetDesc,
prometheus.CounterValue,
srMetric,
)

return nil
}
143 changes: 143 additions & 0 deletions collector/pg_stat_checkpointer_test.go
Original file line number Diff line number Diff line change
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// 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"
"time"

"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 TestPGStatCheckpointerCollector(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{
"num_timed",
"num_requested",
"restartpoints_timed",
"restartpoints_req",
"restartpoints_done",
"write_time",
"sync_time",
"buffers_written",
"stats_reset"}

srT, err := time.Parse("2006-01-02 15:04:05.00000-07", "2023-05-25 17:10:42.81132-07")
if err != nil {
t.Fatalf("Error parsing time: %s", err)
}

rows := sqlmock.NewRows(columns).
AddRow(354, 4945, 289097744, 1242257, int64(3275602074), 89320867, 450139, 2034563757, srT)
mock.ExpectQuery(sanitizeQuery(statCheckpointerQuery)).WillReturnRows(rows)

ch := make(chan prometheus.Metric)
go func() {
defer close(ch)
c := PGStatCheckpointerCollector{}

if err := c.Update(context.Background(), inst, ch); err != nil {
t.Errorf("Error calling PGStatCheckpointerCollector.Update: %s", err)
}
}()

expected := []MetricResult{
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 354},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 4945},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 289097744},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 1242257},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 3275602074},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 89320867},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 450139},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 2034563757},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 1685059842},
}

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)
}
}

func TestPGStatCheckpointerCollectorNullValues(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{
"num_timed",
"num_requested",
"restartpoints_timed",
"restartpoints_req",
"restartpoints_done",
"write_time",
"sync_time",
"buffers_written",
"stats_reset"}

rows := sqlmock.NewRows(columns).
AddRow(nil, nil, nil, nil, nil, nil, nil, nil, nil)
mock.ExpectQuery(sanitizeQuery(statCheckpointerQuery)).WillReturnRows(rows)

ch := make(chan prometheus.Metric)
go func() {
defer close(ch)
c := PGStatCheckpointerCollector{}

if err := c.Update(context.Background(), inst, ch); err != nil {
t.Errorf("Error calling PGStatCheckpointerCollector.Update: %s", err)
}
}()

expected := []MetricResult{
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
{labels: labelMap{}, metricType: dto.MetricType_COUNTER, value: 0},
}

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)
}
}

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