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PMM-13448 Support PG17 to provide pre PG17 metrics support. #281

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merged 1 commit into from
Nov 27, 2024
Merged

PMM-13448 Support PG17 to provide pre PG17 metrics support. #281

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53 changes: 44 additions & 9 deletions collector/pg_stat_bgwriter.go
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ package collector
import (
"context"
"database/sql"

"github.com/blang/semver/v4"
"github.com/prometheus/client_golang/prometheus"
)

Expand Down Expand Up @@ -170,7 +170,7 @@ var statBGWriter = map[string]*prometheus.Desc{
),
}

const statBGWriterQuery = `SELECT
const statBGWriterQueryPrePG17 = `SELECT
checkpoints_timed
,checkpoints_req
,checkpoint_write_time
Expand All @@ -184,19 +184,55 @@ const statBGWriterQuery = `SELECT
,stats_reset
FROM pg_stat_bgwriter;`

func (PGStatBGWriterCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
const statBGWriterQueryPost17 = `SELECT
buffers_clean
,maxwritten_clean
,buffers_alloc
,stats_reset
FROM pg_stat_bgwriter;`

const 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 (p PGStatBGWriterCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
db := instance.getDB()
row := db.QueryRowContext(ctx,
statBGWriterQuery)

var cpt, cpr, bcp, bc, mwc, bb, bbf, ba sql.NullInt64
var cpwt, cpst sql.NullFloat64
var sr sql.NullTime

err := row.Scan(&cpt, &cpr, &cpwt, &cpst, &bcp, &bc, &mwc, &bb, &bbf, &ba, &sr)
if err != nil {
return err
if instance.version.GE(semver.MustParse("17.0.0")) {
row := db.QueryRowContext(ctx,
statBGWriterQueryPost17)
err := row.Scan(&bc, &mwc, &ba, &sr)
if err != nil {
return err
}
var rpt, rpr, rpd sql.NullInt64
var csr sql.NullTime
// these variables are not used, but I left them here for reference
row = db.QueryRowContext(ctx,
statCheckpointerQuery)
err = row.Scan(&cpt, &cpr, &rpt, &rpr, &rpd, &cpwt, &cpst, &bcp, &csr)
if err != nil {
return err
}
} else {
row := db.QueryRowContext(ctx,
statBGWriterQueryPrePG17)
err := row.Scan(&cpt, &cpr, &cpwt, &cpst, &bcp, &bc, &mwc, &bb, &bbf, &ba, &sr)
if err != nil {
return err
}
}

cptMetric := 0.0
Expand Down Expand Up @@ -400,6 +436,5 @@ func (PGStatBGWriterCollector) Update(ctx context.Context, instance *instance, c
"exporter",
instance.name,
)

return nil
}
4 changes: 2 additions & 2 deletions collector/pg_stat_bgwriter_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@ func TestPGStatBGWriterCollector(t *testing.T) {

rows := sqlmock.NewRows(columns).
AddRow(354, 4945, 289097744, 1242257, int64(3275602074), 89320867, 450139, 2034563757, 0, int64(2725688749), srT)
mock.ExpectQuery(sanitizeQuery(statBGWriterQuery)).WillReturnRows(rows)
mock.ExpectQuery(sanitizeQuery(statBGWriterQueryPrePG17)).WillReturnRows(rows)
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Should we cover this change with unit tests for PG >= 17 as well?

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it's a temporary solution until we get proper solution from upstream


ch := make(chan prometheus.Metric)
go func() {
Expand Down Expand Up @@ -114,7 +114,7 @@ func TestPGStatBGWriterCollectorNullValues(t *testing.T) {

rows := sqlmock.NewRows(columns).
AddRow(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
mock.ExpectQuery(sanitizeQuery(statBGWriterQuery)).WillReturnRows(rows)
mock.ExpectQuery(sanitizeQuery(statBGWriterQueryPrePG17)).WillReturnRows(rows)

ch := make(chan prometheus.Metric)
go func() {
Expand Down