1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
// 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"
"log/slog"
"github.com/blang/semver/v4"
"github.com/prometheus/client_golang/prometheus"
)
const xlogLocationSubsystem = "xlog_location"
func init() {
registerCollector(xlogLocationSubsystem, defaultDisabled, NewPGXlogLocationCollector)
}
type PGXlogLocationCollector struct {
log *slog.Logger
}
func NewPGXlogLocationCollector(config collectorConfig) (Collector, error) {
return &PGXlogLocationCollector{log: config.logger}, nil
}
var (
xlogLocationBytes = prometheus.NewDesc(
prometheus.BuildFQName(namespace, xlogLocationSubsystem, "bytes"),
"Postgres LSN (log sequence number) being generated on primary or replayed on replica (truncated to low 52 bits)",
[]string{},
prometheus.Labels{},
)
xlogLocationQuery = `
SELECT CASE
WHEN pg_is_in_recovery() THEN (pg_last_xlog_replay_location() - '0/0') % (2^52)::bigint
ELSE (pg_current_xlog_location() - '0/0') % (2^52)::bigint
END AS bytes
`
)
func (c PGXlogLocationCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
db := instance.getDB()
// xlog was renmaed to WAL in PostgreSQL 10
// https://wiki.postgresql.org/wiki/New_in_postgres_10#Renaming_of_.22xlog.22_to_.22wal.22_Globally_.28and_location.2Flsn.29
after10 := instance.version.Compare(semver.MustParse("10.0.0"))
if after10 >= 0 {
c.log.Warn("xlog_location collector is not available on PostgreSQL >= 10.0.0, skipping")
return nil
}
rows, err := db.QueryContext(ctx,
xlogLocationQuery)
if err != nil {
return err
}
defer rows.Close()
for rows.Next() {
var bytes float64
if err := rows.Scan(&bytes); err != nil {
return err
}
ch <- prometheus.MustNewConstMetric(
xlogLocationBytes,
prometheus.GaugeValue,
bytes,
)
}
if err := rows.Err(); err != nil {
return err
}
return nil
}
|
