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queries.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 main
import (
"errors"
"fmt"
"github.com/blang/semver/v4"
"github.com/go-kit/log/level"
"gopkg.in/yaml.v2"
)
// UserQuery represents a user defined query
type UserQuery struct {
Query string `yaml:"query"`
Metrics []Mapping `yaml:"metrics"`
Master bool `yaml:"master"` // Querying only for master database
CacheSeconds uint64 `yaml:"cache_seconds"` // Number of seconds to cache the namespace result metrics for.
RunOnServer string `yaml:"runonserver"` // Querying to run on which server version
}
// UserQueries represents a set of UserQuery objects
type UserQueries map[string]UserQuery
// OverrideQuery 's are run in-place of simple namespace look ups, and provide
// advanced functionality. But they have a tendency to postgres version specific.
// There aren't too many versions, so we simply store customized versions using
// the semver matching we do for columns.
type OverrideQuery struct {
versionRange semver.Range
query string
}
// Overriding queries for namespaces above.
// TODO: validate this is a closed set in tests, and there are no overlaps
var queryOverrides = map[string][]OverrideQuery{
"pg_stat_replication": {
{
semver.MustParseRange(">=10.0.0"),
`
SELECT *,
(case pg_is_in_recovery() when 't' then pg_last_wal_receive_lsn() else pg_current_wal_lsn() end) AS pg_current_wal_lsn,
(case pg_is_in_recovery() when 't' then pg_wal_lsn_diff(pg_last_wal_receive_lsn(), pg_lsn('0/0'))::float else pg_wal_lsn_diff(pg_current_wal_lsn(), pg_lsn('0/0'))::float end) AS pg_current_wal_lsn_bytes,
(case pg_is_in_recovery() when 't' then pg_wal_lsn_diff(pg_last_wal_receive_lsn(), replay_lsn)::float else pg_wal_lsn_diff(pg_current_wal_lsn(), replay_lsn)::float end) AS pg_wal_lsn_diff
FROM pg_stat_replication
`,
},
{
semver.MustParseRange(">=9.2.0 <10.0.0"),
`
SELECT *,
(case pg_is_in_recovery() when 't' then pg_last_xlog_receive_location() else pg_current_xlog_location() end) AS pg_current_xlog_location,
(case pg_is_in_recovery() when 't' then pg_xlog_location_diff(pg_last_xlog_receive_location(), replay_location)::float else pg_xlog_location_diff(pg_current_xlog_location(), replay_location)::float end) AS pg_xlog_location_diff
FROM pg_stat_replication
`,
},
{
semver.MustParseRange("<9.2.0"),
`
SELECT *,
(case pg_is_in_recovery() when 't' then pg_last_xlog_receive_location() else pg_current_xlog_location() end) AS pg_current_xlog_location
FROM pg_stat_replication
`,
},
},
"pg_replication_slots": {
{
semver.MustParseRange(">=9.4.0 <10.0.0"),
`
SELECT slot_name, database, active,
(case pg_is_in_recovery() when 't' then pg_xlog_location_diff(pg_last_xlog_receive_location(), restart_lsn) else pg_xlog_location_diff(pg_current_xlog_location(), restart_lsn) end) as pg_xlog_location_diff
FROM pg_replication_slots
`,
},
{
semver.MustParseRange(">=10.0.0"),
`
SELECT slot_name, database, active,
(case pg_is_in_recovery() when 't' then pg_wal_lsn_diff(pg_last_wal_receive_lsn(), restart_lsn) else pg_wal_lsn_diff(pg_current_wal_lsn(), restart_lsn) end) as pg_wal_lsn_diff
FROM pg_replication_slots
`,
},
},
"pg_stat_archiver": {
{
semver.MustParseRange(">=9.4.0"),
`
SELECT *,
extract(epoch from now() - last_archived_time) AS last_archive_age
FROM pg_stat_archiver
`,
},
},
"pg_stat_activity": {
// This query only works
{
semver.MustParseRange(">=9.2.0"),
`
SELECT
pg_database.datname,
tmp.state,
tmp2.usename,
tmp2.application_name,
COALESCE(count,0) as count,
COALESCE(max_tx_duration,0) as max_tx_duration
FROM
(
VALUES ('active'),
('idle'),
('idle in transaction'),
('idle in transaction (aborted)'),
('fastpath function call'),
('disabled')
) AS tmp(state) CROSS JOIN pg_database
LEFT JOIN
(
SELECT
datname,
state,
usename,
application_name,
count(*) AS count,
MAX(EXTRACT(EPOCH FROM now() - xact_start))::float AS max_tx_duration
FROM pg_stat_activity GROUP BY datname,state,usename,application_name) AS tmp2
ON tmp.state = tmp2.state AND pg_database.datname = tmp2.datname
`,
},
{
semver.MustParseRange("<9.2.0"),
`
SELECT
datname,
'unknown' AS state,
usename,
application_name,
COALESCE(count(*),0) AS count,
COALESCE(MAX(EXTRACT(EPOCH FROM now() - xact_start))::float,0) AS max_tx_duration
FROM pg_stat_activity GROUP BY datname,usename,application_name
`,
},
},
}
// Convert the query override file to the version-specific query override file
// for the exporter.
func makeQueryOverrideMap(pgVersion semver.Version, queryOverrides map[string][]OverrideQuery) map[string]string {
resultMap := make(map[string]string)
for name, overrideDef := range queryOverrides {
// Find a matching semver. We make it an error to have overlapping
// ranges at test-time, so only 1 should ever match.
matched := false
for _, queryDef := range overrideDef {
if queryDef.versionRange(pgVersion) {
resultMap[name] = queryDef.query
matched = true
break
}
}
if !matched {
level.Warn(logger).Log("msg", "No query matched override, disabling metric space", "name", name)
resultMap[name] = ""
}
}
return resultMap
}
func parseUserQueries(content []byte) (map[string]intermediateMetricMap, map[string]string, error) {
var userQueries UserQueries
err := yaml.Unmarshal(content, &userQueries)
if err != nil {
return nil, nil, err
}
// Stores the loaded map representation
metricMaps := make(map[string]intermediateMetricMap)
newQueryOverrides := make(map[string]string)
for metric, specs := range userQueries {
level.Debug(logger).Log("msg", "New user metric namespace from YAML metric", "metric", metric, "cache_seconds", specs.CacheSeconds)
newQueryOverrides[metric] = specs.Query
metricMap, ok := metricMaps[metric]
if !ok {
// Namespace for metric not found - add it.
newMetricMap := make(map[string]ColumnMapping)
metricMap = intermediateMetricMap{
columnMappings: newMetricMap,
master: specs.Master,
cacheSeconds: specs.CacheSeconds,
}
metricMaps[metric] = metricMap
}
for _, metric := range specs.Metrics {
for name, mappingOption := range metric {
var columnMapping ColumnMapping
tmpUsage, _ := stringToColumnUsage(mappingOption.Usage)
columnMapping.usage = tmpUsage
columnMapping.description = mappingOption.Description
// TODO: we should support cu
columnMapping.mapping = nil
// Should we support this for users?
columnMapping.supportedVersions = nil
metricMap.columnMappings[name] = columnMapping
}
}
}
return metricMaps, newQueryOverrides, nil
}
// Add queries to the builtinMetricMaps and queryOverrides maps. Added queries do not
// respect version requirements, because it is assumed that the user knows
// what they are doing with their version of postgres.
//
// This function modifies metricMap and queryOverrideMap to contain the new
// queries.
// TODO: test code for all cu.
// TODO: the YAML this supports is "non-standard" - we should move away from it.
func addQueries(content []byte, pgVersion semver.Version, server *Server) error {
metricMaps, newQueryOverrides, err := parseUserQueries(content)
if err != nil {
return err
}
// Convert the loaded metric map into exporter representation
partialExporterMap := makeDescMap(pgVersion, server.labels, metricMaps)
// Merge the two maps (which are now quite flatteend)
for k, v := range partialExporterMap {
_, found := server.metricMap[k]
if found {
level.Debug(logger).Log("msg", "Overriding metric from user YAML file", "metric", k)
} else {
level.Debug(logger).Log("msg", "Adding new metric from user YAML file", "metric", k)
}
server.metricMap[k] = v
}
// Merge the query override map
for k, v := range newQueryOverrides {
_, found := server.queryOverrides[k]
if found {
level.Debug(logger).Log("msg", "Overriding query override from user YAML file", "query_override", k)
} else {
level.Debug(logger).Log("msg", "Adding new query override from user YAML file", "query_override", k)
}
server.queryOverrides[k] = v
}
return nil
}
func queryDatabases(server *Server) ([]string, error) {
rows, err := server.db.Query("SELECT datname FROM pg_database WHERE datallowconn = true AND datistemplate = false AND datname != current_database()")
if err != nil {
return nil, fmt.Errorf("Error retrieving databases: %v", err)
}
defer rows.Close() // nolint: errcheck
var databaseName string
result := make([]string, 0)
for rows.Next() {
err = rows.Scan(&databaseName)
if err != nil {
return nil, errors.New(fmt.Sprintln("Error retrieving rows:", err))
}
result = append(result, databaseName)
}
return result, nil
}