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pgm.go
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pgm.go
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package main
import (
"context"
"flag"
"fmt"
"net/url"
"os"
"os/signal"
"strings"
"syscall"
"time"
"github.com/jackc/pgx/v5"
)
type Query struct {
Table string
SQL string
Tags []string
}
var (
Queries = []*Query{
&Query{
Table: "pg_db_stats",
Tags: []string{},
SQL: `
select
numbackends,
xact_commit,
xact_rollback,
blks_read,
blks_hit,
tup_returned,
tup_fetched,
tup_inserted,
tup_updated,
tup_deleted,
conflicts,
temp_files,
temp_bytes,
deadlocks,
blk_read_time,
blk_write_time,
extract(epoch from (now() - pg_postmaster_start_time()))::int8
as postmaster_uptime_s,
extract(epoch from (now() - pg_backup_start_time()))::int8
as backup_duration_s,
case when pg_is_in_recovery() then 1 else 0 end
as in_recovery_int
from
pg_stat_database, pg_control_system()
where
datname = current_database();
`,
},
&Query{
Table: "pg_index_stats",
Tags: []string{"table_name", "schema", "index_name"},
SQL: `
WITH q_locked_rels AS (
select relation from pg_locks where mode = 'AccessExclusiveLock' and granted
)
SELECT
schemaname::text as schema,
indexrelname::text as index_name,
relname::text as table_name,
coalesce(idx_scan, 0) as idx_scan,
coalesce(idx_tup_read, 0) as idx_tup_read,
coalesce(idx_tup_fetch, 0) as idx_tup_fetch,
coalesce(pg_relation_size(indexrelid), 0) as index_size_b,
quote_ident(schemaname)||'.'||quote_ident(sui.indexrelname) as index_full_name_val,
case when not i.indisvalid then 1 else 0 end as is_invalid_int,
case when i.indisprimary then 1 else 0 end as is_pk_int,
case when i.indisunique or indisexclusion then 1 else 0 end as is_uq_or_exc
FROM
pg_stat_user_indexes sui
JOIN
pg_index i USING (indexrelid)
WHERE
NOT schemaname like E'pg\\_temp%'
AND i.indrelid not in (select relation from q_locked_rels)
AND i.indexrelid not in (select relation from q_locked_rels)
ORDER BY
schemaname, relname, indexrelname;
`,
},
&Query{
Table: "pg_locks_mode",
Tags: []string{"lockmode"},
SQL: `
WITH q_locks AS (
select
*
from
pg_locks
where
pid != pg_backend_pid()
and database = (select oid from pg_database where datname = current_database())
)
SELECT
lockmodes AS lockmode,
coalesce((select count(*) FROM q_locks WHERE mode = lockmodes), 0) AS count
FROM
unnest('{AccessShareLock, ExclusiveLock, RowShareLock, RowExclusiveLock, ShareLock, ShareRowExclusiveLock, AccessExclusiveLock, ShareUpdateExclusiveLock}'::text[]) lockmodes;
`,
},
&Query{
Table: "pg_table_stats",
Tags: []string{"table_name", "schema"},
SQL: `
select
quote_ident(schemaname) as schema,
quote_ident(ut.relname) as table_name,
pg_table_size(relid) as table_size_b,
abs(greatest(ceil(log((pg_table_size(relid)+1) / 10^6)), 0))::text
as table_size_cardinality_mb, -- i.e. 0=<1MB, 1=<10MB, 2=<100MB,..
pg_total_relation_size(relid) as total_relation_size_b,
case when reltoastrelid != 0
then pg_total_relation_size(reltoastrelid)
else 0::int8 end as toast_size_b,
(extract(epoch from now() - greatest(last_vacuum, last_autovacuum)))::int8
as seconds_since_last_vacuum,
(extract(epoch from now() - greatest(last_analyze, last_autoanalyze)))::int8
as seconds_since_last_analyze,
case when 'autovacuum_enabled=off' = ANY(c.reloptions) then 1 else 0 end
as no_autovacuum,
seq_scan,
seq_tup_read,
coalesce(idx_scan, 0) as idx_scan,
coalesce(idx_tup_fetch, 0) as idx_tup_fetch,
n_tup_ins,
n_tup_upd,
n_tup_del,
n_tup_hot_upd,
n_live_tup,
n_dead_tup,
vacuum_count,
autovacuum_count,
analyze_count,
autoanalyze_count,
age(relfrozenxid) as tx_freeze_age,
relpersistence
from
pg_stat_user_tables ut
join
pg_class c on c.oid = ut.relid
where
-- leaving out fully locked tables as pg_relation_size
-- also wants a lock and would wait
not exists (select 1 from pg_locks where relation = relid
and mode = 'AccessExclusiveLock' and granted)
and c.relpersistence != 't'; -- and temp tables
`,
},
&Query{
Table: "pg_backends",
Tags: []string{},
SQL: `
with sa_snapshot as (
select * from pg_stat_activity
where datname = current_database()
and not query like 'autovacuum:%'
and pid != pg_backend_pid()
)
select
(select count(*) from sa_snapshot) as total,
(select count(*) from pg_stat_activity
where pid != pg_backend_pid()) as instance_total,
current_setting('max_connections')::int as max_connections,
(select count(*) from sa_snapshot where state = 'active') as active,
(select count(*) from sa_snapshot where state = 'idle') as idle,
(select count(*) from sa_snapshot
where state = 'idle in transaction') as idleintransaction,
(select count(*) from sa_snapshot
where wait_event_type in ('LWLockNamed', 'Lock', 'BufferPin'))
as waiting,
(select extract(epoch from max(now() - query_start))::int
from sa_snapshot where wait_event_type
in ('LWLockNamed', 'Lock', 'BufferPin'))
as longest_waiting_seconds,
(select extract(epoch from (now() - backend_start))::int
from sa_snapshot order by backend_start limit 1)
as longest_session_seconds,
(select extract(epoch from (now() - xact_start))::int
from sa_snapshot where xact_start is not null
order by xact_start limit 1) as longest_tx_seconds,
(select extract(epoch from (now() - xact_start))::int
from pg_stat_activity where query like 'autovacuum:%'
order by xact_start limit 1) as longest_autovacuum_seconds,
(select extract(epoch from max(now() - query_start))::int
from sa_snapshot where state = 'active') as longest_query_seconds,
(select max(age(backend_xmin))::int8 from sa_snapshot)
as max_xmin_age_tx,
(select count(*) from pg_stat_activity
where datname = current_database()
and query like 'autovacuum:%') as av_workers;
`,
},
}
)
type Row struct {
Measure string
Tags map[string]interface{}
Fields map[string]interface{}
}
type Gathered struct {
Rows []*Row
}
func (g *Gathered) Combine(o *Gathered) *Gathered {
g.Rows = append(g.Rows, o.Rows...)
return g
}
func (g *Gathered) Write(now int64, db string) error {
for _, row := range g.Rows {
fmt.Printf("%v", row.Measure)
fmt.Printf(",datname=%s", db)
for key, value := range row.Tags {
fmt.Printf(",%v=%v", key, value)
}
first := true
for key, value := range row.Fields {
if first {
fmt.Printf(" ")
first = false
} else {
fmt.Printf(",")
}
switch v := value.(type) {
case string:
fmt.Printf("%v=\"%v\"", key, strings.ReplaceAll(v, "\"", ""))
default:
fmt.Printf("%v=%v", key, value)
}
}
fmt.Printf(" %v\n", now)
}
return nil
}
func gatherQuery(ctx context.Context, o *options, conn *pgx.Conn, query *Query) (*Gathered, error) {
q, err := conn.Query(ctx, query.SQL)
if err != nil {
return nil, err
}
defer q.Close()
tags := make(map[string]bool)
for _, tag := range query.Tags {
tags[tag] = true
}
rows := make([]*Row, 0)
for q.Next() {
values, err := q.Values()
if err != nil {
return nil, err
}
row := &Row{
Measure: query.Table,
Tags: make(map[string]interface{}),
Fields: make(map[string]interface{}),
}
for key, value := range o.ParsedTags() {
row.Tags[key] = value
}
for i, column := range q.FieldDescriptions() {
name := string(column.Name)
if values[i] != nil {
if ok := tags[name]; ok {
row.Tags[name] = values[i]
} else {
row.Fields[name] = values[i]
}
}
}
rows = append(rows, row)
}
return &Gathered{Rows: rows}, nil
}
func queryStringArray(ctx context.Context, conn *pgx.Conn, sql string) ([]string, error) {
rows, err := conn.Query(ctx, sql)
if err != nil {
return nil, err
}
defer rows.Close()
values := []string{}
for rows.Next() {
var name string
rows.Scan(&name)
values = append(values, name)
}
if err := rows.Err(); err != nil {
return nil, err
}
return values, nil
}
func databaseNames(ctx context.Context, o *options) ([]string, error) {
conn, err := pgx.Connect(ctx, o.URL)
if err != nil {
return nil, fmt.Errorf("(db-conn): %v", err)
}
defer conn.Close(ctx)
return queryStringArray(ctx, conn, "SELECT datname FROM pg_database where datistemplate = false")
}
func tableNames(ctx context.Context, conn *pgx.Conn) ([]string, error) {
return queryStringArray(ctx, conn, "SELECT tablename FROM pg_catalog.pg_tables WHERE schemaname != 'pg_catalog' AND schemaname != 'information_schema'")
}
func gatherQueries(ctx context.Context, o *options, conn *pgx.Conn, queries []*Query) (*Gathered, error) {
g := &Gathered{}
for _, query := range queries {
if gathered, err := gatherQuery(ctx, o, conn, query); err != nil {
return nil, fmt.Errorf("(db-query) %v: %v", query.SQL, err)
} else {
g = g.Combine(gathered)
}
}
return g, nil
}
func gatherGueJobs(ctx context.Context, o *options, conn *pgx.Conn) (*Gathered, error) {
queries := []*Query{
&Query{
Table: "pg_gue_jobs",
Tags: []string{"job_type", "queue"},
SQL: `
SELECT
CASE WHEN queue = '' THEN 'none' ELSE queue END AS queue,
job_type, COUNT(*) AS queue_length,
EXTRACT(EPOCH FROM NOW() - MIN(created_at)) AS oldest_age,
EXTRACT(EPOCH FROM NOW() - MAX(created_at)) AS newest_age
FROM gue_jobs
WHERE run_at < NOW()
GROUP BY queue, job_type;
`,
},
&Query{
Table: "pg_gue_job_errors",
Tags: []string{"job_type", "queue"},
SQL: `
SELECT
CASE WHEN queue = '' THEN 'none' ELSE queue END AS queue,
job_type, COUNT(*) AS error_length
FROM gue_jobs
WHERE run_at > NOW()
GROUP BY queue, job_type;
`,
},
}
return gatherQueries(ctx, o, conn, queries)
}
func gatherSpecials(ctx context.Context, o *options, conn *pgx.Conn) (*Gathered, error) {
tables, err := tableNames(ctx, conn)
if err != nil {
return nil, err
}
g := &Gathered{}
for _, table := range tables {
if table == "gue_jobs" {
if more, err := gatherGueJobs(ctx, o, conn); err != nil {
return nil, err
} else {
g = g.Combine(more)
}
}
}
return g, nil
}
func gather(ctx context.Context, o *options) error {
dbs, err := databaseNames(ctx, o)
if err != nil {
return fmt.Errorf("(db-names): %v", err)
}
parsed, err := url.Parse(o.URL)
if err != nil {
return fmt.Errorf("(db-url): %v", err)
}
excluded := make(map[string]bool)
for _, name := range strings.Split(o.Exclude, ",") {
excluded[name] = true
}
for _, db := range dbs {
if excluded[db] {
continue
}
parsed.Path = db
conn, err := pgx.Connect(ctx, parsed.String())
if err != nil {
return fmt.Errorf("(db-conn): %v", err)
}
defer conn.Close(ctx)
now := time.Now().UTC().UnixNano()
for _, query := range Queries {
if gathered, err := gatherQuery(ctx, o, conn, query); err != nil {
return fmt.Errorf("(db-query) %v: %v", query.SQL, err)
} else {
if err := gathered.Write(now, db); err != nil {
return err
}
}
}
if gathered, err := gatherSpecials(ctx, o, conn); err != nil {
return fmt.Errorf("(db-special): %v", err)
} else {
if err := gathered.Write(now, db); err != nil {
return err
}
}
}
return nil
}
type options struct {
URL string
Once bool
Exclude string
Tags string
}
func (o *options) ParsedTags() map[string]string {
parsed := make(map[string]string)
expressions := strings.Split(o.Tags, ",")
for _, expression := range expressions {
maybePair := strings.Split(expression, "=")
if len(maybePair) == 2 {
parsed[maybePair[0]] = maybePair[1]
}
}
return parsed
}
func main() {
o := &options{
URL: os.Getenv("DATABASE_URL"),
}
flag.BoolVar(&o.Once, "once", false, "run once")
flag.StringVar(&o.Tags, "tags", "pgm", "tags")
flag.StringVar(&o.Exclude, "exclude", "rdsadmin", "Exclude")
flag.Parse()
ctx := context.Background()
if o.Once {
if err := gather(ctx, o); err != nil {
panic(err)
}
return
}
c := make(chan os.Signal, 1)
signal.Notify(c, syscall.SIGHUP)
for {
<-c
if err := gather(ctx, o); err != nil {
panic(err)
}
}
}