Slides from Highload 2015 (Moscow, Russia).

1. Deep dive
into
PostgreSQL
Statistics.
Алексей Лесовский

2. О чем доклад
Статистика активности postgresql.
Как эффективно использовать статистику.
Решение проблем на основе данных статистики.
https://goo.gl/d0pSYK

3. Чего НЕ будет
Статистика планировщика запросов.
Обзор инструментов.

4. Итоговая цель
Умение использовать статистику - это полезно.
Статистика в постгресе - это не страшно.
Какую статистику выбрать для решения частной
задачи.

5. Черный ящик
$ ps hf -u postgres -o cmd
/usr/pgsql-9.4/bin/postgres -D /var/lib/pgsql/9.4/data
_ postgres: logger process
_ postgres: checkpointer process
_ postgres: writer process
_ postgres: wal writer process
_ postgres: autovacuum launcher process
_ postgres: stats collector process
_ postgres: postgres pgbench [local] idle in transaction
_ postgres: postgres pgbench [local] idle
_ postgres: postgres pgbench [local] UPDATE
_ postgres: postgres pgbench [local] UPDATE waiting
_ postgres: postgres pgbench [local] UPDATE

6. Как тратится время
Write Ahead Log
Shared
Buffers
Buffers IO Autovacuum Workers
Autovacuum Launcher
Background Workers
Indexes IO
Query Execution
Query Planning
Client Backends Postmaster
Relations IO
Logger Process Stats Collector
Logical
Replication
WAL Sender
Process
Archiver
Process
Background
Writer
Checkpointer
Process
Network Storage
Recovery Process
WAL Receiver Process
Tables/Indexes Data Files

7. Проблемы
Информации много (~109 метрик для 9.4).
Статистика представлена online счетчиками.
Нет истории (но есть функции сброса статистики).
Отсутствие native инструмента.
Множество сторонних инструментов.

8. Проблемы
Информации много (~109 метрик для 9.4).
Статистика представлена online счетчиками.
Нет истории (но есть функции сброса статистики).
Отсутствие native инструмента.
Множество сторонних инструментов.
Важно уметь брать статистику напрямую.
Нужны базовые знания SQL.

9. Что предлагают?
События, происходящие в базе.
Свойства объектов базы (баз, таблиц, индексов).
Время, затраченное событием.

10. Источники статы
Счетчики в shared memory.
Функции.
Встроенные представления (VIEWs).
Официальный пакет contribs.
Неофициальные contrib'ы.

11. Источники статы
pg_stat_all_tables
pg_current_xlog_location()
pg_replication_slots
pg_stat_replication
pg_stat_archiver
pg_stat_database_conflicts
pg_buffercache
pg_stat_database
pg_stat_user_tables
pg_stat_database
pg_stat_bgwrier
pgstattuple
pg_table_size()
pg_database_size
pg_index_size()
pg_stat_activity
EXPLAIN
pg_locks
pg_stat_user_functions
pg_stat_all_indexes
pg_statio_all_indexes
pg_statio_all_tables
pg_xlog_location_diff()
pg_stat_kcache
pg_stat_statements
pg_roles
pg_database
pg_class
pg_relation_size()
pg_total_relation_size()
current_setting()
pg_current_xlog_insert_location()
pg_last_xact_replay_timestamp()
pg_last_xlog_replay_location()
pg_tablespace_size()
pg_ls_dir()

12. Write Ahead Log
Shared
Buffers
Buffers IO Autovacuum Workers
Autovacuum Launcher
Background Workers
Indexes IO
Query Execution
Query Planning
Client Backends Postmaster
Tables IO
Logger Process Stats Collector
Logical
Replication
WAL Sender
Process
Archiver
Process
Background
Writer
Checkpointer
Process
Network Storage
Recovery Process
WAL Receiver Process
Tables/Indexes Data Files
pg_stat_all_tables
pg_current_xlog_location
pg_replication_slots
pg_stat_replication
pg_stat_archiver
pg_stat_database_conflicts
pg_buffercache
pg_stat_database
pg_stat_activity
pg_stat_user_tables
pg_stat_database
pg_stat_bgwrier
pgstattuplepg_table_size
pg_database_size
pg_index_size
pg_stat_activity
EXPLAIN
pg_stat_statements
pg_locks
pg_stat_user_functions
pg_stat_all_indexes
pg_stat_database
pg_statio_all_indexes
pg_statio_all_tables
pg_xlog_location_diff
nicstat* iostat*
pg_stat_kcache
pg_stat_statements

13. pg_stat_database
$ select * from pg_stat_database where datname = 'shop';
-[ RECORD 1 ]--+-------------------------------------------
datid | 16414
datname | shop
numbackends | 34
xact_commit | 51167155051
xact_rollback | 44781878826
blks_read | 7978770895
blks_hit | 9683551077519
tup_returned | 12507331807583
tup_fetched | 3885840966616
tup_inserted | 2898024857
tup_updated | 3082071349
tup_deleted | 2751363323
conflicts | 0
temp_files | 377675
temp_bytes | 4783712399875
deadlocks | 151
blk_read_time | 214344118.089
blk_write_time | 1260880.747
stats_reset | 2015-05-31 11:37:52.017967+03

14. Cache hit ratio
$ select * from pg_stat_database;
...
blks_read | 7978770895
blks_hit | 9683551077519
...
$ select
sum(blks_hit)*100/sum(blks_hit+blks_read) as hit_ratio
from pg_stat_database;
Больше = лучше, но не меньше 90%

15. Аномалии
$ select * from pg_stat_database;
...
xact_commit | 51167155051
xact_rollback | 44781878826
conflicts | 0
temp_files | 377675
temp_bytes | 4783712399875
deadlocks | 151
...
$ select
datname,
(xact_commit*100)/(xact_commit+xact_rollback) as c_ratio,
deadlocks, conflicts,
temp_file, pg_size_pretty(temp_bytes) as temp_size
from pg_stat_database;

16. Аномалии
$ select * from pg_stat_database;
...
xact_commit | 51167155051 < 95 %
xact_rollback | 44781878826 > 5 %
conflicts | 0 > 10
temp_files | 377675 > 100
temp_bytes | 4783712399875 > 10 GB
deadlocks | 151 > 10
...
$ select
datname,
(xact_commit*100)/(xact_commit+xact_rollback) as c_ratio,
deadlocks, conflicts,
temp_file, pg_size_pretty(temp_bytes) as temp_size
from pg_stat_database;

17. pg_stat_bgwriter
$ select * from pg_stat_bgwriter;
-[ RECORD 1 ]---------+------------------------------------
checkpoints_timed | 3267
checkpoints_req | 6
checkpoint_write_time | 10416478591
checkpoint_sync_time | 405039
buffers_checkpoint | 2518065526
buffers_clean | 99602799
maxwritten_clean | 157
buffers_backend | 219356924
buffers_backend_fsync | 0
buffers_alloc | 3477374822
stats_reset | 2015-05-31 11:09:48.413185+03

18. Checkpoint's
$ select * from pg_stat_bgwriter;
...
checkpoints_timed | 3267
checkpoints_req | 6
...
checkpoints_req > checkpoints_timed = плохо
postgresql.conf
●
checkpoint_segments
●
checkpoint_timeout
●
checkpoint_completion_target

19. Background Writer
$ select * from pg_stat_bgwriter;
...
buffers_clean | 99602799
maxwritten_clean | 157 > 0
buffers_backend_fsync | 0 > 0
...
Обеспечивает бэкенды чистыми страницами.
Разгружает checkpointer.
postgresql.conf
●
bgwriter_delay
●
bgwriter_lru_maxpages
●
bgwriter_lru_multiplier

20. pg_stat_replication
$ select * from pg_stat_replication;
-[ RECORD 1 ]----+------------------------------------
pid | 26921
usesysid | 15588142
usename | replica
application_name | walreceiver
client_addr | 10.0.0.7
client_hostname |
client_port | 32956
backend_start | 2015-10-01 19:14:42.979377+03
state | streaming
sent_location | 1691/EEE65900
write_location | 1691/EEE65900
flush_location | 1691/EEE65900
replay_location | 1691/EEE658D0
sync_priority | 0
sync_state | async

21. Лаг репликации
$ select * from pg_stat_replication;
...
sent_location | 1691/EEE65900
write_location | 1691/EEE65900
flush_location | 1691/EEE65900
replay_location | 1691/EEE658D0
...
1692/EEE65900 — позиция в журнале транзакций.
Все значения равны = идеально.

22. Лаг репликации
Причины отставания:
Networking,
Storage,
CPU.
сколько записано xlog в байтах
$ select
pg_xlog_location_diff(pg_current_xlog_location(),'0/00000000');
лаг репликации в байтах
$ select
client_addr,
pg_xlog_location_diff(pg_current_xlog_location(), replay_location)
from pg_stat_replication;
лаг репликации в секундах
$ select
extract(epoch from now() - pg_last_xact_replay_timestamp());

23. pg_stat_all_tables
$ select * from pg_stat_all_tables;
-[ RECORD 1 ]-------+------------------------------------
relid | 98221
schemaname | public
relname | clientsession
seq_scan | 192
seq_tup_read | 364544695
idx_scan | 2691939318
idx_tup_fetch | 2669551448
n_tup_ins | 239532851
n_tup_upd | 736119030
n_tup_del | 239898968
n_tup_hot_upd | 497688344
n_live_tup | 3493472
n_dead_tup | 1606
n_mod_since_analyze | 349526
...

24. Sequential scans
$ select * from pg_stat_all_tables;
...
seq_scan | 192 необязательно плохо
seq_tup_read | 364544695 > 1000 (seq_tup_avg)
...
$ select
relname,
pg_size_pretty(pg_relation_size(relname::regclass)) as size,
seq_scan, seq_tup_read,
seq_scan / seq_tup_read as seq_tup_avg
from pg_stat_user_tables
where seq_tup_read > 0 order by 3,4 desc limit 5;

25. Размеры таблиц
$ select
relname,
pg_size_pretty(pg_total_relation_size(relname::regclass)) as
full_size,
pg_size_pretty(pg_relation_size(relname::regclass)) as
table_size,
pg_size_pretty(pg_total_relation_size(relname::regclass) -
pg_relation_size(relname::regclass)) as index_size
from pg_stat_user_tables
order by pg_total_relation_size(relname::regclass) desc limit 10;
Также есть метакоманды psql: dt+ и di+

26. Write activity
$ select * from pg_stat_all_tables;
...
n_tup_upd | 736119030
n_tup_hot_upd | 497688344
...
UPDATE = DELETE + INSERT
UPDATE = TABLE UPDATE + INDEX UPDATE

27. Write activity
$ select
s.relname,
pg_size_pretty(pg_relation_size(relid)),
coalesce(n_tup_ins,0) + 2 * coalesce(n_tup_upd,0) -
coalesce(n_tup_hot_upd,0) + coalesce(n_tup_del,0) AS total_writes,
(coalesce(n_tup_hot_upd,0)::float * 100 / (case when n_tup_upd > 0
then n_tup_upd else 1 end)::float)::numeric(10,2) AS hot_rate,
(select v[1] FROM regexp_matches(reloptions::text,E'fillfactor=(d+)') as
r(v) limit 1) AS fillfactor
from pg_stat_all_tables s
join pg_class c ON c.oid=relid
order by total_writes desc limit 50;
Что такое Heap-Only Tuples?
HOT не вызывает перестроения индекса.
HOT только для тех значений которые не участвуют в индексе
Большое значение n_tup_hot_upd = хорошо.
Как добиться большого n_tup_hot_upd?

28. Write activity
| pg_size_pretty | total_writes | hot_rate | fillfactor
-+----------------+--------------+----------+------------
| 9418 MB | 391459091 | 5.03 |
| 417 MB | 285948760 | 0.00 |
| 76 MB | 232031972 | 87.31 | 70
| 7123 MB | 124281107 | 99.36 | 70
Fillfactor определяет резерв свободного места в странице.
Накладные расходы на размер таблиц (индексов).
ALTER TABLE table_name SET (fillfactor = 70);

29. Autovacuum queue
$ select c.relname,
current_setting('autovacuum_vacuum_threshold') as av_base_thresh,
current_setting('autovacuum_vacuum_scale_factor') as av_scale_factor,
(current_setting('autovacuum_vacuum_threshold')::int +
(current_setting('autovacuum_vacuum_scale_factor')::float * c.reltuples))
as av_thresh,
s.n_dead_tup
from pg_stat_user_tables s join pg_class c ON s.relname = c.relname
where s.n_dead_tup > (current_setting('autovacuum_vacuum_threshold')::int
+ (current_setting('autovacuum_vacuum_scale_factor')::float * c.reltuples));
| av_base_thresh | av_scale_factor | av_thresh | n_dead_tup
+----------------+-----------------+-----------+------------
| 50 | 0.01 | 60302 | 85445
| 50 | 0.01 | 50 | 1349
| 50 | 0.01 | 55 | 12479
| 50 | 0.01 | 103 | 3134
| 50 | 0.01 | 52716 | 173100

30. Autovacuum queue
$ select c.relname,
current_setting('autovacuum_vacuum_threshold') as av_base_thresh,
current_setting('autovacuum_vacuum_scale_factor') as av_scale_factor,
(current_setting('autovacuum_vacuum_threshold')::int +
(current_setting('autovacuum_vacuum_scale_factor')::float * c.reltuples))
as av_thresh,
s.n_dead_tup
from pg_stat_user_tables s join pg_class c ON s.relname = c.relname
where s.n_dead_tup > (current_setting('autovacuum_vacuum_threshold')::int
+ (current_setting('autovacuum_vacuum_scale_factor')::float * c.reltuples));
| av_base_thresh | av_scale_factor | av_thresh | n_dead_tup
+----------------+-----------------+-----------+------------
| 50 | 0.01 | 60302 | 60545
| 50 | 0.01 | 50 | 1349
| 50 | 0.01 | 55 | 12479
| 50 | 0.01 | 103 | 3134
| 50 | 0.01 | 52716 | 173100
Avito Experience
https://github.com/eshkinkot/avito/blob/master/munin/vacuum_queue

31. pg_stat_all_indexes
$ select * from pg_stat_all_indexes where idx_scan = 0;
-[ RECORD 1 ]-+------------------------------------------
relid | 98242
indexrelid | 55732253
schemaname | public
relname | products
indexrelname | products_special2_idx
idx_scan | 0
idx_tup_read | 0
idx_tup_fetch | 0

32. Лишние индексы
$ select * from pg_stat_all_indexes where idx_scan = 0;
...
indexrelname | products_special2_idx
idx_scan | 0 0 = плохо
...
https://github.com/PostgreSQL-Consulting/pg-utils/blob/master/sql/lo
w_used_indexes.sql
http://www.databasesoup.com/2014/05/new-finding-unused-indexes-q
uery.html

33. Лишние индексы
$ select * from pg_stat_all_indexes where idx_scan = 0;
...
indexrelname | products_special2_idx
idx_scan | 0 0 = плохо
...
https://github.com/PostgreSQL-Consulting/pg-utils/blob/master/sql/lo
w_used_indexes.sql
http://www.databasesoup.com/2014/05/new-finding-unused-indexes-q
uery.html
Неиспользуемые индексы - плохо.
Занимают место.
Замедляют UPDATE, DELETE, INSERT операции.
Лишняя работа для VACUUM.

34. pg_stat_activity
$ select * from pg_stat_activity;
-[ RECORD 1 ]----+--------------------------------------------
datid | 16401
datname | ts
pid | 116408
usesysid | 16384
usename | tsagent
application_name | unicorn_rails worker
client_addr | 172.17.0.37
client_hostname |
client_port | 50888
backend_start | 2015-10-14 15:18:03.01039+00
xact_start |
query_start | 2015-10-14 15:21:30.336325+00
state_change | 2015-10-14 15:21:30.33635+00
waiting | f
state | idle
backend_xid |
backend_xmin |
query | COMMIT

35. Общая активность
$ select * from pg_stat_activity;
...
datname | ts
usename | tsagent
client_addr | 172.17.0.37
...
общий процент подключений
$ select
count(*)*100/(select current_setting('max_connections')::int)
from pg_stat_activity;

36. Общая активность
$ select * from pg_stat_activity;
...
datname | ts
usename | tsagent
client_addr | 172.17.0.37
...
$ select
client_addr, usename, datname, count(*)
from pg_stat_activity group by 1,2,3 order by 4 desc;
client_addr | usename | datname | count
-------------+-----------+---------+-------
127.0.0.1 | cron_role | ts | 508
127.0.0.1 | tsagent | ts | 60
127.0.0.1 | postgres | ts | 1
127.0.0.1 | pupkin | ts | 1

37. Долгие запросы
$ select * from pg_stat_activity;
...
backend_start | 2015-10-14 15:18:03.01039+00
xact_start | 2015-10-14 15:21:15.336325+00
query_start | 2015-10-14 15:21:30.336325+00
state_change | 2015-10-14 15:21:30.33635+00
...

38. Долгие запросы
$ select * from pg_stat_activity;
...
backend_start | 2015-10-14 15:18:03.01039+00
xact_start | 2015-10-14 15:21:15.336325+00
query_start | 2015-10-14 15:21:30.336325+00
state_change | 2015-10-14 15:21:30.33635+00
...
$ select
client_addr, usename, datname,
clock_timestamp() - xact_start as xact_age,
clock_timestamp() - query_start as query_age,
query
from pg_stat_activity order by xact_start, query_start;

39. Долгие запросы
$ select * from pg_stat_activity;
...
backend_start | 2015-10-14 15:18:03.01039+00
xact_start | 2015-10-14 15:21:15.336325+00
query_start | 2015-10-14 15:21:30.336325+00
state_change | 2015-10-14 15:21:30.33635+00
...
$ select
client_addr, usename, datname,
clock_timestamp() - xact_start as xact_age,
clock_timestamp() - query_start as query_age,
query
from pg_stat_activity order by xact_start, query_start;
clock_timestamp() для вычисления времени работы.
Запросы запоминаем, отстреливаем, оптимизируем (EXPLAIN).

40. Плохие транзакции
$ select * from pg_stat_activity where state in
('idle in transaction', 'idle in transaction (aborted)';
...
xact_start | 2015-10-14 15:21:21.128192+00
query_start | 2015-10-14 15:21:30.336325+00
state_change | 2015-10-14 15:21:30.33635+00
state | idle in transaction
...

41. Плохие транзакции
$ select * from pg_stat_activity where state in
('idle in transaction', 'idle in transaction (aborted)';
...
xact_start | 2015-10-14 15:21:21.128192+00
query_start | 2015-10-14 15:21:30.336325+00
state_change | 2015-10-14 15:21:30.33635+00
state | idle in transaction
...
idle in transaction, idle in transaction (aborted) = плохо
Повод для беспокойств: > 5
clock_timestamp() для вычисления времени работы.
Транзакции отстреливаем, приложение оптимизируем.

42. Блокировки
$ select * from pg_stat_activity where waiting;
...
xact_start | 2015-10-14 15:21:21.128192+00
query_start | 2015-10-14 15:21:30.336325+00
state_change | 2015-10-14 15:21:30.33635+00
waiting | t
...

43. Блокировки
$ select * from pg_stat_activity where waiting;
...
xact_start | 2015-10-14 15:21:21.128192+00
query_start | 2015-10-14 15:21:30.336325+00
state_change | 2015-10-14 15:21:30.33635+00
waiting | t
...
waiting = true = плохо.
clock_timestamp() для вычисления времени работы.
pg_locks для поиска источника блокировки.
Транзакции отстреливаем, приложение оптимизируем.

44. Блокировки
https://github.com/lesovsky/uber-scripts/blob/master/postgresql/sql/c4_06_sho
w_locked_queries.sql
http://big-elephants.com/2013-09/exploring-query-locks-in-postgres/
locked_item | products
waiting | t
waiting_query | update products set avail = false where id = 154;
waiting_mode | RowExclusiveLock
waiting_xact_age | 00:00:07.103685
waiting_query_age | 00:00:01.813508
waiting_pid | 5895
waiting_user | app_role
waiting_state | active
waiting | f
locking_query | alter table products drop column avail;
locking_mode | AccessExclusiveLock
locking_xact_age | 00:00:16.416441
locking_query_age | 00:00:14.416441
locking_pid | 5844
locking_user | postgres
locking_state | idle in transaction

45. pg_stat_statements
$ select * from pg_stat_statements
where blk_read_time <> 0 order by blk_read_time desc;
-[ RECORD 1 ]-------+---------------------------------------
userid | 25078444
dbid | 16411
query | SELECT "id" FROM run_plan_xact(?)
calls | 11165832
total_time | 11743325.6880088
rows | 11165832
shared_blks_hit | 351353214
shared_blks_read | 205557
shared_blks_dirtied | 256053
shared_blks_written | 0
local_blks_hit | 0
local_blks_read | 68894
local_blks_dirtied | 68894
local_blks_written | 0
temp_blks_read | 0
temp_blks_written | 0
blk_read_time | 495425.535999976
blk_write_time | 0

46. pg_stat_statements
$ select * from pg_stat_statements;
...
query | SELECT "id" FROM run_plan_xact(?)
calls | 11165832
total_time | 11743325.6880088
rows | 11165832
blk_read_time | 495425.535999976
blk_write_time | 0
Cреднее время запроса в милисекундах
$ select (sum(total_time) / sum(calls))::numeric(6,3)
from pg_stat_statements;
Самые активно пишущие (в shared_buffers) запросы
$ select query, shared_blks_dirtied
from pg_stat_statements
where shared_blks_dirtied > 0 order by 2 desc;

47. Отчеты
query total time: 15:43:07 (14.9%, CPU: 18.2%, IO: 9.0%)
сalls: 476 (0.00%) rows: 476,000
avg_time: 118881.54ms (IO: 21.2%)
user: app_user db: ustats
query: select
filepath, type, deviceuid
from imv5event
where
state = ?::eventstate
and servertime between $1 and $2
order by servertime desc LIMIT $3 OFFSET $4
https://github.com/PostgreSQL-Consulting/pg-utils/blob/master/sql/glob
al_reports/query_stat_total.sql

48. Отчеты
query total time: 15:43:07 (14.9%, CPU: 18.2%, IO: 9.0%)
сalls: 476 (0.00%) rows: 476,000
avg_time: 118881.54ms (IO: 21.2%)
user: app_user db: ustats
query: select
filepath, type, deviceuid
from imv5event
where
state = ?::eventstate
and servertime between $1 and $2
order by servertime desc LIMIT $3 OFFSET $4
Используем sum() для подсчет общей статистики.
Вычисляем «вклад» запроса в общую статистику.
Использование ресурсов (CPU, IO).

49. За кадром
pg_statio_all_tables, pg_statio_all_indexes
pg_stat_user_functions
Функции определения размеров - df *size*
pgstattuple (contrib)
●
точное определение bloat для индексов и таблиц
●
чем больше размер таблицы, тем больше времени уйдет на
оценку
pg_buffercache (contrib)
●
инспекция shared buffers
●
большие накладые расходы (buffers lock)

50. За кадром
pgfincore
●
низкоуровневые операции с таблицами через mincore().
●
инспекция OS page cache.
pg_stat_kcache
●
использование getrusage() до и после запроса.
●
cpu usage и дисковый ввод-вывод.
●
требует pg_stat_statements и postgresql-9.4.
●
почти не влияет на производительность.

51. Резюме
●
Умение пользоваться статистикой полезно.
●
Статистика в постгресе - это не сложно.
●
Статистика поможет ответить на вопросы.
●
Экспериментируйте.

52. Годные ссылки
Автор, пиши ещё
www.blog.postgresql-consulting.com (eng)
www.thislinux.org (rus)
The Statistics Collector
http://www.postgresql.org/docs/current/static/monitoring-stats.html
System Administration Functions
http://www.postgresql.org/docs/current/static/functions-admin.html
Contrib modules
http://www.postgresql.org/docs/current/static/pgstatstatements.html
http://www.postgresql.org/docs/current/static/pgstattuple.html
http://www.postgresql.org/docs/current/static/pgbuffercache.html
https://github.com/klando/pgfincore
https://github.com/dalibo/pg_stat_kcache
SQL utils and sql code examples
https://github.com/PostgreSQL-Consulting/pg-utils

53. Write Ahead Log
Shared
Buffers
Buffers IO Autovacuum Workers
Autovacuum Launcher
Background Workers
Indexes IO
Query Execution
Query Planning
Client Backends Postmaster
Tables IO
Logger Process Stats Collector
Logical
Replication
WAL Sender
Process
Archiver
Process
Background
Writer
Checkpointer
Process
Network Storage
Recovery Process
WAL Receiver Process
Tables/Indexes Data Files
pg_stat_all_tables
pg_current_xlog_location
pg_replication_slots
pg_stat_replication
pg_stat_archiver
pg_stat_database_conflicts
pg_buffercache
pg_stat_database
pg_stat_activity
pg_stat_user_tables
pg_stat_database
pg_stat_bgwrier
pgstattuplepg_table_size
pg_database_size
pg_index_size
pg_stat_activity
EXPLAIN
pg_stat_statements
pg_locks
pg_stat_user_functions
pg_stat_all_indexes
pg_stat_database
pg_statio_all_indexes
pg_statio_all_tables
pg_xlog_location_diff
nicstat* iostat*
pg_stat_kcache
pg_stat_statements
Спасибо. Вопросы?