SQL Queries for Checking PostgreSQL Operating Status

postgres=# select version();
                                                 version
----------------------------------------------------------------------------------------------------------
 PostgreSQL 10.11 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39), 64-bit
(1 row)

SELECT datname, xact_commit, xact_rollback FROM pg_stat_database;

SELECT datname, round(blks_hit*100/(blks_hit+blks_read), 2) AS cache_hit_ratio
FROM pg_stat_database WHERE blks_read > 0;

SELECT relname, round(heap_blks_hit*100/(heap_blks_hit+heap_blks_read), 2)
AS cache_hit_ratio FROM pg_statio_user_tables
WHERE heap_blks_read > 0 ORDER BY cache_hit_ratio;

SELECT relname, indexrelname, round(idx_blks_hit*100/(idx_blks_hit+idx_blks_read), 2)
AS cache_hit_ratio FROM pg_statio_user_indexes
WHERE idx_blks_read > 0 ORDER BY cache_hit_ratio;

SELECT relname, seq_scan, seq_tup_read, seq_tup_read/seq_scan AS tup_per_read FROM pg_stat_user_tables
WHERE seq_scan > 0 ORDER BY tup_per_read DESC;

SELECT relname, n_tup_upd, n_tup_hot_upd, round(n_tup_hot_upd*100/n_tup_upd, 2) AS hot_upd_ratio
FROM pg_stat_user_tables WHERE n_tup_upd > 0 ORDER BY hot_upd_ratio;

SELECT pid, datname, usename, state, backend_type FROM pg_stat_activity;

SELECT pid, query_start, substr(query, 0, 50) FROM pg_stat_activity WHERE state='active' ORDER BY query_start;

select * from pg_stat_archiver;

SELECT datname,deadlocks FROM pg_stat_database where datname = 'pgbench';

SELECT l.pid, l.granted, d.datname, l.locktype, relation, relation::regclass, transactionid, l.mode
FROM pg_locks l LEFT JOIN pg_database d ON  l.database = d.oid
WHERE l.pid != pg_backend_pid()
ORDER BY l.pid ;

SELECT pid, state, wait_event, wait_event_type, (NOW() - xact_start)::INTERVAL(3) AS tx_duration, (NOW() - query_start)::INTERVAL(3) AS sql_duration, query
FROM pg_stat_activity
WHERE pid <> pg_backend_pid() ;

SELECT
    checkpoints_timed,
    checkpoints_req,
    checkpoint_write_time,
    checkpoint_sync_time,
    buffers_checkpoint
FROM
    pg_stat_bgwriter;

SELECT relname,n_live_tup,n_dead_tup,last_autovacuum,autovacuum_count
FROM pg_stat_user_tables;

SELECT relname,last_analyze,last_autoanalyze,analyze_count,autoanalyze_count
FROM pg_stat_user_tables;

select datname,temp_files,temp_bytes from pg_stat_database;

SELECT datname, SUBSTRING(query, 1, 40) AS query, calls, TRUNC( total_time::NUMERIC, 3 ) AS total_time
FROM pg_stat_statements LEFT OUTER JOIN pg_database ON  pg_stat_statements.dbid = pg_database.oid
WHERE datname = 'pgbench'
ORDER BY total_time DESC
LIMIT 5 ;

select pg_size_pretty(pg_database_size('pgbench'));

select pg_relation_size('pgbench');

select pg_total_relation_size('pgbench');

SELECT pgn.nspname, relname, pg_size_pretty(relpages::bigint * 8 * 1024) AS size, CASE WHEN relkind =
't' THEN (SELECT pgd.relname FROM pg_class pgd WHERE pgd.reltoastrelid = pg.oid) WHEN nspname =
'pg_toast' AND relkind = 'i' THEN (SELECT pgt.relname FROM pg_class pgt WHERE SUBSTRING(pgt.relname
FROM 10) = REPLACE(SUBSTRING(pg.relname FROM 10), '_index', '')) ELSE (SELECT pgc.relname FROM
pg_class pgc WHERE pg.reltoastrelid = pgc.oid) END::varchar AS refrelname, CASE WHEN nspname =
'pg_toast' AND relkind = 'i' THEN (SELECT pgts.relname FROM pg_class pgts WHERE pgts.reltoastrelid =
(SELECT pgt.oid FROM pg_class pgt WHERE SUBSTRING(pgt.relname FROM 10) = REPLACE(SUBSTRING(pg.relname
FROM 10), '_index', ''))) END AS relidxrefrelname, relfilenode, relkind, reltuples::bigint, relpages
FROM pg_class pg, pg_namespace pgn WHERE pg.relnamespace = pgn.oid AND pgn.nspname NOT IN
('information_schema', 'pg_catalog') ORDER BY relpages DESC;

select tablename, attname, avg_width from pg_stats;

SELECT * FROM pg_stats WHERE tablename = 'xxxxxxx';

select relname, n_tup_ins as insert_cnt, n_tup_upd as update_cnt, n_tup_del as delete_cnt from pg_stat_user_tables;

select datname, temp_files, pg_size_pretty(temp_bytes) as temp_bytes, pg_size_pretty(round(temp_bytes/temp_files,2)) as temp_file_size
from pg_stat_database
where temp_files > 0;

select relname, seq_scan, seq_tup_read,seq_tup_read/seq_scan as tup_per_read
from pg_stat_user_tables
where seq_scan > 0 order by tup_per_read desc;

select relname, n_live_tup, n_dead_tup,round(n_dead_tup*100/(n_dead_tup+n_live_tup), 2)  as dead_ratio,pg_size_pretty(pg_relation_size(relid))
from pg_stat_user_tables
where n_live_tup > 0
order by dead_ratio desc;

select * from pg_statio_all_tables;

select substr(query, 0, 160) as query, calls
  ,(total_time / 1000)::numeric(10,3) as total_time_sec
  ,(mean_time / 1000)::numeric(10,3) as avg_time_sec
  ,(min_time / 1000)::numeric(10,3) as min_time_sec
 ,(max_time / 1000)::numeric(10,3) as max_time_sec
from pg_stat_statements
order by total_time desc
limit 10;

select v.pid, v.datname, c.relname, v.phase, v.heap_blks_total, v.heap_blks_scanned, v.heap_blks_vacuumed, v.index_vacuum_count, v.max_dead_tuples, v.num_dead_tuples
from pg_stat_progress_vacuum as v join pg_class as c on  v.relid = c.relfilenode ;

select relid,relname from pg_stat_all_tables;

select
    relname,
    coalesce(seq_tup_read,0)+coalesce(idx_tup_fetch,0)+
    coalesce(n_tup_ins,0)+coalesce(n_tup_upd,0)+coalesce(n_tup_del,0) as total,
    coalesce(seq_tup_read,0)+coalesce(idx_tup_fetch,0) as select,
    coalesce(n_tup_ins,0) as insert,
    coalesce(n_tup_upd,0) as update,
    coalesce(n_tup_del,0) as delete
from pg_stat_user_tables
order by total desc;

select *,(heap_blks_hit*100) / (heap_blks_read+heap_blks_hit) as ritu
from pg_statio_all_tables
where heap_blks_hit >= 1
order by ritu;

select * from pg_stat_all_indexes;

SELECT name,setting,unit,context FROM pg_settings;

internal：not modifiable (for checking build-time settings)
postmaster：at server startup
sighup：upon configuration file reload
backend：determined at session establishment
superuser：dynamically modifiable with superuser privileges
user：dynamically modifiable by regular users