MogDB/openGauss常用查询汇总

概述

在MogDB/openGauss日常运维过程中，会经常通过SQL来获取想要查看的信息，这些SQL可以作为监控指标、巡检指标，也可以临时查询使用。

通过系统线程id查对应的query

#!/bin/bash

source ~/.bashrc

thread_sets=`ps -ef |grep -i gaussdb |grep -v grep|awk -F ' ' '{print $2}'|xargs top -n 1 -bHp |grep -i ' worker'|awk -F ' ' '{print $1}'|tr "\n" ","|sed -e 's/,$/\n/'`

gsql -p 26000 postgres -c "select  pid,lwtid,state,query from pg_stat_activity a,dbe_perf.thread_wait_status s where a.pid=s.tid and lwtid in($thread_sets);"

查看hang住SQL的堆栈信息

--查sql对应的线程id（lwtid）
select pid,lwtid,state,query from pg_stat_activity a,dbe_perf.thread_wait_status s where a.pid=s.tid and query like '%xxx%';

--查线程的堆栈信息
pstack lwtid

查看当前数据库下所有表的注释信息

\dt+

或

select current_database(),nspname as schema ,relname,description
from pg_class c ,pg_namespace n,pg_description d
where c.relnamespace=n.oid 
and c.oid=d.objoid 
and d.objsubid=0 
and nspname not in('pg_catalog','db4ai');

查看当前数据库下所有表字段的注释信息

\d+

或

select current_database(),nspname as schema ,relname,attname as column ,atttypid::regtype as datatype,objsubid,atthasdef as default,description
from pg_class c ,pg_namespace n,pg_attribute a,pg_description d
where c.relnamespace=n.oid 
and a.attrelid=c.oid 
and c.oid=d.objoid 
and a.attnum>0 
and d.objsubid=0 
and nspname not in('pg_catalog','db4ai');

查看复制槽

select slot_name,coalesce(plugin,'_') as plugin,slot_type,datoid,coalesce(database,'_') as database,
       (case active when 't' then 1 else 0 end)as active,coalesce(xmin,'_') as xmin,dummy_standby,
       pg_xlog_location_diff(CASE WHEN pg_is_in_recovery() THEN restart_lsn ELSE pg_current_xlog_location() END , restart_lsn)  AS delay_lsn
from pg_replication_slots;

查看主备延迟

--主库
select client_addr,sync_state,pg_xlog_location_diff(pg_current_xlog_location(),receiver_replay_location) from pg_stat_replication;

--备库
select now() AS now, 
       coalesce(pg_last_xact_replay_timestamp(), now()) replay,
       extract(EPOCH FROM (now() - coalesce(pg_last_xact_replay_timestamp(), now()))) AS diff;

慢SQL查询

select datname,usename,client_addr,pid,query_start::text,extract(epoch from (now() - query_start)) as query_runtime,xact_start::text,extract(epoch from(now() - xact_start)) as xact_runtime,state,query 
from pg_stat_activity 
where state not in('idle') and query_start is not null;

锁阻塞详情

with tl as (select usename,granted,locktag,query_start,query 
            from pg_locks l,pg_stat_activity a 
            where l.pid=a.pid and locktag in(select locktag from pg_locks where granted='f')) 
select ts.usename locker_user,ts.query_start locker_query_start,ts.granted locker_granted,ts.query locker_query,tt.query locked_query,tt.query_start locked_query_start,tt.granted locked_granted,tt.usename locked_user,extract(epoch from now() - tt.query_start) as locked_times
from (select * from tl where granted='t') as ts,(select * from tl where granted='f') tt 
where ts.locktag=tt.locktag 
order by 1;

锁阻塞源统计

with tl as (select usename,granted,locktag,query_start,query 
            from pg_locks l,pg_stat_activity a 
            where l.pid=a.pid and locktag in(select locktag from pg_locks where granted='f')) 
select usename,query_start,granted,query,count(query) count 
from tl 
where granted='t' 
group by usename,query_start,granted,query 
order by 5 desc;

数据表大小排序

SELECT CURRENT_CATALOG AS datname,nsp.nspname,rel.relname,
             pg_total_relation_size(rel.oid)       AS bytes,
             pg_relation_size(rel.oid)             AS relsize,
             pg_indexes_size(rel.oid)              AS indexsize,
             pg_total_relation_size(reltoastrelid) AS toastsize
FROM pg_namespace nsp JOIN pg_class rel ON nsp.oid = rel.relnamespace
WHERE nspname NOT IN ('pg_catalog', 'information_schema','snapshot') AND rel.relkind = 'r'
order by 4 desc limit 100; 

索引大小排序

select CURRENT_CATALOG AS datname,schemaname schema_name,relname table_name,indexrelname index_name,pg_table_size(indexrelid) as index_size 
from pg_stat_user_indexes 
where schemaname not in('pg_catalog', 'information_schema','snapshot')
order by 4 desc limit 100;

表膨胀率排序

select CURRENT_CATALOG AS datname,schemaname,relname,n_live_tup,n_dead_tup,round((n_dead_tup::numeric/(case (n_dead_tup+n_live_tup) when 0 then 1 else (n_dead_tup+n_live_tup) end ) *100),2) as dead_rate
from pg_stat_user_tables
where (n_live_tup + n_dead_tup) > 10000
order by 5 desc limit 100;

session按状态分类所占用内存大小

select state,sum(totalsize)::bigint as totalsize
from gs_session_memory_detail m,pg_stat_activity a 
where substring_inner(sessid,position('.' in sessid) +1)=a.sessionid and usename<>'mondb' and pid != pg_backend_pid() 
group by state order by sum(totalsize) desc;

查看session中query占用内存大小

select sessionid, coalesce(application_name,'')as application_name,
       coalesce(client_addr::text,'') as client_addr,sum(usedsize)::bigint as usedsize, 
       sum(totalsize)::bigint as totalsize,query 
from gs_session_memory_detail s,pg_stat_activity a 
where substring_inner(sessid,position('.' in sessid) +1)=a.sessionid 
group by sessionid,query,application_name,client_addr 
order by sum(totalsize) desc limit 10;

查看指定schema下除主键以外的非空约束

select table_schema||'.'||table_name||'.'||column_name as tna 
from information_schema.columns 
where is_nullable='NO' and table_schema in('su1') 
and tna not in(select table_schema||'.'||relname||'.'||column_name as tn 
               from pg_constraint con,pg_class c,pg_attribute a,information_schema.columns col 
               where con.conrelid=c.oid and a.attrelid=c.oid and contype='p' and a.attnum=con.conkey[1] and col.table_name=c.relname and a.attname=col.column_name);

查询一段时间内产生的wal数据量

select pg_size_pretty(sum(size)) as " WAL size"
from pg_ls_waldir() 
where modification > (now() - interval '60 minutes') ;