MogDB openGauss常用查詢彙總

奔跑的数据库發表於2024-03-14

MogDB/openGauss 常用查詢彙總

概述

在 MogDB/openGauss 日常運維過程中，會經常透過 SQL 來獲取想要檢視的資訊，這些 SQL 可以作為監控指標、巡檢指標，也可以臨時查詢使用。

透過系統執行緒 id 查對應的 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);"

檢視複製槽

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;

檢視主備延遲

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

--備庫
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 查詢

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;

鎖阻塞詳情

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;

鎖阻塞源統計

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;

資料表大小排序

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;

表膨脹率排序

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 按狀態分類所佔用記憶體大小

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;

檢視 session 中 query 佔用記憶體大小

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;

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