PostgreSQL常用運維SQL

一、資料庫連接

1、獲取資料庫實體連接數

select count(*) from pg_stat_activity;

2、獲取資料庫最大連接數

show max_connections

3、查詢當前連接數詳細資訊

select * from pg_stat_activity;

4、查詢資料庫中各個用戶名對應的資料庫連接數

select usename, count(*) from pg_stat_activity group by usename; 

二、賦權操作

1、為指定用戶賦予指定表的select權限

GRANT SELECT ON table_name TO username;

2、修改資料庫表所屬的ownner

alter table table_name owner to username;

3、授予指定用戶指定表的所有權限

grant all privileges on table product to username;

4、授予指定用戶所有表的所有權限

GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO username;

三、資料庫表或者索引

1、獲取資料庫表中的索引

select * from pg_indexes where tablename = 'product'; 

2、獲取當前db中所有表資訊

select * from pg_tables;

3、查詢資料庫安裝了哪些擴展

select * from pg_extension; 

4、查詢資料庫中的所有表及其描述

select relname as TABLE_NAME ,col_description(c.oid, 0) as COMMENTS from pg_class c where relkind = 'r' and relname not like 'pg_%' and relname not like 'sql_%'

四、獲取資料大小

1、查詢執行資料庫大小

select pg_size_pretty (pg_database_size('db_product'));

2、查詢資料庫實體當中各個資料庫大小

select datname, pg_size_pretty (pg_database_size(datname)) AS size from pg_database;

3、查詢單表資料大小

select pg_size_pretty(pg_relation_size('product')) as size;

4、查詢資料庫表包括索引的大小

select pg_size_pretty(pg_total_relation_size('table_name')) as size;

5、查看表中索引大小

select pg_size_pretty(pg_indexes_size('product'));

6、獲取各個表中的資料記錄數

select relname as TABLE_NAME, reltuples as rowCounts from pg_class where relkind = 'r' order by rowCounts desc

7、查看資料庫表對應的資料檔案

select pg_relation_filepath('product');

五、資料庫分析

1、查看資料庫實體的版本

select version();

2、查看最新加載配置的時間

select pg_conf_load_time();

3、查看當前wal的buffer中有多少位元組未寫入磁盤

select pg_xlog_location_diff(pg_current_xlog_insert_location(),pg_current_xlog_location());

4、查詢最耗時的5個sql

select * from pg_stat_statements order by total_time desc limit 5;

備注：需要開啟pg_stat_statements

5、獲取執行時間最慢的3條SQL，并給出CPU占用比例

SELECT substring(query, 1, 1000) AS short_query,
round(total_time::numeric, 2) AS total_time,
calls,
round((100 * total_time / sum(total_time::numeric) OVER ())::numeric, 2) AS percentage_cpu
FROM pg_stat_statements
ORDER BY total_time DESC
LIMIT 3;

6、分析評估SQL執行情況

EXPLAIN ANALYZE SELECT * FROM product

7、查看當前長時間執行卻不結束的SQL

select datname, usename, client_addr, application_name, state, backend_start, xact_start, xact_stay, query_start, query_stay, replace(query, chr(10), ' ') as query from (select pgsa.datname as datname, pgsa.usename as usename, pgsa.client_addr client_addr, pgsa.application_name as application_name, pgsa.state as state, pgsa.backend_start as backend_start, pgsa.xact_start as xact_start, extract(epoch from (now() - pgsa.xact_start)) as xact_stay, pgsa.query_start as query_start, extract(epoch from (now() - pgsa.query_start)) as query_stay , pgsa.query as query from pg_stat_activity as pgsa where pgsa.state != 'idle' and pgsa.state != 'idle in transaction' and pgsa.state != 'idle in transaction (aborted)') idleconnections order by query_stay desc limit 5;

8、查出使用表掃描最多的表

select * from pg_stat_user_tables where n_live_tup > 100000 and seq_scan > 0 order by seq_tup_read desc limit 10;

9、查詢讀取buffer最多的5個SQL

select * from pg_stat_statements order by shared_blks_hit+shared_blks_read desc limit 5;

10、獲取資料庫當前的回滾事務數以及死鎖數

select datname,xact_rollback,deadlocks from pg_stat_database

11、查詢訪問指定表的慢查詢

select * from pg_stat_activity where query ilike '%<table_name>%' and query_start - now() > interval '10 seconds';

六、資料庫備份(非SQL)

1、備份postgres庫并tar打包

pg_dump -h 127.0.0.1 -p 5432 -U postgres -f postgres.sql.tar -Ft

2、備份postgres庫，轉儲資料為帶列名的INSERT命令

pg_dumpall -d postgres -U postgres -f postgres.sql --column-inserts

標籤：PostgreSQL

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