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  • postgresql数据库常用命令

    --获取数据库软件版本
    select version();
    --获取数据库启动时间
    select pg_postmaster_start_time();
    --获取配置文件最近load时间
    select pg_conf_load_time();
    --获取当前数据库时区
    show timezone;
    --获取当前实例中所有数据库
    psql -l
    --获取当前数据库用户
    select user;
    select current_user;
    --获取当前会话用户
    select session_user;
    --获取会话客户端地址及端口
    select inet_client_addr(),inet_client_port();
    --获取当前数据库服务器地址及端口
    select inet_server_addr(),inet_server_port();
    --获取当前会话服务进程
    select pg_backend_pid();
    --获取当前参数配置
    show shared_buffer;
    select current_setting('shared_buffers');
    --修改会话参数配置
    set maintenance_work_mem to '32m';
    select set_confit('maintenance_work_mem','32m',false);
    --获取当前WAL文件
    select pg_xlogfile_name(pg_current_xlog_location());
    --获取没写到磁盘的WAL buffer
    select pg_xlog_location_diff(pg_current_xlog_insert_location(),pg_current_xlog_location());
    --获取实例中当前进行的备份
    select pg_is_in_backup(),pg_backup_start_time();
    --获取当前实例的角色状态(primary or standby)
    select pg_is_in_recovery();
    --获取数据库大小
    select pg_database_size('mydb'),pg_size_pretty(pg_database_size('mydb'));
    --获取表大小
    --表
    select pg_size_pretty(pg_relation_size('mytab'));
    --表及索引
    select pg_size_pretty(pg_total_relation_size('mytab'));
    --获取索引大小
    select pg_size_pretty(pg_indexes_size('mytab'));
    --获取表空间大小

    select pg_size_pretty(pg_tablespace_size('my_tbs'));

    --获取表中每个数据块的自由空间

    select pg_freespace('mytab');

    --获取表中每个数据块中自由空间比例

    SELECT (100 * (upper - lower) / pagesize::float8)::integer AS free_pct
    FROM page_header(get_raw_page('mytab',11));

    --获取表对应的数据文件
    select pg_relation_filepath('mytab');
    --重新加载配置文件
    pg_ctl reload
    select pg_reload_conf();
    --切换log文件
    select pg_rotate_logfile();
    --切换xlog文件
    select pg_rotate_xlog();
    --手工产生检查点
    checkpoint;
    --取消正在执行的SQL
    select pg_cancel_backend(pid);
    --终止后台服务进程
    select pg_terminate_backend(pid);
    --获取正在执行的SQL

    select pid,username,query_start,query from pg_stat_activity;

    --获取Combo Command Ids

    SELECT t_xmin AS xmin,
    t_xmax::text::int8 AS xmax,
    t_field3::text::int8 AS cmin_cmax,
    (t_infomask::integer & X'0020'::integer)::bool AS is_combocid
    FROM heap_page_items(get_raw_page('mytab',0))
    ORDER BY 2 DESC, 3;

    --创建获取某数据块元组原型视图

    CREATE VIEW t1_page0 AS
    SELECT '(0,'|| lp || ')' AS ctid,
    CASE lp_flags
    WHEN 0 THEN 'Unused'
    WHEN 1 THEN 'Normal'
    WHEN 2 THEN 'Redirect to '|| lp_off
    WHEN 3 THEN 'Dead'
    END,
    t_xmin::text::int8 AS xmin,
    t_xmax::text::int8 AS xmax,
    t_ctid
    FROM heap_page_items(get_raw_page('t1',0))
    ORDER BY lp;

    select * from t1_page0;

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  • 原文地址:https://www.cnblogs.com/lhdz_bj/p/9019114.html
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