作者：lianghc
在greenplum 使用过程中积累的一些常用查询语句，整理出来备忘。欢迎各位留言补充。都是SQL命令以及数据字典的使用。熟悉数据字典非常重要。三个重要的schema:pg_catalog,pg_toolkit,information_schema,其中information_schema 中的数据字典都在视图中，并且这个schema中提供了大量的操作数据字典的函数值得研究。
一 数据库运行状态查询管理
1. greenplum查询正在运行的sql，session
-- 方法1：
SELECT
tt.procpid, -- pid
usename user_name, -- 执行的用户
backend_start, -- 会话开始时间
query_start, -- 查询开始时间
waiting, -- 是否等待执行
now() - query_start AS current_query_time, -- 累计执行时间
now() - backend_start AS current_session_time,*/
current_query,
client_addr , datname
FROM
pg_stat_activity tt
WHERE current_query != '<IDLE>'
ORDER BY current_query_time DESC;
-- 方法2（通过视图查）
SELECT
procpid,
START,
now() - START AS lap,
current_query,
-- count() over() count_num,
t2.rolname,t3.rsqname,
ip
FROM
(
SELECT
backendid,
pg_stat_get_backend_userid(S.backendid) as uid,
pg_stat_get_backend_client_addr(S.backendid) as ip,
pg_stat_get_backend_pid (S.backendid) AS procpid,
pg_stat_get_backend_activity_start (S.backendid) AS START,
pg_stat_get_backend_activity (S.backendid) AS current_query
FROM
(
SELECT
pg_stat_get_backend_idset () AS backendid
) AS S
) AS t1 left join pg_authid t2 on t1.uid=t2.oid
left join pg_resqueue t3 on t2.rolresqueue=t3.oid
WHERE
current_query!= '<IDLE>'
ORDER BY lap DESC;
-- 方法3（限定了角色和资源队列，查当前账号正在查询的语句）
SELECT
rolname,
rsqname,
pid,
GRANTED,
current_query,
datname
FROM
pg_roles t1,
gp_toolkit.gp_resqueue_status t2 ,
pg_locks t3 ,
pg_stat_activity t4
WHERE
t1.rolresqueue = t3.objid
AND t3.objid=t2.queueid
and t4.procpid=t3.pid
2.终止执行的sql
select pg_terminate_backend(48988); --pid
3.查看greemplum资源队列状态
SELECT * FROM gp_toolkit.gp_resqueue_status;
4. 查看greemplum资源队列锁
SELECT * FROM gp_toolkit.gp_locks_on_resqueue WHERE lorwaiting='true';
5.查看greemplum资源队列优先级
select * from gp_toolkit.gp_resq_priority_statement;
6. 查看greemplum所有连接 类似mysql SHOW PROCESSLIST
select * from pg_stat_activity; -- 所有状态的连接
7.greemplum磁盘使用，通过SQL查看Greenplum中用了多少空间
select datname,pg_size_pretty(pg_database_size(datname)) from pg_database;
8.查看greemplum节点状态
select * from gp_segment_configuration tt
select * from gp_segment_configuration tt where tt.status='d'; -- 状态为down
9. 节点故障等历史信息
select * from gp_configuration_history tt order by 1 desc ;
10.数据倾斜
SELECT
t1.gp_segment_id,
t1.count_tatol,
round(t1.count_tatol-(AVG(t1.count_tatol) over()) ,0)
FROM
(
SELECT
gp_segment_id,
COUNT (*) count_tatol
FROM
<tablename> -- 要查的表
GROUP BY
gp_segment_id
) t1
order by 3
11.greemplum表或索引大小 （占用空间）
select pg_size_pretty(pg_relation_size('gp_test'));
12.greemplum表和索引大小（占用空间）
select pg_size_pretty(pg_total_relation_size('gp_test'));
13.greemplum查看指定数据库大小（占用空间）
select pg_size_pretty(pg_database_size('postgres'));
14.greemplum所有数据库大小（占用空间）
select datname,pg_size_pretty(pg_database_size(datname)) from pg_database;
15.查看greemplum数据分布情况
select gp_segment_id,count(*) from gp_test group by gp_segment_id order by 1;
二 查源数据
16.查看greemplum数据表更新时间
SELECT
*
FROM
pg_stat_last_operation,
pg_class
WHERE
objid = oid
AND relname = 'base_common'; -- 表名
17.通过sql 获取greemplum表的预估数据量
select
relname,
reltuples::int as total
from
pg_class
where
relname = 'base_common'
and relnamespace = (select oid from pg_namespace where nspname = 'positions');
18.通过sql 获取greemplum获取分布键
SELECT string_agg(att.attname,',' order by attrnums) as distribution
FROM gp_distribution_policy a,pg_attribute att
WHERE a.localoid ='bi_data.schoolmate_relations'::regclass
and a.localoid = att.attrelid
and att.attnum = any(a.attrnums);
19. 通过sql获取 greemplum指定表结构
SELECT
attname, typname
FROM
pg_attribute
INNER JOIN pg_class ON pg_attribute.attrelid = pg_class.oid
INNER JOIN pg_type ON pg_attribute.atttypid = pg_type.oid
INNER JOIN pg_namespace on pg_class.relnamespace=pg_namespace.oid --
WHERE
pg_attribute.attnum > 0
AND attisdropped <> 't'
AND pg_namespace.nspname='resumes'
AND pg_class.relname= 'base_common'
-- and pg_class.relname ~~* any(array['%some%', '%someelse']));
order by pg_attribute.attnum
同时可以参考：
【greenplum】greenplum 数据字典实践--通过sql脚本查询表结构，拼装建表语句
【greenplum】 获取表结构，实现类似mysql show create table 功能
20.显示哪些没有统计信息且可能需要ANALYZE的表
SELECT * from gp_toolkit.gp_stats_missing ;
21. 显示在系统表中被标记为掉线的Segment的信息
SELECT * from gp_toolkit.gp_pgdatabase_invalid;
22. 显示库中表的大小（单位G）
SELECT sotdoid,sotdsize/1024/1024/1024 as sotdsize,sotdtoastsize,sotdadditionalsize,sotdschemaname,sotdtablename from gp_toolkit.gp_size_of_table_disk order by sotdsize desc;
23. 查询一个库中有多少表（如果有分区表不列出子分区）
SELECT relname from pg_class a,pg_namespace b where relname not like '%prt%' and relkind ='r' and a.relnamespace=b.oid and nspname not in ('pg_catalog','information_schema','gp_toolkit') and nspname not like '%pg_temp%';
24. 查询某个用户对某个表有什么权限
select * from INFORMATION_SCHEMA.role_table_grants where grantee='user_name' and table_name='table';
25. 查看分区表的信息
SELECT tablename,partitiontablename,partitiontype,partitionboundary from pg_partitions where tablename='table_name' order by partitionboundary desc;
26. 导入数据
copy t1 from '/home/gpadmin/t1.txt' with delimiter '|' LOG ERRORS INTO INSERT_ERRS SEGMENT REJECT LIMIT 100;
27. 远程导入数据
psql -h 1.1.1.1 -U user_name -d db_name -W -c "copy tb1 from stdin with delimiter '|'" < /home/gpadmin/tb1.txt
28. 导数据指定分隔符（和mysql的select into outfile很像）
psql -d db_name -c "select * from tb1" -o tb1.txt -t -A -F $'\t'
29. 生成授权语句
SELECT 'grant select on '||relname||' to user_name;' from pg_class a,pg_namespace b where relname not like '%prt%' and relkind ='r' and has_table_privilege('user_name',a.oid,'select')='f' and a.relnamespace=b.oid and nspname not in ('pg_catalog','information_schema','gp_toolkit')
and nspname not like '%pg_temp%';
30 .给用户授权
select 'grant all on SCHEMA ' || tt.autnspname || ' to tuser;' as grant_script from gp_toolkit.__gp_user_tables tt -- group by tt.autnspname
union -- all
select 'grant all on table ' || tt.autnspname || '.' ||tt.autrelname || ' to tuser;' grant_script from gp_toolkit.__gp_user_tables tt;
