Greenplum各种Tips(不定时更新)

Greenplum接触也有一段时间了,在使用过程中积累了一些命令,在此分享给大家。

1. 查看segment是否有切换(没有记录则没有切换)

SELECT * from gp_segment_configuration where status='d' or mode <> 's';

2.  查看表的分布是否均匀

select gp_segment_id,count(*) from table_name  group by 1;

3. 统计各个数据库大小

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

4.  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 ;

5.  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;

6. 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;

7.  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%';

8. 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';

9. 查看分区表的信息

SELECT tablename,partitiontablename,partitiontype,partitionboundary from pg_partitions where tablename='table_name' order by partitionboundary desc limit 3;

10.  字符串类型转换到整型

ALTER TABLE table_name  ALTER COLUMN COLUMN_NAME  TYPE bigint USING (COLUMN_NAME::bigint);

11.  inet类型转换到varchar类型不要子网掩码

ALTER TABLE table_name ALTER COLUMN COLUMN_NAME TYPE varchar(16) USING host(COLUMN_NAME);

12. 导出数据

COPY t1 to '/home/gpadmin/t1.txt' with delimiter '|';

13. 导入数据

copy t1 from '/home/gpadmin/t1.txt' with delimiter '|' LOG ERRORS INTO INSERT_ERRS SEGMENT REJECT LIMIT 100;

14. 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

15. 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'

16. 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%';

总结:

无非就是一些SQL命令以及数据字典的使用。熟悉数据字典非常重要。

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