citus中DDL操作规范有哪些

本篇内容主要讲解"citus中DDL操作规范有哪些"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"citus中DDL操作规范有哪些"吧!

背景

citus是PG的一个插件，插件主要针对普通SQL（非UTILITY）加HOOK进行了一些ROUTE处理，同时使用UDF对表进行新建分区的操作。

如果用户如果要执行DDL，那么CITUS无法接管，应该如何操作呢？

分两种情况，一种需要在所有节点（CN以及WORKER）执行，还有一些只需要在CN节点执行。

需要在所有节点（CN以及WORKER）执行的DDL

由于这些DDL在CN节点执行时，不会自动在WORKER执行，所以需要在所有节点执行。

常用的DDL包括：

1、新建用户

Command:     CREATE ROLE  Description: define a new database role  Syntax:  CREATE ROLE name [ [ WITH ] option [ ... ] ]    where option can be:          SUPERUSER | NOSUPERUSER      | CREATEDB | NOCREATEDB      | CREATEROLE | NOCREATEROLE      | INHERIT | NOINHERIT      | LOGIN | NOLOGIN      | REPLICATION | NOREPLICATION      | BYPASSRLS | NOBYPASSRLS      | CONNECTION LIMIT connlimit      | [ ENCRYPTED ] PASSWORD 'password'      | VALID UNTIL 'timestamp'      | IN ROLE role_name [, ...]      | IN GROUP role_name [, ...]      | ROLE role_name [, ...]      | ADMIN role_name [, ...]      | USER role_name [, ...]      | SYSID uid

2、新建数据库

Command:     CREATE DATABASE  Description: create a new database  Syntax:  CREATE DATABASE name      [ [ WITH ] [ OWNER [=] user_name ]             [ TEMPLATE [=] template ]             [ ENCODING [=] encoding ]             [ LC_COLLATE [=] lc_collate ]             [ LC_CTYPE [=] lc_ctype ]             [ TABLESPACE [=] tablespace_name ]             [ ALLOW_CONNECTIONS [=] allowconn ]             [ CONNECTION LIMIT [=] connlimit ]             [ IS_TEMPLATE [=] istemplate ] ]

所有节点新建数据库后一定不要忘记：

2.1、在所有节点新增的DB内添加citus插件

create extension citus;

2.2、仅在CN节点，连到新建数据库里面添加worker节点。（千万不要忘记，每新建一个DB，都需要重复做。所以可以把它做到模板库里面，新建DB时，使用模板新建。）

例如

su - postgres -c "psql -c \"SELECT * from master_add_node('xxx.xxx.xxx.224', 1921);\""    su - postgres -c "psql -c \"SELECT * from master_add_node('xxx.xxx.xxx.230', 1921);\""    su - postgres -c "psql -c \"SELECT * from master_add_node('xxx.xxx.xxx.231', 1921);\""    su - postgres -c "psql -c \"SELECT * from master_add_node('xxx.xxx.xxx.225', 1921);\""    su - postgres -c "psql -c \"SELECT * from master_add_node('xxx.xxx.xxx.227', 1921);\""    su - postgres -c "psql -c \"SELECT * from master_add_node('xxx.xxx.xxx.232', 1921);\""    su - postgres -c "psql -c \"SELECT * from master_add_node('xxx.xxx.xxx.226', 1921);\""    su - postgres -c "psql -c \"SELECT * from master_add_node('xxx.xxx.xxx.229', 1921);\""        postgres=# SELECT * FROM master_get_active_worker_nodes();       node_name    | node_port     ----------------+-----------     xxx.xxx.xxx.227 |      1921     xxx.xxx.xxx.229 |      1921     xxx.xxx.xxx.231 |      1921     xxx.xxx.xxx.225 |      1921     xxx.xxx.xxx.224 |      1921     xxx.xxx.xxx.226 |      1921     xxx.xxx.xxx.230 |      1921     xxx.xxx.xxx.232 |      1921    (8 rows)

2.3、如果使用了MX功能，还需要添加一遍。

参考

《PostgreSQL sharding : citus 系列1 - 多机部署（含OLTP(TPC-B)测试）》

### CN MX : OLTP 读、写能力扩展

3、新建schema

Command:     CREATE SCHEMA  Description: define a new schema  Syntax:  CREATE SCHEMA schema_name [ AUTHORIZATION role_specification ] [ schema_element [ ... ] ]  CREATE SCHEMA AUTHORIZATION role_specification [ schema_element [ ... ] ]  CREATE SCHEMA IF NOT EXISTS schema_name [ AUTHORIZATION role_specification ]  CREATE SCHEMA IF NOT EXISTS AUTHORIZATION role_specification    where role_specification can be:        user_name    | CURRENT_USER    | SESSION_USER

4、新建函数

自定义函数    Command:     CREATE FUNCTION  Description: define a new function  Syntax:  CREATE [ OR REPLACE ] FUNCTION      name ( [ [ argmode ] [ argname ] argtype [ { DEFAULT | = } default_expr ] [, ...] ] )      [ RETURNS rettype        | RETURNS TABLE ( column_name column_type [, ...] ) ]    { LANGUAGE lang_name      | TRANSFORM { FOR TYPE type_name } [, ... ]      | WINDOW      | IMMUTABLE | STABLE | VOLATILE | [ NOT ] LEAKPROOF      | CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT      | [ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER      | PARALLEL { UNSAFE | RESTRICTED | SAFE }      | COST execution_cost      | ROWS result_rows      | SET configuration_parameter { TO value | = value | FROM CURRENT }      | AS 'definition'      | AS 'obj_file', 'link_symbol'    } ...      [ WITH ( attribute [, ...] ) ]

5、新建操作符

自定义操作符

6、新建类型

自定义类型

7、新建插件

Command:     CREATE EXTENSION  Description: install an extension  Syntax:  CREATE EXTENSION [ IF NOT EXISTS ] extension_name      [ WITH ] [ SCHEMA schema_name ]               [ VERSION version ]               [ FROM old_version ]               [ CASCADE ]

以上为常用的DDL，需要在所有节点执行。

仅需要在CN节点执行的DDL

1、新建表，调用citus函数创建分片。

例子

create table test(id int primary key, info text);    select create_distributed_table('test','id');

2、新建视图

Command:     CREATE VIEW  Description: define a new view  Syntax:  CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] [ RECURSIVE ] VIEW name [ ( column_name [, ...] ) ]      [ WITH ( view_option_name [= view_option_value] [, ... ] ) ]      AS query      [ WITH [ CASCADED | LOCAL ] CHECK OPTION ]

视图仅需在CN节点操作，因为SQL最后会解析成视图里面的内容。例如

create view v2 as select * from pgbench_accounts where aid=1;    create view v3 as select * from v2;    postgres=# explain verbose select * from v2;                                                                     QUERY PLAN                                                                      -------------------------------------------------------------------------------------------------------------------------------------------------   Custom Scan (Citus Router)  (cost=0.00..0.00 rows=0 width=0)     Output: remote_scan.aid, remote_scan.bid, remote_scan.abalance, remote_scan.filler     Task Count: 1     Tasks Shown: All     ->  Task           Node: host=172.24.211.232 port=1921 dbname=postgres           ->  Index Scan using pgbench_accounts_pkey_106819 on public.pgbench_accounts_106819 pgbench_accounts  (cost=0.28..2.50 rows=1 width=97)                 Output: pgbench_accounts.aid, pgbench_accounts.bid, pgbench_accounts.abalance, pgbench_accounts.filler                 Index Cond: (pgbench_accounts.aid = 1)  (9 rows)    postgres=# explain verbose select * from v3;                                                                     QUERY PLAN                                                                      -------------------------------------------------------------------------------------------------------------------------------------------------   Custom Scan (Citus Router)  (cost=0.00..0.00 rows=0 width=0)     Output: remote_scan.aid, remote_scan.bid, remote_scan.abalance, remote_scan.filler     Task Count: 1     Tasks Shown: All     ->  Task           Node: host=172.24.211.232 port=1921 dbname=postgres           ->  Index Scan using pgbench_accounts_pkey_106819 on public.pgbench_accounts_106819 pgbench_accounts  (cost=0.28..2.50 rows=1 width=97)                 Output: pgbench_accounts.aid, pgbench_accounts.bid, pgbench_accounts.abalance, pgbench_accounts.filler                 Index Cond: (pgbench_accounts.aid = 1)  (9 rows)

到此，相信大家对"citus中DDL操作规范有哪些"有了更深的了解，不妨来实际操作一番吧！这里是网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！