合 PG中的分区表

发布日期 2021年7月28日 · 已更新 2024年8月13日

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Tags： PG PostgreSQL 整理自网络分区表继承

👉 本文共约5606个字，系统预计阅读时间或需22分钟。

表分区简介
传统方式实现分区
创建分区表
1 创建主表
2 创建分区表
3 分区键上建索引
4 创建触发器函数
5 创建触发器
查看分区表
1 查看所有表
2 查看主表
3 查看分区表
测试
插入数据
查看主表数据
查看分区表数据
PG 10 新特性
范围分区
示例
列表分区
绑定分区
查询
PG 11新特性
hash分区语法
默认分区
多级分区
ATTACH/DETACH 分区
外部表做为分区表
索引增强
DML改进
UPDATE可以在分区之间移动行
INSERT/COPY可以路由到外部分区
INSERT .. ON CONFLICT DO UPDATE/NOTHING
管理分区
移除数据/分区
增加分区
绑定分区
约束排除
约束排除关闭
约束排除开启
可选的分区方式
PG分区表大小查询
PG12之前
PG12开始
PG 15中的增强特性
总结

表分区简介

http://postgres.cn/docs/13/ddl-partitioning.html

　　在数据库日渐庞大的今天，为了方便对数据库数据的管理，比如按时间，按地区去统计一些数据时，基数过于庞大，多有不便。很多商业数据库都提供分区的概念，按不同的维度去存放数据，便于后期的管理，PostgreSQL也不例外。

　　PostgresSQL分区的意思是把逻辑上的一个大表分割成物理上的几块儿。分区不仅能带来访问速度的提升，关键的是，它能带来管理和维护上的方便。

　　分区的具体好处是：

某些类型的查询性能可以得到极大提升。
更新的性能也可以得到提升，因为表的每块的索引要比在整个数据集上的索引要小。如果索引不能全部放在内存里，那么在索引上的读和写都会产生更多的磁盘访问。
批量删除可以用简单的删除某个分区来实现。
可以将很少用的数据移动到便宜的、转速慢的存储介质上。

　　PostgreSQL 有两种父、子表关系：分区（partition）和继承（inherit）。

　　在PG里，表分区是通过表继承来实现的，一般都是建立一个主表，里面是空，然后每个分区都去继承它。无论何时，都应保证主表里面是空的。 在PG 10之前，只能通过表继承来实现分区，从PG 10开始，可以通过DDL语句来直接创建分区表（内部原理也是通过继承来实现），这被称为声明式分区表（declaratively patitioned table）或内置分区表。PG 10仅支持范围分区和列表分区，尚未支持散列Hash分区，PG 11支持Hash分区。

　　小表分区不实际，表在多大情况下才考虑分区呢？PostgresSQL官方给出的建议是：当表本身大小超过了机器物理内存的实际大小时（the size of the table should exceed the physical memory of the database server），可以考虑分区。

分区表注意事项：
不支持全局的唯一、主键、排除、外键约束，只能在对应的分区建立这些约束。
索引只能在分区中创建，在主表创建不能继承到分区中。
更新数据时不能进行数据跨分区移动，否则会报错。
分区表继承特性的限制：
i.分区除了主表外，不能继承其他父表；
ii.一个普通表不能继承分区表主表。

传统方式实现分区

参考：https://www.dbaup.com/pgzhongdebiaojichengheonlyguanjianci.html

创建分区表

1 创建主表

 create table tbl_partition (
 id integer,
 name varchar(20),
 gender boolean,
 join_date date,
 dept char(4));

create table tbl_partition (

id integer,

name varchar(20),

gender boolean,

join_date date,

dept char(4));

2 创建分区表

create table tbl_partition_202011 (
check ( join_date >= DATE '2020-11-01' AND join_date < DATE '2020-12-01' )       
) INHERITS (tbl_partition);

create table tbl_partition_202012 (
check ( join_date >= DATE '2020-12-01' AND join_date < DATE '2021-01-01' )      
) INHERITS (tbl_partition);

create table tbl_partition_202101 (
check ( join_date >= DATE '2021-01-01' AND join_date < DATE '2021-02-01' )      
) INHERITS (tbl_partition);

create table tbl_partition_202102 (
check ( join_date >= DATE '2021-02-01' AND join_date < DATE '2021-03-01' )  
) INHERITS (tbl_partition);

create table tbl_partition_202103 (
check ( join_date >= DATE '2021-03-01' AND join_date < DATE '2021-04-01' ) 
) INHERITS (tbl_partition);

create table tbl_partition_202104 (
check ( join_date >= DATE '2021-04-01' AND join_date < DATE '2021-05-01' )  
) INHERITS (tbl_partition);

create table tbl_partition_202105 (
check ( join_date >= DATE '2021-05-01' AND join_date < DATE '2021-06-01' )  
) INHERITS (tbl_partition);

create table tbl_partition_202011 (

check ( join_date >= DATE '2020-11-01' AND join_date < DATE '2020-12-01' )

) INHERITS (tbl_partition);

create table tbl_partition_202012 (

check ( join_date >= DATE '2020-12-01' AND join_date < DATE '2021-01-01' )

) INHERITS (tbl_partition);

create table tbl_partition_202101 (

check ( join_date >= DATE '2021-01-01' AND join_date < DATE '2021-02-01' )

) INHERITS (tbl_partition);

create table tbl_partition_202102 (

check ( join_date >= DATE '2021-02-01' AND join_date < DATE '2021-03-01' )

) INHERITS (tbl_partition);

create table tbl_partition_202103 (

check ( join_date >= DATE '2021-03-01' AND join_date < DATE '2021-04-01' )

) INHERITS (tbl_partition);

create table tbl_partition_202104 (

check ( join_date >= DATE '2021-04-01' AND join_date < DATE '2021-05-01' )

) INHERITS (tbl_partition);

create table tbl_partition_202105 (

check ( join_date >= DATE '2021-05-01' AND join_date < DATE '2021-06-01' )

) INHERITS (tbl_partition);

查看分区：

postgres=## \d
                List of relations
 Schema |         Name         | Type  |  Owner
--------+----------------------+-------+----------
 public | tbl_partition        | table | postgres
 public | tbl_partition_202011 | table | postgres
 public | tbl_partition_202012 | table | postgres
 public | tbl_partition_202101 | table | postgres
 public | tbl_partition_202102 | table | postgres
 public | tbl_partition_202103 | table | postgres
 public | tbl_partition_202104 | table | postgres
 public | tbl_partition_202105 | table | postgres
(8 rows)

postgres=## \d tbl_partition
                    Table "public.tbl_partition"
  Column   |         Type          | Collation | Nullable | Default
-----------+-----------------------+-----------+----------+---------
 id        | integer               |           |          |
 name      | character varying(20) |           |          |
 gender    | boolean               |           |          |
 join_date | date                  |           |          |
 dept      | character(4)          |           |          |
Number of child tables: 7 (Use \d+ to list them.)

postgres=## \d+ tbl_partition
                                        Table "public.tbl_partition"
  Column   |         Type          | Collation | Nullable | Default | Storage  | Stats target | Description
-----------+-----------------------+-----------+----------+---------+----------+--------------+-------------
 id        | integer               |           |          |         | plain    |              |
 name      | character varying(20) |           |          |         | extended |              |
 gender    | boolean               |           |          |         | plain    |              |
 join_date | date                  |           |          |         | plain    |              |
 dept      | character(4)          |           |          |         | extended |              |
Child tables: tbl_partition_202011,
              tbl_partition_202012,
              tbl_partition_202101,
              tbl_partition_202102,
              tbl_partition_202103,
              tbl_partition_202104,
              tbl_partition_202105
Access method: heap

postgres=## \d tbl_partition_202011
                Table "public.tbl_partition_202011"
  Column   |         Type          | Collation | Nullable | Default
-----------+-----------------------+-----------+----------+---------
 id        | integer               |           |          |
 name      | character varying(20) |           |          |
 gender    | boolean               |           |          |
 join_date | date                  |           |          |
 dept      | character(4)          |           |          |
Check constraints:
    "tbl_partition_202011_join_date_check" CHECK (join_date >= '2020-11-01'::date AND join_date < '2020-12-01'::date)
Inherits: tbl_partition

postgres=## \d

List of relations

Schema | Name | Type | Owner

--------+----------------------+-------+----------

public | tbl_partition | table | postgres

public | tbl_partition_202011 | table | postgres

public | tbl_partition_202012 | table | postgres

public | tbl_partition_202101 | table | postgres

public | tbl_partition_202102 | table | postgres

public | tbl_partition_202103 | table | postgres

public | tbl_partition_202104 | table | postgres

public | tbl_partition_202105 | table | postgres

(8 rows)

postgres=## \d tbl_partition

Table "public.tbl_partition"

Column | Type | Collation | Nullable | Default

-----------+-----------------------+-----------+----------+---------

id | integer | | |

name | character varying(20) | | |

gender | boolean | | |

join_date | date | | |

dept | character(4) | | |

Number of child tables: 7 (Use \d+ to list them.)

postgres=## \d+ tbl_partition

Table "public.tbl_partition"

-----------+-----------------------+-----------+----------+---------+----------+--------------+-------------

Child tables: tbl_partition_202011,

tbl_partition_202012,

tbl_partition_202101,

tbl_partition_202102,

tbl_partition_202103,

tbl_partition_202104,

tbl_partition_202105

Access method: heap

postgres=## \d tbl_partition_202011

Table "public.tbl_partition_202011"

Column | Type | Collation | Nullable | Default

-----------+-----------------------+-----------+----------+---------

id | integer | | |

name | character varying(20) | | |

gender | boolean | | |

join_date | date | | |

dept | character(4) | | |

Check constraints:

"tbl_partition_202011_join_date_check" CHECK (join_date >= '2020-11-01'::date AND join_date < '2020-12-01'::date)

Inherits: tbl_partition

3 分区键上建索引

create index tbl_partition_202011_joindate on tbl_partition_202011 (join_date);

create index tbl_partition_202012_joindate on tbl_partition_202012 (join_date); 

create index tbl_partition_202101_joindate on tbl_partition_202101 (join_date);    

create index tbl_partition_202102_joindate on tbl_partition_202102 (join_date); 

create index tbl_partition_202103_joindate on tbl_partition_202103 (join_date); 

create index tbl_partition_202104_joindate on tbl_partition_202104 (join_date); 

create index tbl_partition_202105_joindate on tbl_partition_202105 (join_date); 

postgres=## \d tbl_partition_202011
                Table "public.tbl_partition_202011"
  Column   |         Type          | Collation | Nullable | Default
-----------+-----------------------+-----------+----------+---------
 id        | integer               |           |          |
 name      | character varying(20) |           |          |
 gender    | boolean               |           |          |
 join_date | date                  |           |          |
 dept      | character(4)          |           |          |
Indexes:
    "tbl_partition_202011_joindate" btree (join_date)
Check constraints:
    "tbl_partition_202011_join_date_check" CHECK (join_date >= '2020-11-01'::date AND join_date < '2020-12-01'::date)
Inherits: tbl_partition

create index tbl_partition_202011_joindate on tbl_partition_202011 (join_date);

create index tbl_partition_202012_joindate on tbl_partition_202012 (join_date);

create index tbl_partition_202101_joindate on tbl_partition_202101 (join_date);

create index tbl_partition_202102_joindate on tbl_partition_202102 (join_date);

create index tbl_partition_202103_joindate on tbl_partition_202103 (join_date);

create index tbl_partition_202104_joindate on tbl_partition_202104 (join_date);

create index tbl_partition_202105_joindate on tbl_partition_202105 (join_date);

postgres=## \d tbl_partition_202011

Table "public.tbl_partition_202011"

Column | Type | Collation | Nullable | Default

-----------+-----------------------+-----------+----------+---------

id | integer | | |

name | character varying(20) | | |

gender | boolean | | |

join_date | date | | |

dept | character(4) | | |

Indexes:

"tbl_partition_202011_joindate" btree (join_date)

Check constraints:

"tbl_partition_202011_join_date_check" CHECK (join_date >= '2020-11-01'::date AND join_date < '2020-12-01'::date)

Inherits: tbl_partition

4 创建触发器函数

对于开发人员来说，希望数据库是透明的，只管 insert into tbl_partition。对于数据插向哪个分区，则希望由DB决定。这点，ORACLE实现了，但是PG不行，需要前期人工处理下。

CREATE OR REPLACE FUNCTION tbl_partition_insert_trigger()                      
RETURNS TRIGGER AS $$  
BEGIN  
    IF ( NEW.join_date >= DATE '2020-11-01' AND    
         NEW.join_date < DATE '2020-12-01' ) THEN  
        INSERT INTO tbl_partition_202011 VALUES (NEW.*);  
    ELSIF ( NEW.join_date >= DATE '2020-12-01' AND  
            NEW.join_date < DATE '2021-01-01' ) THEN  
        INSERT INTO tbl_partition_202012 VALUES (NEW.*);  
    ELSIF ( NEW.join_date >= DATE '2021-01-01' AND  
            NEW.join_date < DATE '2021-02-01' ) THEN  
        INSERT INTO tbl_partition_202101 VALUES (NEW.*);  
    ELSIF ( NEW.join_date >= DATE '2021-02-01' AND  
            NEW.join_date < DATE '2021-03-01' ) THEN  
        INSERT INTO tbl_partition_202102 VALUES (NEW.*);  
    ELSIF ( NEW.join_date >= DATE '2021-03-01' AND  
            NEW.join_date < DATE '2021-04-01' ) THEN  
        INSERT INTO tbl_partition_202103 VALUES (NEW.*);  
    ELSIF ( NEW.join_date >= DATE '2021-04-01' AND  
            NEW.join_date < DATE '2021-05-01' ) THEN  
        INSERT INTO tbl_partition_202104 VALUES (NEW.*);
    ELSIF ( NEW.join_date >= DATE '2021-05-01' AND
            NEW.join_date < DATE '2021-06-01' ) THEN
        INSERT INTO tbl_partition_202105 VALUES (NEW.*); 
    ELSE  
        RAISE EXCEPTION 'Date out of range. Fix the tbl_partition_insert_trigger() function!';  
    END IF;  
    RETURN NULL;  
END;  
$$  
LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION tbl_partition_insert_trigger()

RETURNS TRIGGER AS $$

BEGIN

IF ( NEW.join_date >= DATE '2020-11-01' AND

NEW.join_date < DATE '2020-12-01' ) THEN

INSERT INTO tbl_partition_202011 VALUES (NEW.*);

ELSIF ( NEW.join_date >= DATE '2020-12-01' AND

NEW.join_date < DATE '2021-01-01' ) THEN

INSERT INTO tbl_partition_202012 VALUES (NEW.*);

ELSIF ( NEW.join_date >= DATE '2021-01-01' AND

NEW.join_date < DATE '2021-02-01' ) THEN

INSERT INTO tbl_partition_202101 VALUES (NEW.*);

ELSIF ( NEW.join_date >= DATE '2021-02-01' AND

NEW.join_date < DATE '2021-03-01' ) THEN

INSERT INTO tbl_partition_202102 VALUES (NEW.*);

ELSIF ( NEW.join_date >= DATE '2021-03-01' AND

NEW.join_date < DATE '2021-04-01' ) THEN

INSERT INTO tbl_partition_202103 VALUES (NEW.*);

ELSIF ( NEW.join_date >= DATE '2021-04-01' AND

NEW.join_date < DATE '2021-05-01' ) THEN

INSERT INTO tbl_partition_202104 VALUES (NEW.*);

ELSIF ( NEW.join_date >= DATE '2021-05-01' AND

NEW.join_date < DATE '2021-06-01' ) THEN

INSERT INTO tbl_partition_202105 VALUES (NEW.*);

ELSE

RAISE EXCEPTION 'Date out of range. Fix the tbl_partition_insert_trigger() function!';

END IF;

RETURN NULL;

END;

LANGUAGE plpgsql;

说明：如果不想丢失数据，上面的ELSE 条件可以改成 INSERT INTO tbl_partition_error_join_date VALUES (NEW.*); 同时需要创建一张结构和tbl_partition 一样的表tbl_partition_error_join_date，这样，错误的join_date 数据就可以插入到这张表中而不是报错了。

5 创建触发器

 CREATE TRIGGER insert_tbl_partition_trigger
   BEFORE INSERT ON tbl_partition
 FOR EACH ROW EXECUTE PROCEDURE tbl_partition_insert_trigger();

CREATE TRIGGER insert_tbl_partition_trigger

BEFORE INSERT ON tbl_partition

FOR EACH ROW EXECUTE PROCEDURE tbl_partition_insert_trigger();

查看分区表

注意：通过这种方式创建的分区表，视图pg_partitioned_table不显示数据。

1 查看所有表

 \dt
                List of relations
 Schema |         Name         | Type  |  Owner   
--------+----------------------+-------+----------
 public | tbl_partition        | table | postgres
 public | tbl_partition_202011 | table | postgres
 public | tbl_partition_202012 | table | postgres
 public | tbl_partition_202101 | table | postgres
 public | tbl_partition_202102 | table | postgres
 public | tbl_partition_202103 | table | postgres
 public | tbl_partition_202104 | table | postgres
 public | tbl_partition_202105 | table | postgres
(8 rows)

\dt

List of relations

Schema | Name | Type | Owner

--------+----------------------+-------+----------

public | tbl_partition | table | postgres

public | tbl_partition_202011 | table | postgres

public | tbl_partition_202012 | table | postgres

public | tbl_partition_202101 | table | postgres

public | tbl_partition_202102 | table | postgres

public | tbl_partition_202103 | table | postgres

public | tbl_partition_202104 | table | postgres

public | tbl_partition_202105 | table | postgres

(8 rows)

2 查看主表

 \d tbl_partition
         Table "public.tbl_partition"
  Column   |         Type          | Modifiers 
-----------+-----------------------+-----------
 id        | integer               | 
 name      | character varying(20) | 
 gender    | boolean               | 
 join_date | date                  | 
 dept      | character(4)          | 
Triggers:
    insert_tbl_partition_trigger BEFORE INSERT ON tbl_partition FOR EACH ROW EXECUTE PROCEDURE tbl_partition_insert_trigger()
Number of child tables: 7 (Use \d+ to list them.)

\d tbl_partition

Table "public.tbl_partition"

Column | Type | Modifiers

-----------+-----------------------+-----------

id | integer |

name | character varying(20) |

gender | boolean |

join_date | date |

dept | character(4) |

Triggers:

insert_tbl_partition_trigger BEFORE INSERT ON tbl_partition FOR EACH ROW EXECUTE PROCEDURE tbl_partition_insert_trigger()

Number of child tables: 7 (Use \d+ to list them.)

3 查看分区表

 \d tbl_partition_202104
      Table "public.tbl_partition_202104"
  Column   |         Type          | Modifiers 
-----------+-----------------------+-----------
 id        | integer               | 
 name      | character varying(20) | 
 gender    | boolean               | 
 join_date | date                  | 
 dept      | character(4)          | 
Indexes:
    "tbl_partition_202104_joindate" btree (join_date)
Check constraints:
    "tbl_partition_202104_join_date_check" CHECK (join_date >= '2021-04-01'::date AND join_date < '2021-05-01'::date)
Inherits: tbl_partition

\d tbl_partition_202104

Table "public.tbl_partition_202104"

Column | Type | Modifiers

-----------+-----------------------+-----------

id | integer |

name | character varying(20) |

gender | boolean |

join_date | date |

dept | character(4) |

Indexes:

"tbl_partition_202104_joindate" btree (join_date)

Check constraints:

"tbl_partition_202104_join_date_check" CHECK (join_date >= '2021-04-01'::date AND join_date < '2021-05-01'::date)

Inherits: tbl_partition

测试

插入数据

 insert into tbl_partition values (1, 'David', '1', '2021-01-10', 'TS');
 insert into tbl_partition values (2, 'Sandy', '0', '2021-02-10', 'TS');
 insert into tbl_partition values (3, 'Eagle', '1', '2020-11-01', 'TS');
 insert into tbl_partition values (4, 'Miles', '1', '2020-12-15', 'SD');
 insert into tbl_partition values (5, 'Simon', '1', '2020-12-10', 'SD');
 insert into tbl_partition values (6, 'Rock', '1', '2020-11-10', 'SD');
 insert into tbl_partition values (7, 'Peter', '1', '2021-01-11', 'SD');
 insert into tbl_partition values (8, 'Sally', '0', '2021-03-10', 'BCSC');
 insert into tbl_partition values (9, 'Carrie', '0', '2021-04-02', 'BCSC');
 insert into tbl_partition values (10, 'Lee', '1', '2021-01-05', 'BMC');
 insert into tbl_partition values (11, 'Nicole', '0', '2020-11-10', 'PROJ');
 insert into tbl_partition values (12, 'Renee', '0', '2021-01-10', 'TS');

insert into tbl_partition values (1, 'David', '1', '2021-01-10', 'TS');

insert into tbl_partition values (2, 'Sandy', '0', '2021-02-10', 'TS');

insert into tbl_partition values (3, 'Eagle', '1', '2020-11-01', 'TS');

insert into tbl_partition values (4, 'Miles', '1', '2020-12-15', 'SD');

insert into tbl_partition values (5, 'Simon', '1', '2020-12-10', 'SD');

insert into tbl_partition values (6, 'Rock', '1', '2020-11-10', 'SD');

insert into tbl_partition values (7, 'Peter', '1', '2021-01-11', 'SD');

insert into tbl_partition values (8, 'Sally', '0', '2021-03-10', 'BCSC');

insert into tbl_partition values (9, 'Carrie', '0', '2021-04-02', 'BCSC');

insert into tbl_partition values (10, 'Lee', '1', '2021-01-05', 'BMC');

insert into tbl_partition values (11, 'Nicole', '0', '2020-11-10', 'PROJ');

insert into tbl_partition values (12, 'Renee', '0', '2021-01-10', 'TS');

查看主表数据

 select * from tbl_partition;
 id |  name  | gender | join_date  | dept 
----+--------+--------+------------+------
  3 | Eagle  | t      | 2020-11-01 | TS  
  6 | Rock   | t      | 2020-11-10 | SD  
 11 | Nicole | f      | 2020-11-10 | PROJ
  4 | Miles  | t      | 2020-12-15 | SD  
  5 | Simon  | t      | 2020-12-10 | SD  
  1 | David  | t      | 2021-01-10 | TS  
  7 | Peter  | t      | 2021-01-11 | SD  
 10 | Lee    | t      | 2021-01-05 | BMC 
 12 | Renee  | f      | 2021-01-10 | TS  
  2 | Sandy  | f      | 2021-02-10 | TS  
  8 | Sally  | f      | 2021-03-10 | BCSC
  9 | Carrie | f      | 2021-04-02 | BCSC
(12 rows)

select * from tbl_partition;

id | name | gender | join_date | dept

----+--------+--------+------------+------

3 | Eagle | t | 2020-11-01 | TS

6 | Rock | t | 2020-11-10 | SD

11 | Nicole | f | 2020-11-10 | PROJ

4 | Miles | t | 2020-12-15 | SD

5 | Simon | t | 2020-12-10 | SD

1 | David | t | 2021-01-10 | TS

7 | Peter | t | 2021-01-11 | SD

10 | Lee | t | 2021-01-05 | BMC

12 | Renee | f | 2021-01-10 | TS

2 | Sandy | f | 2021-02-10 | TS

8 | Sally | f | 2021-03-10 | BCSC

9 | Carrie | f | 2021-04-02 | BCSC

(12 rows)

查看分区表数据

 select * from tbl_partition_202101 ;
 id | name  | gender | join_date  | dept 
----+-------+--------+------------+------
  1 | David | t      | 2021-01-10 | TS  
  7 | Peter | t      | 2021-01-11 | SD  
 10 | Lee   | t      | 2021-01-05 | BMC 
 12 | Renee | f      | 2021-01-10 | TS  
(4 rows)

select * from tbl_partition_202101 ;

id | name | gender | join_date | dept

----+-------+--------+------------+------

1 | David | t | 2021-01-10 | TS

7 | Peter | t | 2021-01-11 | SD

10 | Lee | t | 2021-01-05 | BMC

12 | Renee | f | 2021-01-10 | TS

(4 rows)

PG 10 新特性

PG10之前实现分区表功能，基本是根据“继承表+约束+规则或触发器”实现，相对于之前的分区实现方式，PG10的分区特性有以下优势：
1）管理分区方便
2）数据插入效率高

注意：

主表和分区分别单独创建
范围分区支持多个字段组成的KEY
列表分区的KEY只能有一个字段

创建主表语法：

CREATE TABLE 表名 ( [{ 列名称 数据_类型} [, … ] ] )
PARTITION BY RANGE ( [{ 列名称 } [, …] ] ); 
范围分区的KEY值可由多个字段组成（最多32个字段）。

CREATE TABLE 表名 ( [{ 列名称数据_类型} [, … ] ] )

PARTITION BY RANGE ( [{ 列名称 } [, …] ] );

范围分区的KEY值可由多个字段组成（最多32个字段）。

创建分区语法：

CREATE TABLE 表名 PARTITION OF 主表 FOR VALUES
FROM{ ( 表达式 [, …] ) | MINVALUE } [, …]
TO { ( 表达式 [, …] ) | MAXVALUE } [, …] [ TABLESPACE 表空间名 ];

CREATE TABLE 表名 PARTITION OF 主表 FOR VALUES

FROM{ ( 表达式 [, …] ) | MINVALUE } [, …]

TO { ( 表达式 [, …] ) | MAXVALUE } [, …] [ TABLESPACE 表空间名 ];

参数说明:
// FROM … TO 表示分区的起始值和结束值。
// MINVALUE / MAXVALUE 表示无限小值和无限大值。
// 默认FROM后面的值是包括值分区的约束内，TO后面的值不包括。

范围分区

create table tbp(n int, t text) partition by range(n);
create table tbp_1 partition of tbp for values from (MINVALUE) to (10);
create table tbp_2 partition of tbp for values from (10) to (100);
create table tbp_3 partition of tbp for values from (100) to (1000);
create table tbp_4 partition of tbp for values from (1000) to (MAXVALUE);

lhrdb=## \d
               List of relations
 Schema | Name  |       Type        |  Owner
--------+-------+-------------------+----------
 public | tbp   | partitioned table | postgres
 public | tbp_1 | table             | postgres
 public | tbp_2 | table             | postgres
 public | tbp_3 | table             | postgres
 public | tbp_4 | table             | postgres
(5 rows)

lhrdb=## select * from pg_partitioned_table;
 partrelid | partstrat | partnatts | partdefid | partattrs | partclass | partcollation | partexprs
-----------+-----------+-----------+-----------+-----------+-----------+---------------+-----------
     41034 | r         |         1 |         0 | 1         | 1978      | 0             |
(1 row)

lhrdb=## \d+ tbp
                              Partitioned table "public.tbp"
 Column |  Type   | Collation | Nullable | Default | Storage  | Stats target | Description
--------+---------+-----------+----------+---------+----------+--------------+-------------
 n      | integer |           |          |         | plain    |              |
 t      | text    |           |          |         | extended |              |
Partition key: RANGE (n)
Partitions: tbp_1 FOR VALUES FROM (MINVALUE) TO (10),
            tbp_2 FOR VALUES FROM (10) TO (100),
            tbp_3 FOR VALUES FROM (100) TO (1000),
            tbp_4 FOR VALUES FROM (1000) TO (MAXVALUE)

-- 获取分区类型和KEY            
SELECT pg_get_partkeydef('tbp'::regclass); 

-- 获取分区范围
SELECT pg_get_partition_constraintdef('tbp_1'::regclass) ; 

lhrdb=## SELECT pg_get_partkeydef('tbp'::regclass);
 pg_get_partkeydef
-------------------
 RANGE (n)
(1 row)

lhrdb=## SELECT pg_get_partition_constraintdef('tbp_1'::regclass) ;
 pg_get_partition_constraintdef
--------------------------------
 ((n IS NOT NULL) AND (n < 10))
(1 row)

create table tbp(n int, t text) partition by range(n);

create table tbp_1 partition of tbp for values from (MINVALUE) to (10);

create table tbp_2 partition of tbp for values from (10) to (100);

create table tbp_3 partition of tbp for values from (100) to (1000);

create table tbp_4 partition of tbp for values from (1000) to (MAXVALUE);

lhrdb=## \d

List of relations

Schema | Name | Type | Owner

--------+-------+-------------------+----------

public | tbp | partitioned table | postgres

public | tbp_1 | table | postgres

public | tbp_2 | table | postgres

public | tbp_3 | table | postgres

public | tbp_4 | table | postgres

(5 rows)

lhrdb=## select * from pg_partitioned_table;

-----------+-----------+-----------+-----------+-----------+-----------+---------------+-----------

41034 | r | 1 | 0 | 1 | 1978 | 0 |

(1 row)

lhrdb=## \d+ tbp

Partitioned table "public.tbp"

--------+---------+-----------+----------+---------+----------+--------------+-------------

Partition key: RANGE (n)

Partitions: tbp_1 FOR VALUES FROM (MINVALUE) TO (10),

tbp_2 FOR VALUES FROM (10) TO (100),

tbp_3 FOR VALUES FROM (100) TO (1000),

tbp_4 FOR VALUES FROM (1000) TO (MAXVALUE)

-- 获取分区类型和KEY

SELECT pg_get_partkeydef('tbp'::regclass);

-- 获取分区范围

SELECT pg_get_partition_constraintdef('tbp_1'::regclass) ;

lhrdb=## SELECT pg_get_partkeydef('tbp'::regclass);

pg_get_partkeydef

-------------------

RANGE (n)

(1 row)

lhrdb=## SELECT pg_get_partition_constraintdef('tbp_1'::regclass) ;

pg_get_partition_constraintdef

--------------------------------

((n IS NOT NULL) AND (n < 10))

(1 row)

多个key：

create table test(n1 int, n2 int) partition by range(n1, n2);
create table test_1 partition of test for values from (0, 0) to (10, 100);
lhrdb=## \d+ test_1
                                  Table "public.test_1"
 Column |  Type   | Collation | Nullable | Default | Storage | Stats target | Description
--------+---------+-----------+----------+---------+---------+--------------+-------------
 n1     | integer |           |          |         | plain   |              |
 n2     | integer |           |          |         | plain   |              |
Partition of: test FOR VALUES FROM (0, 0) TO (10, 100)
Partition constraint: ((n1 IS NOT NULL) AND (n2 IS NOT NULL) AND ((n1 > 0) OR ((n1 = 0) AND (n2 >= 0))) AND ((n1 < 10) OR ((n1 = 10) AND (n2 < 100))))
Access method: heap

create table test(n1 int, n2 int) partition by range(n1, n2);

create table test_1 partition of test for values from (0, 0) to (10, 100);

lhrdb=## \d+ test_1

Table "public.test_1"

--------+---------+-----------+----------+---------+---------+--------------+-------------

Partition of: test FOR VALUES FROM (0, 0) TO (10, 100)

Partition constraint: ((n1 IS NOT NULL) AND (n2 IS NOT NULL) AND ((n1 > 0) OR ((n1 = 0) AND (n2 >= 0))) AND ((n1 < 10) OR ((n1 = 10) AND (n2 < 100))))

Access method: heap

n1范围从0到10，n2范围从0到100。

示例

create table test(n int) partition by range(n);
create table test_1 partition of test for values from (MINVALUE) to (10);
create table test_2 partition of test for values from (10) to (100);
create table test_3 partition of test for values from (100) to (1000);
create table test_4 partition of test for values from (1000) to (10000);

lhrdb3=## \d+ test
                             Partitioned table "public.test"
 Column |  Type   | Collation | Nullable | Default | Storage | Stats target | Description
--------+---------+-----------+----------+---------+---------+--------------+-------------
 n      | integer |           |          |         | plain   |              |
Partition key: RANGE (n)
Partitions: test_1 FOR VALUES FROM (MINVALUE) TO (10),
            test_2 FOR VALUES FROM (10) TO (100),
            test_3 FOR VALUES FROM (100) TO (1000),
            test_4 FOR VALUES FROM (1000) TO (10000)

lhrdb3=#
lhrdb3=## \d+ test_2
                                  Table "public.test_2"
 Column |  Type   | Collation | Nullable | Default | Storage | Stats target | Description
--------+---------+-----------+----------+---------+---------+--------------+-------------
 n      | integer |           |          |         | plain   |              |
Partition of: test FOR VALUES FROM (10) TO (100)
Partition constraint: ((n IS NOT NULL) AND (n >= 10) AND (n < 100))
Access method: heap

lhrdb3=## insert into test select generate_series(0, 9999);
INSERT 0 10000
lhrdb3=## explain analyze select * from test;
                                                  QUERY PLAN
---------------------------------------------------------------------------------------------------------------
 Append  (cost=0.00..337.75 rows=17850 width=4) (actual time=0.025..3.566 rows=10000 loops=1)
   ->  Seq Scan on test_1  (cost=0.00..35.50 rows=2550 width=4) (actual time=0.024..0.027 rows=10 loops=1)
   ->  Seq Scan on test_2  (cost=0.00..35.50 rows=2550 width=4) (actual time=0.017..0.028 rows=90 loops=1)
   ->  Seq Scan on test_3  (cost=0.00..35.50 rows=2550 width=4) (actual time=0.029..0.204 rows=900 loops=1)
   ->  Seq Scan on test_4  (cost=0.00..142.00 rows=10200 width=4) (actual time=0.029..2.049 rows=9000 loops=1)
 Planning Time: 0.175 ms
 Execution Time: 4.186 ms
(7 rows)

create table test(n int) partition by range(n);

create table test_1 partition of test for values from (MINVALUE) to (10);

create table test_2 partition of test for values from (10) to (100);

create table test_3 partition of test for values from (100) to (1000);

create table test_4 partition of test for values from (1000) to (10000);

lhrdb3=## \d+ test

Partitioned table "public.test"

--------+---------+-----------+----------+---------+---------+--------------+-------------

Partition key: RANGE (n)

Partitions: test_1 FOR VALUES FROM (MINVALUE) TO (10),

test_2 FOR VALUES FROM (10) TO (100),

test_3 FOR VALUES FROM (100) TO (1000),

test_4 FOR VALUES FROM (1000) TO (10000)

lhrdb3=#

lhrdb3=## \d+ test_2

Table "public.test_2"

--------+---------+-----------+----------+---------+---------+--------------+-------------

Partition of: test FOR VALUES FROM (10) TO (100)

Partition constraint: ((n IS NOT NULL) AND (n >= 10) AND (n < 100))

Access method: heap

lhrdb3=## insert into test select generate_series(0, 9999);

INSERT 0 10000

lhrdb3=## explain analyze select * from test;

QUERY PLAN

---------------------------------------------------------------------------------------------------------------

Append (cost=0.00..337.75 rows=17850 width=4) (actual time=0.025..3.566 rows=10000 loops=1)

-> Seq Scan on test_1 (cost=0.00..35.50 rows=2550 width=4) (actual time=0.024..0.027 rows=10 loops=1)

-> Seq Scan on test_2 (cost=0.00..35.50 rows=2550 width=4) (actual time=0.017..0.028 rows=90 loops=1)

-> Seq Scan on test_3 (cost=0.00..35.50 rows=2550 width=4) (actual time=0.029..0.204 rows=900 loops=1)

-> Seq Scan on test_4 (cost=0.00..142.00 rows=10200 width=4) (actual time=0.029..2.049 rows=9000 loops=1)

Planning Time: 0.175 ms

Execution Time: 4.186 ms

(7 rows)

列表分区

CREATE TABLE sales (product_id int, saleroom int, province text) PARTITION BY LIST(province);
CREATE TABLE sales_east PARTITION OF sales FOR VALUES IN ('山东','江苏','上海');
CREATE TABLE sales_west PARTITION OF sales FOR VALUES IN ('山西','陕西','四川');
CREATE TABLE sales_north PARTITION OF sales FOR VALUES IN ('北京','河北','辽宁');
CREATE TABLE sales_south PARTITION OF sales FOR VALUES IN ('广东','福建');

lhrdb2=## \dt
                  List of relations
 Schema |    Name     |       Type        |  Owner
--------+-------------+-------------------+----------
 public | sales       | partitioned table | postgres
 public | sales_east  | table             | postgres
 public | sales_north | table             | postgres
 public | sales_south | table             | postgres
 public | sales_west  | table             | postgres
(5 rows)

lhrdb2=## insert into sales values(1,1,'山东'),(2,2,'山西'),(3,3,'北京'),(4,4,'广东');
INSERT 0 4
lhrdb2=## select * from sales;
 product_id | saleroom | province
------------+----------+----------
          1 |        1 | 山东
          3 |        3 | 北京
          2 |        2 | 山西
          4 |        4 | 广东
(4 rows)

lhrdb2=## select * from sales_east;
 product_id | saleroom | province
------------+----------+----------
          1 |        1 | 山东
(1 row)

lhrdb2=## select * from sales_west;
 product_id | saleroom | province
------------+----------+----------
          2 |        2 | 山西
(1 row)

CREATE TABLE sales (product_id int, saleroom int, province text) PARTITION BY LIST(province);

CREATE TABLE sales_east PARTITION OF sales FOR VALUES IN ('山东','江苏','上海');

CREATE TABLE sales_west PARTITION OF sales FOR VALUES IN ('山西','陕西','四川');

CREATE TABLE sales_north PARTITION OF sales FOR VALUES IN ('北京','河北','辽宁');

CREATE TABLE sales_south PARTITION OF sales FOR VALUES IN ('广东','福建');

lhrdb2=## \dt

List of relations

Schema | Name | Type | Owner

--------+-------------+-------------------+----------

public | sales | partitioned table | postgres

public | sales_east | table | postgres

public | sales_north | table | postgres

public | sales_south | table | postgres

public | sales_west | table | postgres

(5 rows)

lhrdb2=## insert into sales values(1,1,'山东'),(2,2,'山西'),(3,3,'北京'),(4,4,'广东');

INSERT 0 4

lhrdb2=## select * from sales;

product_id | saleroom | province

------------+----------+----------

1 | 1 | 山东

3 | 3 | 北京

2 | 2 | 山西

4 | 4 | 广东

(4 rows)

lhrdb2=## select * from sales_east;

product_id | saleroom | province

------------+----------+----------

1 | 1 | 山东

(1 row)

lhrdb2=## select * from sales_west;

product_id | saleroom | province

------------+----------+----------

2 | 2 | 山西

(1 row)

绑定分区

分区表支持把普通表绑定成父表的一个分区，也支持把分区解绑为普通表。

若普通表中有数据，ATTACH操作时，默认会做数据校验。

CREATE TABLE sales_foreign (like sales);
ALTER TABLE sales ATTACH PARTITION sales_foreign FOR VALUES IN('美国','日本');

lhrdb2=## \d+ sales
                               Partitioned table "public.sales"
   Column   |  Type   | Collation | Nullable | Default | Storage  | Stats target | Description
------------+---------+-----------+----------+---------+----------+--------------+-------------
 product_id | integer |           |          |         | plain    |              |
 saleroom   | integer |           |          |         | plain    |              |
 province   | text    |           |          |         | extended |              |
Partition key: LIST (province)
Partitions: sales_east FOR VALUES IN ('山东', '江苏', '上海'),
            sales_foreign FOR VALUES IN ('美国', '日本'),
            sales_north FOR VALUES IN ('北京', '河北', '辽宁'),
            sales_south FOR VALUES IN ('广东', '福建'),
            sales_west FOR VALUES IN ('山西', '陕西', '四川')

lhrdb2=## ALTER TABLE sales DETACH PARTITION sales_foreign;
ALTER TABLE
lhrdb2=##  \d+ sales
                               Partitioned table "public.sales"
   Column   |  Type   | Collation | Nullable | Default | Storage  | Stats target | Description
------------+---------+-----------+----------+---------+----------+--------------+-------------
 product_id | integer |           |          |         | plain    |              |
 saleroom   | integer |           |          |         | plain    |              |
 province   | text    |           |          |         | extended |              |
Partition key: LIST (province)
Partitions: sales_east FOR VALUES IN ('山东', '江苏', '上海'),
            sales_north FOR VALUES IN ('北京', '河北', '辽宁'),
            sales_south FOR VALUES IN ('广东', '福建'),
            sales_west FOR VALUES IN ('山西', '陕西', '四川')

CREATE TABLE sales_foreign (like sales);

ALTER TABLE sales ATTACH PARTITION sales_foreign FOR VALUES IN('美国','日本');

lhrdb2=## \d+ sales

Partitioned table "public.sales"

------------+---------+-----------+----------+---------+----------+--------------+-------------

Partition key: LIST (province)

Partitions: sales_east FOR VALUES IN ('山东', '江苏', '上海'),

sales_foreign FOR VALUES IN ('美国', '日本'),

sales_north FOR VALUES IN ('北京', '河北', '辽宁'),

sales_south FOR VALUES IN ('广东', '福建'),

sales_west FOR VALUES IN ('山西', '陕西', '四川')

lhrdb2=## ALTER TABLE sales DETACH PARTITION sales_foreign;

ALTER TABLE

lhrdb2=## \d+ sales

Partitioned table "public.sales"

------------+---------+-----------+----------+---------+----------+--------------+-------------

Partition key: LIST (province)

Partitions: sales_east FOR VALUES IN ('山东', '江苏', '上海'),

sales_north FOR VALUES IN ('北京', '河北', '辽宁'),

sales_south FOR VALUES IN ('广东', '福建'),

sales_west FOR VALUES IN ('山西', '陕西', '四川')

查询

获取系统信息（系统表）：
pg_partitioned_table 记录主表信息的系统表：

分区的信息记录在pg_class相关的字段中：

PG 11新特性

PostgreSQL 11 为分区表功能提供更多的改进。这些特性包括：hash 分区、索引增强、DML改进，以及性能优化：faster partition pruning、run-time partition pruning,、partition-wise join。

pg11新增了hash partition
pg11中可以建立default partition(默认分区)
pg11中可以对partition key进行更新
pg11中在partitioned table(主表)上建立索引，索引会自动建立在partition(子表)上
pg11中可以在partitioned table上建立unique constraints
在pg11中attach分区时，会自动给该新分区建立唯一约束和索引
pg_partition_tree函数，返回分区表详细信息，例如分区名称、上一级分区名称、是否叶子结点、层级，层级为零表示顶层主表。
pg_partition_root函数用于当已知partition时查询出分区表顶层主表的名字
pg_partition_ancestors返回上层分区名称，包括本层分区名称。

hash分区语法

-- 主表
CREATE TABLE table_name ( column_name data_type )
    PARTITION BY HASH ( { column_name } [, ... ] )

-- 子表
CREATE TABLE table_name
    PARTITION OF parent_table 
FOR VALUES
    WITH ( MODULUS numeric_literal, REMAINDER numeric_literal )

-- 主表

CREATE TABLE table_name ( column_name data_type )

PARTITION BY HASH ( { column_name } [, ... ] )

-- 子表

CREATE TABLE table_name

PARTITION OF parent_table

FOR VALUES

WITH ( MODULUS numeric_literal, REMAINDER numeric_literal )

哈希分区支持多列分区，下面给出示例：

create table test_hash(id int, date date) 
  partition by hash(id);

create table test_hash_1 partition of test_hash 
  for values with(modulus 2, remainder 0);

create table test_hash_2 partition of test_hash 
  for values with(modulus 2, remainder 1);

\d+ test_hash
                                 Table "public.test_hash"
 Column |  Type   | Collation | Nullable | Default | Storage | Stats target | Description 
--------+---------+-----------+----------+---------+---------+--------------+-------------
 id     | integer |           |          |         | plain   |              | 
 date   | date    |           |          |         | plain   |              | 
Partition key: HASH (id)
Partitions: test_hash_1 FOR VALUES WITH (modulus 2, remainder 0),
            test_hash_2 FOR VALUES WITH (modulus 2, remainder 1)

\d+ test_hash_1 
                                Table "public.test_hash_1"
 Column |  Type   | Collation | Nullable | Default | Storage | Stats target | Description 
--------+---------+-----------+----------+---------+---------+--------------+-------------
 id     | integer |           |          |         | plain   |              | 
 date   | date    |           |          |         | plain   |              | 
Partition of: test_hash FOR VALUES WITH (modulus 2, remainder 0)
Partition constraint: satisfies_hash_partition('16603'::oid, 2, 0, id)

create table test_hash(id int, date date)

partition by hash(id);

create table test_hash_1 partition of test_hash

for values with(modulus 2, remainder 0);

create table test_hash_2 partition of test_hash

for values with(modulus 2, remainder 1);

\d+ test_hash

Table "public.test_hash"

--------+---------+-----------+----------+---------+---------+--------------+-------------

Partition key: HASH (id)

Partitions: test_hash_1 FOR VALUES WITH (modulus 2, remainder 0),

test_hash_2 FOR VALUES WITH (modulus 2, remainder 1)

\d+ test_hash_1

Table "public.test_hash_1"

--------+---------+-----------+----------+---------+---------+--------------+-------------

Partition of: test_hash FOR VALUES WITH (modulus 2, remainder 0)

Partition constraint: satisfies_hash_partition('16603'::oid, 2, 0, id)

示例2：

create table test_hash_key(x int, y int) 
  partition by hash(x,y);

create table test_hash_key_1 partition of test_hash_key 
  for values with(modulus 2, remainder 0);

create table test_hash_key_2 partition of test_hash_key 
  for values with(modulus 2, remainder 1);

\d+ test_hash_key
                               Table "public.test_hash_key"
 Column |  Type   | Collation | Nullable | Default | Storage | Stats target | Description 
--------+---------+-----------+----------+---------+---------+--------------+-------------
 x      | integer |           |          |         | plain   |              | 
 y      | integer |           |          |         | plain   |              | 
Partition key: HASH (x, y)
Partitions: test_hash_key_1 FOR VALUES WITH (modulus 2, remainder 0),
            test_hash_key_2 FOR VALUES WITH (modulus 2, remainder 1)

\d+ test_hash_key_1
                              Table "public.test_hash_key_1"
 Column |  Type   | Collation | Nullable | Default | Storage | Stats target | Description 
--------+---------+-----------+----------+---------+---------+--------------+-------------
 x      | integer |           |          |         | plain   |              | 
 y      | integer |           |          |         | plain   |              | 
Partition of: test_hash_key FOR VALUES WITH (modulus 2, remainder 0)
Partition constraint: satisfies_hash_partition('16561'::oid, 2, 0, x, y)

create table test_hash_key(x int, y int)

partition by hash(x,y);

create table test_hash_key_1 partition of test_hash_key

for values with(modulus 2, remainder 0);

create table test_hash_key_2 partition of test_hash_key

for values with(modulus 2, remainder 1);

\d+ test_hash_key

Table "public.test_hash_key"

--------+---------+-----------+----------+---------+---------+--------------+-------------

Partition key: HASH (x, y)

Partitions: test_hash_key_1 FOR VALUES WITH (modulus 2, remainder 0),

test_hash_key_2 FOR VALUES WITH (modulus 2, remainder 1)

\d+ test_hash_key_1

Table "public.test_hash_key_1"

--------+---------+-----------+----------+---------+---------+--------------+-------------

Partition of: test_hash_key FOR VALUES WITH (modulus 2, remainder 0)

Partition constraint: satisfies_hash_partition('16561'::oid, 2, 0, x, y)

默认分区

PostgreSQL 11新特性，防止插入失败，对于不符合分区约束的数据将会插入到默认分区。目前，range/list支持默认分区，hash分区不支持

语法：

CREATE TABLE table_name
    PARTITION OF parent_table 
FOR VALUES
    DEFAULT

CREATE TABLE table_name

PARTITION OF parent_table

FOR VALUES

DEFAULT

示例：

-- range
create table test_range_default partition of test_range  default;

\d+ test_range
                                Table "public.test_range"
 Column |  Type   | Collation | Nullable | Default | Storage | Stats target | Description 
--------+---------+-----------+----------+---------+---------+--------------+-------------
 id     | integer |           |          |         | plain   |              | 
 date   | date    |           |          |         | plain   |              | 
Partition key: RANGE (date)
Partitions: test_range_201801 FOR VALUES FROM ('2018-01-01') TO ('2018-02-01'),
            test_range_201802 FOR VALUES FROM ('2018-02-01') TO ('2018-03-01'),
            test_range_default DEFAULT

\d+ test_range_default 
                            Table "public.test_range_default"
 Column |  Type   | Collation | Nullable | Default | Storage | Stats target | Description 
--------+---------+-----------+----------+---------+---------+--------------+-------------
 id     | integer |           |          |         | plain   |              | 
 date   | date    |           |          |         | plain   |              | 
Partition of: test_range DEFAULT
Partition constraint: (NOT ((date IS NOT NULL) AND (((date >= '2018-01-01'::date) AND (date < '2018-02-01'::date)) OR ((date >= '2018-02-01'::date) AND (date < '2018-03-01'::date)))))

-- list
create table test_list_default partition of test_list  default;

\d+ test_list
                                 Table "public.test_list"
 Column |  Type   | Collation | Nullable | Default | Storage  | Stats target | Description 
--------+---------+-----------+----------+---------+----------+--------------+-------------
 id     | integer |           |          |         | plain    |              | 
 city   | text    |           |          |         | extended |              | 
Partition key: LIST (city)
Partitions: test_list_hz FOR VALUES IN ('杭州'),
            test_list_jn FOR VALUES IN ('济南'),
            test_list_default DEFAULT

\d+ test_list_default 
                             Table "public.test_list_default"
 Column |  Type   | Collation | Nullable | Default | Storage  | Stats target | Description 
--------+---------+-----------+----------+---------+----------+--------------+-------------
 id     | integer |           |          |         | plain    |              | 
 city   | text    |           |          |         | extended |              | 
Partition of: test_list DEFAULT
Partition constraint: (NOT ((city IS NOT NULL) AND (city = ANY (ARRAY['杭州'::text, '济南'::text]))))

-- hash
create table test_hash_default partition of test_hash  default;
ERROR:  a hash-partitioned table may not have a default partition

-- range

create table test_range_default partition of test_range default;

\d+ test_range

Table "public.test_range"

--------+---------+-----------+----------+---------+---------+--------------+-------------

Partition key: RANGE (date)

Partitions: test_range_201801 FOR VALUES FROM ('2018-01-01') TO ('2018-02-01'),

test_range_201802 FOR VALUES FROM ('2018-02-01') TO ('2018-03-01'),

test_range_default DEFAULT

\d+ test_range_default

Table "public.test_range_default"

--------+---------+-----------+----------+---------+---------+--------------+-------------

Partition of: test_range DEFAULT

Partition constraint: (NOT ((date IS NOT NULL) AND (((date >= '2018-01-01'::date) AND (date < '2018-02-01'::date)) OR ((date >= '2018-02-01'::date) AND (date < '2018-03-01'::date)))))

-- list

create table test_list_default partition of test_list default;

\d+ test_list

Table "public.test_list"

--------+---------+-----------+----------+---------+----------+--------------+-------------

Partition key: LIST (city)

Partitions: test_list_hz FOR VALUES IN ('杭州'),

test_list_jn FOR VALUES IN ('济南'),

test_list_default DEFAULT

\d+ test_list_default

Table "public.test_list_default"

--------+---------+-----------+----------+---------+----------+--------------+-------------

Partition of: test_list DEFAULT

Partition constraint: (NOT ((city IS NOT NULL) AND (city = ANY (ARRAY['杭州'::text, '济南'::text]))))

-- hash

create table test_hash_default partition of test_hash default;

ERROR: a hash-partitioned table may not have a default partition

默认分区可以防止插入失败：

insert into test_list values (3, '北京');

select *, tableoid::regclass from test_list;
 id | city |     tableoid      
----+------+-------------------
  1 | 杭州 | test_list_hz
  2 | 济南 | test_list_jn
  3 | 北京 | test_list_default
(3 rows)

insert into test_list values (3, '北京');

select *, tableoid::regclass from test_list;

id | city | tableoid

----+------+-------------------

1 | 杭州 | test_list_hz

2 | 济南 | test_list_jn

3 | 北京 | test_list_default

(3 rows)

多级分区

create table test_range_list(id int, city text, date date) 
  partition by list (city);

create table test_range_list_jn partition of test_range_list 
  for values in ('济南') 
  partition by range(date);

create table test_range_list_hz partition of test_range_list 
  for values in ('杭州') 
  partition by range(date);

create table test_range_list_jn_201801 partition of test_range_list_jn 
  for values from ('2018-01-01') to ('2018-02-01');

create table test_range_list_jn_201802 partition of test_range_list_jn 
  for values from ('2018-02-01') to ('2018-03-01');

create table test_range_list_hz_201801 partition of test_range_list_hz 
  for values from ('2018-01-01') to ('2018-02-01');

create table test_range_list_hz_201802 partition of test_range_list_hz 
  for values from ('2018-02-01') to ('2018-03-01');

\d+ test_range_list
                              Table "public.test_range_list"
 Column |  Type   | Collation | Nullable | Default | Storage  | Stats target | Description 
--------+---------+-----------+----------+---------+----------+--------------+-------------
 id     | integer |           |          |         | plain    |              | 
 city   | text    |           |          |         | extended |              | 
 date   | date    |           |          |         | plain    |              | 
Partition key: LIST (city)
Partitions: test_range_list_hz FOR VALUES IN ('杭州'), PARTITIONED,
            test_range_list_jn FOR VALUES IN ('济南'), PARTITIONED

\d+ test_range_list_jn
                             Table "public.test_range_list_jn"
 Column |  Type   | Collation | Nullable | Default | Storage  | Stats target | Description 
--------+---------+-----------+----------+---------+----------+--------------+-------------
 id     | integer |           |          |         | plain    |              | 
 city   | text    |           |          |         | extended |              | 
 date   | date    |           |          |         | plain    |              | 
Partition of: test_range_list FOR VALUES IN ('济南')
Partition constraint: ((city IS NOT NULL) AND (city = '济南'::text))
Partition key: RANGE (date)
Partitions: test_range_list_jn_201801 FOR VALUES FROM ('2018-01-01') TO ('2018-02-01'),
            test_range_list_jn_201802 FOR VALUES FROM ('2018-02-01') TO ('2018-03-01')

\d+ test_range_list_jn_201801 
                         Table "public.test_range_list_jn_201801"
 Column |  Type   | Collation | Nullable | Default | Storage  | Stats target | Description 
--------+---------+-----------+----------+---------+----------+--------------+-------------
 id     | integer |           |          |         | plain    |              | 
 city   | text    |           |          |         | extended |              | 
 date   | date    |           |          |         | plain    |              | 
Partition of: test_range_list_jn FOR VALUES FROM ('2018-01-01') TO ('2018-02-01')
Partition constraint: ((city IS NOT NULL) AND (city = '济南'::text) AND (date IS NOT NULL) AND (date >= '2018-01-01'::date) AND (date < '2018-02-01'::date))

create table test_range_list(id int, city text, date date)

partition by list (city);

create table test_range_list_jn partition of test_range_list

for values in ('济南')

partition by range(date);

create table test_range_list_hz partition of test_range_list

for values in ('杭州')

partition by range(date);

create table test_range_list_jn_201801 partition of test_range_list_jn

for values from ('2018-01-01') to ('2018-02-01');

create table test_range_list_jn_201802 partition of test_range_list_jn

for values from ('2018-02-01') to ('2018-03-01');

create table test_range_list_hz_201801 partition of test_range_list_hz

for values from ('2018-01-01') to ('2018-02-01');

create table test_range_list_hz_201802 partition of test_range_list_hz

for values from ('2018-02-01') to ('2018-03-01');

\d+ test_range_list

Table "public.test_range_list"

--------+---------+-----------+----------+---------+----------+--------------+-------------

Partition key: LIST (city)

Partitions: test_range_list_hz FOR VALUES IN ('杭州'), PARTITIONED,

test_range_list_jn FOR VALUES IN ('济南'), PARTITIONED

\d+ test_range_list_jn

Table "public.test_range_list_jn"

--------+---------+-----------+----------+---------+----------+--------------+-------------

Partition of: test_range_list FOR VALUES IN ('济南')

Partition constraint: ((city IS NOT NULL) AND (city = '济南'::text))

Partition key: RANGE (date)

Partitions: test_range_list_jn_201801 FOR VALUES FROM ('2018-01-01') TO ('2018-02-01'),

test_range_list_jn_201802 FOR VALUES FROM ('2018-02-01') TO ('2018-03-01')

\d+ test_range_list_jn_201801

Table "public.test_range_list_jn_201801"

--------+---------+-----------+----------+---------+----------+--------------+-------------

Partition of: test_range_list_jn FOR VALUES FROM ('2018-01-01') TO ('2018-02-01')

Partition constraint: ((city IS NOT NULL) AND (city = '济南'::text) AND (date IS NOT NULL) AND (date >= '2018-01-01'::date) AND (date < '2018-02-01'::date))

ATTACH/DETACH 分区

语法：

ALTER TABLE name
    ATTACH PARTITION partition_name { FOR VALUES partition_bound_spec | DEFAULT }

ALTER TABLE name
    DETACH PARTITION partition_name

ALTER TABLE name

ATTACH PARTITION partition_name { FOR VALUES partition_bound_spec | DEFAULT }

ALTER TABLE name

DETACH PARTITION partition_name

以hash分区示例进行演示

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合 PG中的分区表

表分区简介

传统方式实现分区

创建分区表

1 创建主表

2 创建分区表

3 分区键上建索引

4 创建触发器函数

5 创建触发器

查看分区表

1 查看所有表

2 查看主表

3 查看分区表

测试

插入数据

查看主表数据

查看分区表数据

PG 10 新特性

范围分区

示例

列表分区

绑定分区

查询

PG 11新特性

hash分区语法

默认分区

多级分区

ATTACH/DETACH 分区

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合 PG中的分区表

表分区简介

传统方式实现分区

创建分区表

1 创建主表

2 创建分区表

3 分区键上建索引

4 创建触发器函数

5 创建触发器

查看分区表

1 查看所有表

2 查看主表

3 查看分区表

测试

插入数据

查看主表数据

查看分区表数据

PG 10 新特性

范围分区

示例

列表分区

绑定分区

查询

PG 11新特性

hash分区语法

默认分区

多级分区

ATTACH/DETACH 分区

相关文章

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