postgresql 中間件pgoneproxy支持範圍(range）分庫分表

    今天來給你們講解下postgresql數據庫的商業中間件pgoneproxy支持範圍分表的問題。這種分表的方式在不少場景中會被使用到。好比在電商，電信等行業，須要把每月的數據存放到不一樣的月份，就可使用range這個功能。

    先看看針對一級分表的狀況下的配置狀況：

[
	{
        "table":"trange",
        "pkey" : "id",
        "type" : "int",
        "method": "range",
        "partitions":
        [
           {"suffix":"_100", "value": "100", "group":"data1"}, 
           {"suffix":"_1000", "value":"1000", "group":"data1"}
        ]  

  }
]

上面配置的含義是：id<100的存放到trange_100這張表中，id >=100而且id < 1000的數據存放到trange_1000的表中。

若是須要根據時間來配置範圍，則須要修改type爲timestamp。再修改value爲對應的時間便可。

在不少場景中須要二級分表，好比在電商行業中，須要把用戶編號爲0結尾的用戶在7月份產生的訂單放到以_0_201607結尾的表中。下面講解的例子沒有以這種場景來說解，舉了用戶註冊信息的例子，一樣按照用戶編號和年份分割。配置以下所示：

[
  {
        "table" :"bigrange",
        "pkey"  : "id",
        "type"  : "int",
        "method" : "crc32",
        "partitions" :
         [
            {"suffix":"_0", "group":"data1"},
            {"suffix":"_1", "group":"data1"}
         ],
        "subpkey":"tt",
        "subtype":"timestamp",
        "submethod":"range",
        "subpartitions":
        [
           {"suffix":"_2015", "value":"2015-01-01 00:00:00"},
           {"suffix":"_2016", "value":"2016-01-01 00:00:01"}
        ]
  }
]

經過上面的配置來建立bigrange 表，則能夠獲得以下所示的表：

pgbench=> \dt;
              List of relations
 Schema |       Name       | Type  |  Owner   
--------+------------------+-------+----------
 public | bigrange_0_2015  | table | db_user
 public | bigrange_0_2016  | table | db_user
 public | bigrange_1_2015  | table | db_user
 public | bigrange_1_2016  | table | db_user

    根據配置是須要把在2015-01-01 00:00:00之前的用戶放到bigrange_0_2015或者bigrang_1_2015的兩張表中。在2015-01-01 00:00:01~2016-01-01 00:00:01註冊的用戶存放到bigrange_0_2016, bigrange_1_2016的兩張表中。

下面是簡單的操做bigrange表的狀況：

pgbench=> create table bigrange(id int, name varchar(32), age int, tt timestamp);
CREATE 0
pgbench=> insert into bigrange(id, name, age, tt) values(0, 'name0', 100, '2013-01-01 00:00:01');
INSERT 0 1
pgbench=> insert into bigrange(id, name, age, tt) values(1, 'name1', 100, '2014-01-01 00:00:01');
INSERT 0 1
pgbench=> insert into bigrange(id, name, age, tt) values(2, 'name2', 102, '2015-01-01 00:00:00');
INSERT 0 1
pgbench=> insert into bigrange(id, name, age, tt) values(3, 'name3', 103, '2016-01-01 00:00:00');
INSERT 0 1
pgbench=> insert into bigrange(id, name, age, tt) values(4, 'name4', 104, '2017-01-01 00:00:00');
ERROR:  Partitioned tables should choose at least one partition!
pgbench=> insert into bigrange(id, name, age, tt) values(4, 'name4', 104, '2015-01-01 03:00:00');
INSERT 0 1
pgbench=> select * from bigrang_0_2015;
ERROR:  relation "bigrang_0_2015" does not exist
LINE 1: select * from bigrang_0_2015;
                      ^
pgbench=> \dt;
              List of relations
 Schema |       Name       | Type  |  Owner   
--------+------------------+-------+----------
 public | bigrange_0_2015  | table | db_user
 public | bigrange_0_2016  | table | db_user
 public | bigrange_1_2015  | table | db_user
 public | bigrange_1_2016  | table | db_user
(4 rows)

pgbench=> select * from bigrange_0_2015;
 id | name  | age |         tt          
----+-------+-----+---------------------
  0 | name0 | 100 | 2013-01-01 00:00:01
(1 row)

pgbench=> select * from bigrange_1_2015;
 id | name  | age |         tt          
----+-------+-----+---------------------
  1 | name1 | 100 | 2014-01-01 00:00:01
(1 row)

pgbench=> select * from bigrange_0_2016;
 id | name  | age |         tt          
----+-------+-----+---------------------
  2 | name2 | 102 | 2015-01-01 00:00:00
  4 | name4 | 104 | 2015-01-01 03:00:00
(2 rows)

pgbench=> select * from bigrange_1_2016;
 id | name  | age |         tt          
----+-------+-----+---------------------
  3 | name3 | 103 | 2016-01-01 00:00:00
(1 row)

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