pgSql分区表新建及过程（BBB,ZJLJB）
--创建主表
CREATE TABLE zero_main ( --主表
city_id int NOT NULL,
logdate date NOT NULL,
peaktemp int
);
--创建几个分区表
CREATE TABLE zero_main_201710 ( ) INHERITS (zero_main);
CREATE TABLE zero_main_201711 ( ) INHERITS (zero_main);
CREATE TABLE zero_main_201712 ( ) INHERITS (zero_main);
CREATE TABLE zero_main_201801 ( ) INHERITS (zero_main);
CREATE TABLE zero_main_201802 ( ) INHERITS (zero_main);
CREATE TABLE zero_main_201803 ( ) INHERITS (zero_main);
--创建几个分区表（以时间logdate为约束条件）
CREATE TABLE zero_main_201710 (
CHECK ( logdate >= DATE '2017-10-01' AND logdate < DATE '2017-11-01')
) INHERITS (zero_main);
CREATE TABLE zero_main_201711 (
CHECK (logdate >= DATE '2017-11-01' AND logdate < DATE '2017-12-01')
) INHERITS (zero_main);
CREATE TABLE zero_main_201712 (
CHECK (logdate >= DATE '2017-12-01' AND logdate < DATE '2018-01-01')
) INHERITS (zero_main);
CREATE TABLE zero_main_201801 (
CHECK (logdate >= DATE '2018-01-01' AND logdate < DATE '2018-02-01')
) INHERITS (zero_main);
CREATE TABLE zero_main_201802 (
CHECK (logdate >= DATE '2018-02-01' AND logdate < DATE '2018-03-01')
) INHERITS (zero_main);
CREATE TABLE zero_main_201803 (
CHECK (logdate >= DATE '2018-03-01' AND logdate < DATE '2018-04-01')
) INHERITS (zero_main);
--创建索引
CREATE INDEX zero_main_201710_logdate ON zero_main_201710 (logdate);
CREATE INDEX zero_main_201711_logdate ON zero_main_201711 (logdate);
CREATE INDEX zero_main_201712_logdate ON zero_main_201712 (logdate);
CREATE INDEX zero_main_201801_logdate ON zero_main_201801 (logdate);
CREATE INDEX zero_main_201802_logdate ON zero_main_201802 (logdate);
CREATE INDEX zero_main_201803_logdate ON zero_main_201803 (logdate);
--定义一个规则或者触发器，把对主表的修改重定向到适当的分区表。
CREATE RULE zero_main_insert_201710 AS
ON INSERT TO zero_main WHERE (logdate >= DATE '2017-10-01' AND logdate < DATE '2017-11-01')
DO INSTEAD
INSERT INTO zero_main_201710 VALUES (NEW.city_id, NEW.logdate, NEW.peaktemp);
CREATE RULE zero_main_insert_201711 AS
ON INSERT TO zero_main WHERE (logdate >= DATE '2017-11-01' AND logdate < DATE '2017-12-01')
DO INSTEAD
INSERT INTO zero_main_201711 VALUES (NEW.city_id, NEW.logdate, NEW.peaktemp);
CREATE RULE zero_main_insert_201712 AS
ON INSERT TO zero_main WHERE (logdate >= DATE '2017-12-01' AND logdate < DATE '2018-01-01')
DO INSTEAD
INSERT INTO zero_main_201712 VALUES (NEW.city_id, NEW.logdate, NEW.peaktemp);
CREATE RULE zero_main_insert_201801 AS
ON INSERT TO zero_main WHERE (logdate >= DATE '2018-01-01' AND logdate < DATE '2018-02-01')
DO INSTEAD
INSERT INTO zero_main_201801 VALUES (NEW.city_id, NEW.logdate, NEW.peaktemp);
CREATE RULE zero_main_insert_201802 AS
ON INSERT TO zero_main WHERE (logdate >= DATE '2018-02-01' AND logdate < DATE '2018-03-01')
DO INSTEAD
INSERT INTO zero_main_201802 VALUES (NEW.city_id, NEW.logdate, NEW.peaktemp);
CREATE RULE zero_main_insert_201803 AS
ON INSERT TO zero_main WHERE (logdate >= DATE '2018-03-01' AND logdate < DATE '2018-04-01')
DO INSTEAD
INSERT INTO zero_main_201803 VALUES (NEW.city_id, NEW.logdate, NEW.peaktemp);
--创建新分区
/* 创建一个独立的数据表(zero_main_201804)，该表在创建时以将来的主表(zero_main)为模板，包含模板表的缺省值(DEFAULTS)和一致性约束(CONSTRAINTS)。*/
CREATE TABLE zero_main_201804
(LIKE zero_main INCLUDING DEFAULTS INCLUDING CONSTRAINTS);
/* 为该表创建未来作为子表时需要使用的检查约束。*/
ALTER TABLE zero_main_201804 ADD CONSTRAINT 201804
CHECK (logdate >= DATE '2018-04-01' AND logdate < DATE '2018-05-01');
/* 导入数据到该表。下面只是给出一种导入数据的方式作为例子。在导入数据之后，如有可能，还可以做进一步的数据处理，如数据转换、过滤等。*/
\copy measurement_y2008m02 from 'measurement_y2008m02'
/* 在适当的时候，或者说在需要的时候，让该表继承主表。*/
ALTER TABLE measurement_y2008m02 INHERIT measurement;
--约束排除
你可以使用EXPLAIN命令显示一个规划在constraint_exclusion打开和关闭情况下的不同。用上面方法设置的表的典型的缺省规划是：
SET constraint_exclusion = off;
EXPLAIN SELECT count(*) FROM measurement WHERE logdate >= DATE '2006-01-01';
SET constraint_exclusion = on;
EXPLAIN SELECT count(*) FROM measurement WHERE logdate >= DATE '2006-01-01';
--测试
INSERT INTO public.zero_main(
city_id, logdate, peaktemp)
VALUES (1, '2017-11-13 12:13:11', 2);
INSERT INTO public.zero_main(
city_id, logdate, peaktemp)
VALUES (2, '2017-12-13 12:13:11', 3);
INSERT INTO public.zero_main(
city_id, logdate, peaktemp)
VALUES (3, '2018-01-13 12:13:11', 4);
INSERT INTO public.zero_main(
city_id, logdate, peaktemp)
VALUES (4, '2018-02-13 12:13:11', 5);
INSERT INTO public.zero_main(
city_id, logdate, peaktemp)
VALUES (4, '2017-09-13 12:13:11', 5);
INSERT INTO public.zero_main(
city_id, logdate, peaktemp)
VALUES (4, '2018-05-13 12:13:11', 5);
select * from zero_main where logdate >= DATE '2018-02-01' and logdate < DATE '2018-03-01'
SET constraint_exclusion = off;
EXPLAIN SELECT count(*) FROM zero_main WHERE logdate >= DATE '2006-01-01';
SET constraint_exclusion = on;
EXPLAIN SELECT count(*) FROM zero_main WHERE logdate >= DATE '2006-01-01';