[Postgres]关于Postgres的INHERIT，分表

实在是很强大的功能

可以通过Check的制约把结构相同的表合并起来，或者反过来说，可以在一个表名下数据库自动的根据Check条件往对应的分表里存储数据

[USER_DATA表]

CREATE TABLE test."USER_DATA"
(
"MAC" character varying(12) NOT NULL,
"ID" character(3) NOT NULL,
"YEARS" numeric(6,0) NOT NULL,
"DAY" numeric(2,0) NOT NULL,
"HOUR" numeric(2,0) NOT NULL,
CONSTRAINT "USER_DATA_pkey" PRIMARY KEY ("MAC", "ID", "YEARS", "DAY", "HOUR")
)

[USER_DATA]的分表1[USER_DATA_201310]

CREATE TABLE test."USER_DATA_201310"
(
-- Inherit from table test."USER_DATA": "MAC" character varying(12) NOT NULL,
-- Inherit from table test."USER_DATA": "ID" character(3) NOT NULL,
-- Inherit from table test."USER_DATA": "YEARS" numeric(6,0) NOT NULL,
-- Inherit from table test."USER_DATA": "DAY" numeric(2,0) NOT NULL,
-- Inherit from table test."USER_DATA": "HOUR" numeric(2,0) NOT NULL,
CONSTRAINT "USER_DATA_201210_pkey" PRIMARY KEY ("MAC", "ID", "YEARS", "DAY", "HOUR"),
CONSTRAINT "USER_DATA_YEARS_check" CHECK ("YEARS" = 201310::numeric)
)
INHERITS (test."USER_DATA")

[USER_DATA]的分表2[USER_DATA_201311]

CREATE TABLE test."USER_DATA_201311"
(
-- Inherit from table test."USER_DATA": "MAC" character varying(12) NOT NULL,
-- Inherit from table test."USER_DATA": "ID" character(3) NOT NULL,
-- Inherit from table test."USER_DATA": "YEARS" numeric(6,0) NOT NULL,
-- Inherit from table test."USER_DATA": "DAY" numeric(2,0) NOT NULL,
-- Inherit from table test."USER_DATA": "HOUR" numeric(2,0) NOT NULL,
CONSTRAINT "USER_DATA_201210_pkey" PRIMARY KEY ("MAC", "ID", "YEARS", "DAY", "HOUR"),
CONSTRAINT "USER_DATA_YEARS_check" CHECK ("YEARS" = 201311::numeric)
)
INHERITS (test."USER_DATA")

通过CHECK ("YEARS" = 2013xx::numeric)来把往表[USER_DATA]上存储的数据自动的存储到分表1[USER_DATA_201310]或者分表2[USER_DATA_201311]上

这样做不仅可以降低单表的数据量，而且可以方便的拆分，组合，更方便的是，取数据的时候只用去访问[USER_DATA]表，就可以查询所有分表里的数据

组合

ALTER TABLE test."USER_DATA_201312" INHERIT test."USER_DATA"

拆分

ALTER TABLE test."USER_DATA_201310" NO INHERIT test."USER_DATA"