PostgreSQL 9.3 以後出現了物化視圖。物化視圖是由實實在在的數據組成，這是和一般視圖的根本區別。

1. 物化視圖創建語法如下：

--創建語法
CREATE MATERIALIZED VIEW table_name
    [ (column_name [, ...] ) ]
    [ WITH ( storage_parameter [= value] [, ... ] ) ]
    [ TABLESPACE tablespace_name ]
    AS query
    [ WITH [ NO ] DATA ]

--刷新語法
REFRESH MATERIALIZED VIEW
 
 [ CONCURRENTLY ] name
    [ WITH [ NO ] DATA ]

2. 創建物化視圖示例

--創建測試表
test=# CREATE TABLE TEST01 (ID INT);
CREATE TABLE
test=# INSERT INTO TEST01 SELECT GENERATE_SERIES(1,1000000);
INSERT 0 1000000

--創建物化視圖
test=# CREATE MATERIALIZED VIEW V_TEST01 AS SELECT * FROM TEST01;
SELECT 1000000
test=# 
test=# INSERT
 
 INTO TEST01 VALUES (1000001);
INSERT 0 1
test=# \timing
Timing is on.

--不加CONCURRENTLY參數的刷新
test=# REFRESH MATERIALIZED VIEW V_TEST01;
REFRESH MATERIALIZED VIEW
Time: 1888.860 ms
test=# INSERT INTO TEST01 VALUES (1000002);
INSERT 0 1
test=# CREATE UNIQUE INDEX INX_ID ON V_TEST01(ID);
CREATE INDEX

--
 
加CONCURRENTLY參數的刷新
test=# refresh materialized view concurrently v_test01;
REFRESH MATERIALIZED VIEW
Time: 100476.707 ms

可見，加了CONCRRENTLY參數後，刷新時間明顯增加。但加了CONCRRENTLY參數的更新不會阻塞查詢操作。

The End！

2017-08-21

【PostgreSQL】物化視圖