PostgreSQL 9.3物化视图使用


PostgreSQL 9.3物化视图使用
 
物化视图在Oracle里面是很早就内置的一个功能，而PostgreSQL也很早就将功能代码做出来，方式是类似create table as....，只是一直没有内置，9.3版本终于将此作为一个内置的功能点来使用，下面分享下最新版本的物化视图使用。 
 
目前postgres9.3在官网上有4个安装包，分别是9.3.0(stable version)、9.3.0 beta1、9.3.0betal2和9.3.0rc版本(release candidate version)，所以我们下载稳定的9.3.0 stable版本。 
 
下载地址： http://www.postgresql.org/ftp/source/v9.3.0/ 
安装略。 
 
一、语法
CREATE MATERIALIZED VIEW table_name
    [ (column_name [, ...] ) ]
    [ WITH ( storage_parameter [= value] [, ... ] ) ]
    [ TABLESPACE tablespace_name ]
    AS query
    [ WITH [ NO ] DATA ]
二、说明 
storage_parameter是存储参数，诸如填充因子(fillfactor)等,tablespace可以指定表空间,比较关键的是后面的as query with [no] data,后面示例描述 
 
三、示例 
 
1.创建基础表
[postgres@primary ~]$ psql
psql (9.3.0)
Type "help" for help.
 
postgres=# create table test_kenyon(id int,vname text);                                                 
CREATE TABLE
postgres=# insert into test_kenyon select generate_series(1,20),'kenyon good boy'||generate_series(1,20);
INSERT 0 20
postgres=# select * from test_kenyon ;
 id |       vname       
----+-------------------
  1 | kenyon good boy1
  2 | kenyon good boy2
  3 | kenyon good boy3
  4 | kenyon good boy4
  5 | kenyon good boy5
  6 | kenyon good boy6
  7 | kenyon good boy7
  8 | kenyon good boy8
  9 | kenyon good boy9
 10 | kenyon good boy10
 11 | kenyon good boy11
 12 | kenyon good boy12
 13 | kenyon good boy13
 14 | kenyon good boy14
 15 | kenyon good boy15
 16 | kenyon good boy16
 17 | kenyon good boy17
 18 | kenyon good boy18
 19 | kenyon good boy19
 20 | kenyon good boy20
(20 rows)
2.创建物化视图
postgres=# create materialized view mv_test_kenyon  as select * from test_kenyon where id > 10;
SELECT 10
postgres=# select * from mv_test_kenyon;
 id |       vname       
----+-------------------
 11 | kenyon good boy11
 12 | kenyon good boy12
 13 | kenyon good boy13
 14 | kenyon good boy14
 15 | kenyon good boy15
 16 | kenyon good boy16
 17 | kenyon good boy17
 18 | kenyon good boy18
 19 | kenyon good boy19
 20 | kenyon good boy20
(10 rows)
 
postgres=# \d+
                              List of relations
 Schema |      Name      |       Type        |  Owner   | Size  | Description 
--------+----------------+-------------------+----------+-------+-------------
 public | mv_test_kenyon | materialized view | postgres | 16 kB | 
 public | test_kenyon    | table             | postgres | 16 kB | 
(2 rows)
 
postgres=# \d mv_test_kenyon
Materialized view "public.mv_test_kenyon"
 Column |  Type   | Modifiers 
--------+---------+-----------
 id     | integer | 
 vname  | text    |
--size有大小(默认空表是8kb,而这里是16kb)说明存储了数据，有相应的物理文件，并且有类似表的结构
 
--表和物化视图的文件地址
postgres=# select oid,pg_relation_filepath(oid),relpages from pg_class where relname = 'test_kenyon';
  oid  | pg_relation_filepath | relpages 
-------+----------------------+----------
 16396 | base/12896/16428     |        0
(1 row)
 
postgres=# select oid,pg_relation_filepath(oid),relpages from pg_class where relname = 'mv_test_kenyon';
  oid  | pg_relation_filepath | relpages 
-------+----------------------+----------
 16459 | base/12896/16459     |        0
(1 row)
3.物化视图更新
postgres=# insert into test_kenyon values(21,'bad boy');
INSERT 0 1
postgres=# insert into test_kenyon values(22,'bad boy2');
INSERT 0 1
postgres=# select * from test_kenyon where id>20;
 id |  vname   
----+----------
 21 | bad boy
 22 | bad boy2
(2 rows)
 
postgres=# select * from mv_test_kenyon where id>20;
 id | vname 
----+-------
(0 rows)
--物化视图的数据没有刷新过来
 
--刷新物化视图数据
postgres=# refresh materialized view mv_test_kenyon;
REFRESH MATERIALIZED VIEW
postgres=# select * from mv_test_kenyon where id>20;
 id |  vname   
----+----------
 21 | bad boy
 22 | bad boy2
(2 rows)
 
--使用with no data刷新
postgres=# insert into test_kenyon values(32,'bad boy3'); 
INSERT 0 1
postgres=# select * from mv_test_kenyon where id>20;     
 id |  vname   
----+----------
 21 | bad boy
 22 | bad boy2
(2 rows)
 
postgres=# refresh materialized view mv_test_kenyon with no data;
REFRESH MATERIALIZED VIEW
postgres=# \d+
                                 List of relations
 Schema |      Name      |       Type        |  Owner   |    Size    | Description 
--------+----------------+-------------------+----------+------------+-------------
 public | mv_test_kenyon | materialized view | postgres | 8192 bytes | 
 public | test_kenyon    | table             | postgres | 16 kB      | 
(2 rows)
 
postgres=# select * from mv_test_kenyon;
ERROR:  materialized view "mv_test_kenyon" has not been populated
HINT:  Use the REFRESH MATERIALIZED VIEW command.
使用了with no data刷新后会导致物化视图里面的数据清除干净，并使物化视图不可用，如果需要继续使用，需要使用REFRESH MATERIALIZED VIEW