postgresql建立外表

POSTGRESQL9.1 版本支持了外表，今天進行一個簡單的測試：

1. 導入外表插件：

pgdb1=# create extension file_fdw;
CREATE EXTENSION

create extension參見手冊：http://www.postgresql.org/docs/9.1/static/sql-createextension.html

特別注意，在create extension要安裝了contrib下面程序

2. 建立文件server：

pgdb1=# create server file_server foreign data wrapper file_fdw;
CREATE SERVER

3.建立外表：

create foreign table text_table(PART_KEY                                                                   BIGINT,
pgdb1(#  USER_KEY                                                                  BIGINT,
 LOG_COUNT                                                                  BIGINT,
 ONLINE_DURATION                                                            BIGINT,
pgdb1(#  ONLINE_DAYS                                                                BIGINT,
pgdb1(#  FREQUENT_PERIOD                                                            BIGINT,
pgdb1(#  MSG_COUNT                                                                  BIGINT,
pgdb1(#  FRIENDS_COUNT                                                              BIGINT,
pgdb1(#  CONTACT_COUNT                                                              BIGINT,
pgdb1(#  RECENT_COUNTRY_ID                                                          BIGINT,
pgdb1(#  RECENT_PROVINCE_ID                                                         BIGINT,
pgdb1(#  RECENT_CITY_ID                                                             BIGINT,
pgdb1(#  RECENT_PLACE                                                               VARCHAR(1000)
pgdb1(# pgdb1(# pgdb1(#  ) server file_server OPTIONS(format 'text',filename '/data/vince/testdata/a.txt',delimiter ',',NULL '');

CREATE FOREIGN TABLE

4. 查看錶屬性

pgdb1=# \d+ text_table                  
                         Foreign table "public.text_table"
       Column       |          Type           | Modifiers | Storage  | Description 
--------------------+-------------------------+-----------+----------+-------------
 part_key           | bigint                  |           | plain    | 
 user_key           | bigint                  |           | plain    | 
 log_count          | bigint                  |           | plain    | 
 online_duration    | bigint                  |           | plain    | 
 online_days        | bigint                  |           | plain    | 
 frequent_period    | bigint                  |           | plain    | 
 msg_count          | bigint                  |           | plain    | 
 friends_count      | bigint                  |           | plain    | 
 contact_count      | bigint                  |           | plain    | 
 recent_country_id  | bigint                  |           | plain    | 
 recent_province_id | bigint                  |           | plain    | 
 recent_city_id     | bigint                  |           | plain    | 
 recent_place       | character varying(1000) |           | extended | 
Server: file_server
Has OIDs: no

5 查詢操作

pgdb1=# select count(*) from text_table; 
 count  
--------
 100000
(1 row)

6.delete,update操作

update text_table set log_count=0 where user_key=14154;
ERROR:  cannot change foreign table "text_table"

delete from text_table where user_key=14154；
ERROR:  cannot change foreign table "text_table"

看出外邊只能進行查詢操作不能修改