POSTGREsql9.1 版本支持了外表，今天进行一个简单的测试：
1. 导入外表插件：
pgdb1=# create extension file_fdw;
CREATE EXTENSION
create extension参见手册： http://www.postgresql.org/docs/9.1/static/sql-createextension.html
特别注意，在create extension要安装了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. 查看表属性
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 查询操作
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"
