Postgresql 提供了外键表的功能，sqlite_fdw唯一的遗憾是只能select，希望github上能够尽快更新吧！

下面我把sqlite_fdw 如何使用介绍下！

1、下载sqlite_fdw 软件包：

git clone https://github.com/gleu/sqlite_fdw 或者下载 .ZIP压缩文件

make

[postgres@mxl sqlite_fdw]$ make

gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -O2 -fpic -I. -I./ -I/usr/local/pgsql/include/server -I/usr/local/pgsql/include/internal -D_GNU_SOURCE -I/usr/include/libxml2   -c -o src/sqlite_fdw.o src/sqlite_fdw.c

gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -O2 -fpic -shared -o sqlite_fdw.so src/sqlite_fdw.o -L/usr/local/pgsql/lib -Wl,--as-needed -Wl,-rpath,'/usr/local/pgsql/lib',--enable-new-dtags  -lsqlite3 

make install 

[root@mxl sqlite_fdw]# make install

/bin/mkdir -p '/usr/local/pgsql/lib'

/bin/mkdir -p '/usr/local/pgsql/share/extension'

/bin/mkdir -p '/usr/local/pgsql/share/extension'

/bin/mkdir -p '/usr/local/pgsql/share/doc/extension'

/usr/bin/install -c -m 755  sqlite_fdw.so '/usr/local/pgsql/lib/sqlite_fdw.so'

/usr/bin/install -c -m 644 sqlite_fdw.control '/usr/local/pgsql/share/extension/'

/usr/bin/install -c -m 644 sql/sqlite_fdw--0.0.1.sql '/usr/local/pgsql/share/extension/'

/usr/bin/install -c -m 644 doc/sqlite_fdw.md '/usr/local/pgsql/share/doc/extension/'

2、在数据库引用sqlite_fdw

postgres=# CREATE EXTENSION sqlite_fdw;

CREATE EXTENSION

postgres=# \dx ;

                                     List of installed extensions

        Name        | Version |   Schema   |                        Description                        

--------------------+---------+------------+-----------------------------------------------------------

 pg_stat_statements | 1.2     | public     | track execution statistics of all SQL statements executed

 plpgsql            | 1.0     | pg_catalog | PL/pgSQL procedural language

 sqlite_fdw         | 0.0.1   | public     | SQLite Foreign Data Wrapper

 uuid-ossp          | 1.0     | public     | generate universally unique identifiers (UUIDs)

(4 rows)

3、创建一个fdw的server

CREATE SERVER sqlite_server  FOREIGN DATA WRAPPER sqlite_fdw  OPTIONS (database '/tmp/localdb.sqlite');

4、创建外键表

CREATE FOREIGN TABLE fdwuserrole(userid integer,roleid ingeter)  SERVER sqlite_server  OPTIONS (table 'userrole');

5、查看外键表server

postgres=# \des

             List of foreign servers

     Name      |  Owner   | Foreign-data wrapper 

---------------+----------+----------------------

 sqlite_server | postgres | sqlite_fdw

(1 row)

6、删除外键表

drop FOREIGN table fdwuserrole;

问题：1

src/sqlite_fdw.c:37:21: error: sqlite3.h: No such file or directory

make 的时候提示解析不了sqlite头文件

rpm -Uvh http://www6.atomicorp.com/channels/atomic/centos/6/x86_64/RPMS/atomic-release-1.0-21.el6.art.noarch.rpm 

yum update

yum sqlite-devel install -y

问题：2

安装sqlite_fdw的时候需要使用postgres 的pg_config 所以需要把postgres 的环境变量在root 添加一下