oracle_fdw概述

oracle_fdw 是一种postgresql外部表插件，可以读取到Oracle上面的数据。是一种非常方便且常见的pg与Oracle的同步数据的方法

配置Oracle环境

Oracle_fdw 的编译依赖系统中需要有pg_config和Oracle的环境

1.下载instant oracle client

从oralce官网下载 ‘Basic’ and ‘SDK’
下载网址：https://www.oracle.com/database/technologies/instant-client/linux-x86-64-downloads.html

下载如下两个压缩包：

instantclient-basic-linux.x64-11.2.0.4.0.zip

instantclient-sdk-linux.x64-11.2.0.4.0.zip

oracle_fdw依赖上述两个包，包里面的内容可以在oracle下载页查看，如下

Instant Client Package - Basic: All files required to run OCI, OCCI, and JDBC-OCI applications

Instant Client Package - SDK: Additional header files and an example makefile for developing Oracle applications with Instant Client

oracle_fdw下载地址 [https://pgxn.org/dist/oracle_fdw/](# https://pgxn.org/dist/oracle_fdw/)

oracle_fdw官方（https://github.com/laurenz/oracle_fdw#5-installation-requirements）介绍里面有以下对依赖包的描述：

You need to install Oracle’s C header files as well (SDK package for Instant Client). If you use the Instant Client ZIP files provided by Oracle, you will have to create a symbolic link from libclntsh.so to the actual shared library file yourself.

从官网下载 instantclient-basic-linux.x64-12.2.0.1.0.zip、 instantclient-sdk-linux.x64-12.2.0.1.0.zip、 instantclient-sqlplus-linux.x64-12.2.0.1.0.zip三个文件包，并放到/opt/oracle/目录下

mv instantclient-basic-linux.x64-12.2.0.1.0.zip instantclient-sdk-linux.x64-12.2.0.1.0.zip instantclient-sqlplus-linux.x64-12.2.0.1.0.zip  /opt/oracle/

2.安装instant oracle client

# mkdir /usr/local/oracle
# unzip -d /usr/local/oracle instantclient-basic-linux.x64-11.2.0.4.0.zip
# unzip -d /usr/local/oracle instantclient-sdk-linux.x64-11.2.0.4.0.zip

解压三个文件包
unzip instantclient-basic-linux.x64-12.2.0.1.0.zip
unzip instantclient-sdk-linux.x64-12.2.0.1.0.zip
unzip instantclient-sqlplus-linux.x64-12.2.0.1.0.zip

解压后会生成instantclient_12_2 目录，将其更名为instantclient
mv instantclient_12_2 instantclient

3.下载并上传oracle_fdw

下载网址：https://github.com/laurenz/oracle_fdw/releases

4.配置环境变量（主要是动态链接库）

在root和postgres下最好都配置好这个环境
export ORACLE_HOME=/opt/oracle/instantclient
export OCI_LIB_DIR=$ORACLE_HOME
export OCI_INC_DIR=$ORACLE_HOME/sdk/include
export LD_LIBRARY_PATH=$ORACLE_HOME:$LD_LIBRARY_PATH

make
[root@pg01 oracle_fdw-2.0.0]# make
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC -I/sdk/include -I/oci/include -I/rdbms/public -I/usr/include/oracle/12.2/client -I/usr/include/oracle/12.2/client64 -I/usr/include/oracle/12.1/client -I/usr/include/oracle/12.1/client64 -I/usr/include/oracle/11.2/client -I/usr/include/oracle/11.2/client64 -I/usr/include/oracle/11.1/client -I/usr/include/oracle/11.1/client64 -I/usr/include/oracle/10.2.0.5/client -I/usr/include/oracle/10.2.0.5/client64 -I/usr/include/oracle/10.2.0.4/client -I/usr/include/oracle/10.2.0.4/client64 -I/usr/include/oracle/10.2.0.3/client -I/usr/include/oracle/10.2.0.3/client64 -I. -I./ -I/usr/pgsql-9.6/include/server -I/usr/pgsql-9.6/include/internal -D_GNU_SOURCE -I/usr/include/libxml2  -I/usr/include  -c -o oracle_fdw.o oracle_fdw.c
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC -I/sdk/include -I/oci/include -I/rdbms/public -I/usr/include/oracle/12.2/client -I/usr/include/oracle/12.2/client64 -I/usr/include/oracle/12.1/client -I/usr/include/oracle/12.1/client64 -I/usr/include/oracle/11.2/client -I/usr/include/oracle/11.2/client64 -I/usr/include/oracle/11.1/client -I/usr/include/oracle/11.1/client64 -I/usr/include/oracle/10.2.0.5/client -I/usr/include/oracle/10.2.0.5/client64 -I/usr/include/oracle/10.2.0.4/client -I/usr/include/oracle/10.2.0.4/client64 -I/usr/include/oracle/10.2.0.3/client -I/usr/include/oracle/10.2.0.3/client64 -I. -I./ -I/usr/pgsql-9.6/include/server -I/usr/pgsql-9.6/include/internal -D_GNU_SOURCE -I/usr/include/libxml2  -I/usr/include  -c -o oracle_utils.o oracle_utils.c
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC -I/sdk/include -I/oci/include -I/rdbms/public -I/usr/include/oracle/12.2/client -I/usr/include/oracle/12.2/client64 -I/usr/include/oracle/12.1/client -I/usr/include/oracle/12.1/client64 -I/usr/include/oracle/11.2/client -I/usr/include/oracle/11.2/client64 -I/usr/include/oracle/11.1/client -I/usr/include/oracle/11.1/client64 -I/usr/include/oracle/10.2.0.5/client -I/usr/include/oracle/10.2.0.5/client64 -I/usr/include/oracle/10.2.0.4/client -I/usr/include/oracle/10.2.0.4/client64 -I/usr/include/oracle/10.2.0.3/client -I/usr/include/oracle/10.2.0.3/client64 -I. -I./ -I/usr/pgsql-9.6/include/server -I/usr/pgsql-9.6/include/internal -D_GNU_SOURCE -I/usr/include/libxml2  -I/usr/include  -c -o oracle_gis.o oracle_gis.c
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC -shared -o oracle_fdw.so oracle_fdw.o oracle_utils.o oracle_gis.o -L/usr/pgsql-9.6/lib -Wl,--as-needed  -L/usr/lib64 -Wl,--as-needed -Wl,-rpath,'/usr/pgsql-9.6/lib',--enable-new-dtags  -L -L/bin -L/lib -lclntsh -L/usr/lib/oracle/12.2/client/lib -L/usr/lib/oracle/12.2/client64/lib -L/usr/lib/oracle/12.1/client/lib -L/usr/lib/oracle/12.1/client64/lib -L/usr/lib/oracle/11.2/client/lib -L/usr/lib/oracle/11.2/client64/lib -L/usr/lib/oracle/11.1/client/lib -L/usr/lib/oracle/11.1/client64/lib -L/usr/lib/oracle/10.2.0.5/client/lib -L/usr/lib/oracle/10.2.0.5/client64/lib -L/usr/lib/oracle/10.2.0.4/client/lib -L/usr/lib/oracle/10.2.0.4/client64/lib -L/usr/lib/oracle/10.2.0.3/client/lib -L/usr/lib/oracle/10.2.0.3/client64/lib 
make install
[root@pg01 oracle_fdw-2.0.0]# make install
/usr/bin/mkdir -p '/usr/pgsql-9.6/lib'
/usr/bin/mkdir -p '/usr/pgsql-9.6/share/extension'
/usr/bin/mkdir -p '/usr/pgsql-9.6/share/extension'
/usr/bin/mkdir -p '/usr/pgsql-9.6/doc/extension'
/usr/bin/install -c -m 755  oracle_fdw.so '/usr/pgsql-9.6/lib/oracle_fdw.so'
/usr/bin/install -c -m 644 .//oracle_fdw.control '/usr/pgsql-9.6/share/extension/'
/usr/bin/install -c -m 644 .//oracle_fdw--1.1.sql .//oracle_fdw--1.0--1.1.sql  '/usr/pgsql-9.6/share/extension/'
/usr/bin/install -c -m 644 .//README.oracle_fdw '/usr/pgsql-9.6/doc/extension/'

 export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/pgsql/lib:/usr/local/oracle/instantclient_11_2
 export PATH=$PATH:/usr/local/pgsql/bin
 export ORACLE_HOME=/usr/local/oracle/instantclient_11_2
 cd /usr/local/oracle/instantclient_11_2
 oracle_fdw找的是libclntsh.so,因此要加一个软连接去掉版本号
 ln -s libclntsh.so.11.1 libclntsh.so
 unzip oracle_fdw-ORACLE_FDW_2_1_0.zip
 cd oracle_fdw-ORACLE_FDW_2_1_0
 make
 make install

注意：这些环境变量是临时的，安装oracle_fdw使用

在后面pg中创建插件的时候，还是会报找不到动态连接库（虽然我配置了postgres用户的LD_LIBRARY_PATH环境变量），后面通过修改ld.conf解决（详见第五步），因此这里的LD_LIBRARY_PATH环境变量配置可以直接使用后面的ld.conf解决，但为显示整个过程，这里暂时使用临时变量

5.进入数据库安装插件

# su - postgres
# psql
postgres=#  create extension oracle_fdw;

执行会报错：ERROR: could not load library “/usr/local/pgsql-10.6/lib/oracle_fdw.so”: libclntsh.so.11.1: cannot open shared object file: No such file or directory

通过以下步骤解决：

# cd /etc/ld.so.conf.d/
# vi oracle-x86_64.conf
-------------------------------------
/usr/local/oracle/instantclient_11_2
-------------------------------------
# ldconfig

将oracle的库加入动态链接库，再次添加扩展即可

6.创建tnsnames.ora

 cd /usr/local/oracle/instantclient_11_2/
 mkdir -p network/admin/

创建一个或者复制一个tnsnames.ora过来，配置TNS

7.外部表使用

创建外部服务器

create server oracle_test foreign data wrapper oracle_fdw options(dbserver 'db');

oracle_test为外部服务器的名称，db为上一步tnsnames.ora中配置的tns

授权

grant usage on foreign server oracle_test to postgres;

本步不是必须的，如果要给非外部服务器的创建者使用，可以赋权

创建mapping

create user mapping for postgres server oracle_test options (user 'oracle', password 'oracle');

进入oracle数据库的凭证

创建外部表

create foreign table
    test_fdw( id int,
    name varchar(10) ) server oracle_test options (schema 'USER01',table 'TEST01');

schema和table必须为大写，否则无法使用

查看外部服务的信息

select oracle_diag();
select * from test_fdw;
 

其他

创建外部数据源服务

postgres=# CREATE SERVER oradb FOREIGN DATA WRAPPER oracle_fdw OPTIONS (dbserver '//192.168.56.8:1521/orcl');

建用户映射，指定连接远程数据库的用户名和密码，命令如下：

postgres=# CREATE USER MAPPING FOR postgres SERVER osdba_fdw OPTIONS (user 'test', password 'cstech');
CREATE USER MAPPING

没有报错的情况下说明已经建好了，可以创建外部表进行测试了，注意：外部表的字段必须包含在数据源数据的字段内，可以一一对应，也可以只使用其中某些字段，但是不能指定数据源没有的字段，并且每个字段的数据类型要一一对应，否则创建外部表会失败。

postgres=# CREATE  FOREIGN TABLE "test_tab" (id int,name text SERVER osdba_fdw OPTIONS (table 'TEST_TAB');
CREATE FOREIGN TABLE
查看表的结构

postgres=# \d test_tab 
                 Foreign table "public.test_tab"
 Column |  Type   | Collation | Nullable | Default | FDW options 
--------+---------+-----------+----------+---------+-------------
 id     | integer |           |          |         | 
 name   | text    |           |          |         | 
Server: osdba_fdw
FDW options: ("table" 'TEST_TAB')
查看数据

postgres=# select * from test_tab ;