1,Download address
http://www.oracle.com/technetwork/database/database-technologies/instant-client/overview/index.html
2, Installation procedure
2.1 Create installation directory
[root@Postgres201 ~]# mkdir -p /u01/app/
[root@Postgres201 ~]# cd /u01/app/
2.2 Upload package and unzip
[root@Postgres201 app]# unzip instantclient-basic-linux.x64-11.2.0.4.0.zip 
[root@Postgres201 app]# unzip instantclient-sqlplus-linux.x64-11.2.0.4.0.zip 
[root@Postgres201 app]# unzip instantclient-sdk-linux.x64-11.2.0.4.0.zip 
[root@Postgres201 app]# mv instantclient_11_2/ oracle
[root@Postgres201 app]# cd oracle
2.3 Configure network files
[root@Postgres201 app]# cd oracle
[root@Postgres201 oracle]# mkdir -p network/admin
[root@Postgres201 oracle]# cd network/admin/
[root@Postgres201 admin]# vi tnsnames.ora
ora221 =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.221)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = orcl)
    )
  )
2.4 Configure user environment variables
export  ORACLE_HOME=/u01/app/oracle
export  TNS_ADMIN=$ORACLE_HOME/network/admin
export  LD_LIBRARY_PATH=$ORACLE_HOME:$LD_LIBRARY_PATH
export  PATH=$ORACLE_HOME:$PATH

1,Download address
http://pgxn.org/dist/oracle_fdw/
2,Installation procedure
[root@Postgres201 opt]# unzip oracle_fdw-2.0.0.zip
[root@Postgres201 opt]# cd oracle_fdw-2.0.0
#Execute after loading environment variables pg_config Is it corresponding to PGHOME/bin Directory. After compilation, it will be in the corresponding directory
[root@Postgres201 oracle_fdw-2.0.0]# source /home/postgres/.bashrc 
[root@Postgres201 oracle_fdw-2.0.0]# pg_config
[root@Postgres201 oracle_fdw-2.0.0]# make
[root@Postgres201 oracle_fdw-2.0.0]# make install
FAQ: implement make If present“/usr/bin/ld: cannot find -lclntsh"；The reason is that the library could not be found liblclntsh Documents;
//Solution:
1.    Check environment variables, see ORACLE Whether the relevant environment variables are set correctly
2.    Whether the file name is followed by oracle Version information; need to change name
//The file is in the oracle installation directory; in this case, you need to change the name
[root@Postgres201 oracle]# ln -sv libclntsh.so.11.1 libclntsh.so
[root@Postgres201 oracle_fdw-2.0.0]# make
[root@Postgres201 oracle_fdw-2.0.0]# make install
3,Create external extension
adsas=# create extension oracle_fdw;
ERROR:  could not load library "/app/pg12/lib/postgresql/oracle_fdw.so": libclntsh.so.11.1: cannot open shared object file: No such file or directory
//Solution:
1,create a file/etc/ld.so.conf.d/oracle.conf
2,Add content; libclntsh.so.11.1 The path of the file
/app/oracle
3,Perform load ldconfig
4,Log in again psql implement
adsas=# create extension oracle_fdw;
CREATE EXTENSION

CREATE FOREIGN TABLE fdw_game_pay_log (
ID int8 OPTIONS(key 'true'),
PAY_TIME timestamp NOT NULL,
APPID int2 NOT NULL,
QN varchar(20) NOT NULL,
ACCOUNTID varchar(64) NOT NULL,
AMOUNT decimal(6,2),
ORDER_NO text NOT NULL,
CP_ORDER_NO text
) server oradb OPTIONS (schema 'ADSAS', table 'TBL_GAME_PAY_LOG');

adsas=> insert into fdw_game_pay_log select * from tbl_game_pay_log;
ERROR:  error executing query: OCIStmtExecute failed to execute remote query
DETAIL:  ORA-08177: can't serialize access for this transaction

adsas=> begin;
BEGIN
adsas=> insert into fdw_game_pay_log select * from tbl_game_pay_log;
INSERT 0 1
adsas=> end;
COMMIT

CREATE OR REPLACE PROCEDURE "easou"."P_SYNC_TABLE_DATA" ()
    AS $BODY$
    /***********************************************************
     Copy the incremental TBL game pay log to FDW game pay log;
     Achieve PG-Oracle data incremental synchronization
     ***********************************************************/
DECLARE
    vn_old_id int8;
    vn_new_id int8;
BEGIN
    BGEIN
    -- Get last extracted id
    SELECT
        lid INTO vn_old_id
    FROM
        easou.tbl_sync_record
    WHERE
        tbl_name = 'tbl_game_pay_log';
    -- Intercept the maximum of this extraction id
    SELECT
        COALESCE(max(id), 0) INTO vn_new_id
    FROM
        easou.tbl_game_pay_log;
    -- Insert the extracted record into the external table
    INSERT INTO easou.fdw_game_pay_log (id, PAY_TIME, APPID, QN, ACCOUNTID, AMOUNT, ORDER_NO, CP_ORDER_NO)
    SELECT
        id,
        PAY_TIME,
        APPID,
        QN,
        ACCOUNTID,
        AMOUNT,
        ORDER_NO,
        CP_ORDER_NO
    FROM
        easou.tbl_game_pay_log
    WHERE
        id > vn_old_id;
    -- Update the extracted id
    UPDATE
        easou.tbl_sync_record
    SET
        lid = vn_new_id
    WHERE
        tbl_name = 'tbl_game_pay_log';
END;
EXCEPTION
    WHEN OTHERS THEN
        INSERT INTO tbl_error_log (error_time, error_desc, proc_name, deal_status)
            VALUES (now()::timestamp, SQLERRM, 'P_SYNC_TABLE_DATA', 0);
END;

$BODY$
LANGUAGE plpgsql