Easysoft Blog

Mon, 24 Jul 2017

Connecting Oracle to PostgreSQL

The following instructions show you how to connect Oracle on Linux to PostgreSQL. For further information about DG4ODBC, refer to our DG4ODBC tutorial.

  1. Please contact the Easysoft Sales team () for the PostgreSQL ODBC driver.
  2. Install and license the PostgreSQL ODBC driver on the machine where Oracle is installed.

    For installation instructions, see the ODBC driver documentation.

    Note You need the unixODBC Driver Manager installed on your machine. The Easysoft distribution includes a version of the unixODBC Driver Manager that the Easysoft PostgreSQL ODBC driver has been tested with. The Easysoft driver setup program gives you the option to install unixODBC.

  3. Create an ODBC data source in /etc/odbc.ini that connects to the PostgreSQL database you want to access from Oracle. For example:
    [POSTGRES_SAMPLE]
    Driver=Easysoft ODBC-Postgres Server
    Description=Easysoft ODBC-Postgres Server
    Server=192.0.2.1
    Port=5432
    Database=employees
    User=postgres
    Password=p4550rd
    Logging=No
    LogFile=
    Encrypt=No
  4. Use isql to test the new data source. For example:
    cd /usr/local/easysoft/unixODBC/bin
    ./isql.sh -v POSTGRESQL_SAMPLE

    At the prompt, type "help" to display a list of tables. To exit, press return in an empty prompt line.

    If you are unable to connect, refer to this article for assistance.

  5. Create a DG4ODBC init file. To do this, change to the hs/admin subdirectory. For example:
    cd $ORACLE_HOME/product/11.2.0/xe/hs/admin

    Create a copy of the file initdg4odbc.ora. Name the new file initpostgresql.ora.

  6. Ensure these parameters and values are present in your init file:
    HS_FDS_CONNECT_INFO = my_postgresql_odbc_dsn

    Replace my_postgresql_odbc_dsn with the name of a PostgreSQL ODBC driver data source that connects to the target PostgreSQL server. For example

    HS_FDS_CONNECT_INFO = "POSTGRESQL_SAMPLE"
  7. Comment out the line that enables DG4ODBC tracing. For example:
    #HS_FDS_TRACE_LEVEL = <trace_level>
  8. Add an entry to listener.ora that creates a SID_NAME for DG4ODBC. For example:
    SID_LIST_LISTENER =
     (SID_LIST =
       (SID_DESC=
         (SID_NAME=postgresql)
         (ORACLE_HOME=$ORACLE_HOME)
         (PROGRAM=dg4odbc)
       )
     )
  9. Add a DG4ODBC entry to tnsnames.ora that specifies the SID_NAME created in the previous step. For example:
    POSTGRESQL =
      (DESCRIPTION =
        (ADDRESS = (PROTOCOL = TCP)(HOST = oracle_host)(PORT = 1521))
        (CONNECT_DATA =
          (SID = postgresql)
        )
        (HS = OK)
      )

    Replace oracle_host with the host name of your Oracle machine.

  10. Start (or restart) the Oracle Listener. For example:
    lsnrctl stop
    lsnrctl start
  11. Connect to your Oracle database in SQL*Plus.
  12. In SQL*Plus, create a database link for the target PostgreSQL server. For example:
    CREATE PUBLIC DATABASE LINK postgresqllink CONNECT TO
    "my_postgresql_user" IDENTIFIED by "my_postgresql_password" USING 'postgresql';
    SELECT * from employees@postgresqllink
Notes