Saturday, September 28, 2013

Create Database Link to DB on Amazon EC2 Instance

From a database, we can create a database link to another remote database such as one on Amazon EC2 virtual server as shown below. Here ec2-12-34-567-899.compute-1.amazonaws.com is the amazon EC2 Linux instance's Public DNS.

SQL> create database link dl_aws_ec2 connect to prod_DB identified by PWDXXX using '(description=(address=(protocol= TCP)(host=ec2-12-34-567-899.compute-1.amazonaws.com)(port=1521)) (connect_data=(sid=XE)))';
Database link created.

SQL> select count(1) from user_tables@dl_aws_ec2;

COUNT(1)
15

Just like we query any databases, we can see a few tables with names starting with the word "DEMO", count the number of records, and if we want, make a local copy of the tables.

SQL> select table_name from user_tables@dl_aws_ec2 where table_name like 'DEMO%' and rownum <5 order by table_name;

TABLE_NAME
DEMO_CUSTOMERS
DEMO_ORDERS
DEMO_ORDER_ITEMS
DEMO_PAGE_HIERARCHY

SQL> select count(*) from DEMO_CUSTOMERS@dl_aws_ec2;

COUNT(*)
7

SQL> create table DEMO_CUSTOMERS_LOCAL as select * from DEMO_CUSTOMERS@dl_aws_ec2;
Table created.

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