Connection to Oracle Parallel Server

[mzhu]

Based on the OPS document, OPS distributes the client connections across the cluster, that is, directs the client request to the least loaded node to process the database connection. My question is :

How to access the OPS connection? Do I need to specify one particular node to connect to? For example, if I use JDBC to make connection, I may use the code like:
Connection conn = DriverManager.getConnection("jdbcracle:thin@::", "user", "pass");
Which node should I use as :: ?

Thanks for any help.

[mzhu]

In the above post, :: should be [host]:[port]:[sid].

Sorry about that.

[buggy88]

On any client machine where you've the ORACLE client installed, there should be a tnsnames.ora file which has database connection set up.

There're several ways to set up entries in the tnsnames.ora

1) Usually, there's a host alias for all cluster nodes, e.g. alias OPSnode. In your tnsnames.ora file, the entry may look like this,

DBName=
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (COMMUNITY = tcp)(PROTOCOL = TCP)
(Host = OPSnode)(Port = 15xx))
)
(CONNECT_DATA = (SID = DBName))
)

In this way, you rely on the host's load balancing feature to decide which node to connect.

2) In some advance set up for 8.1.7 client, it's possible to use load balancing option, failover option and the entry could look like,

Dbname=
(DESCRIPTION =
(FAILOVER = ON)
(ADDRESS = (COMMUNITY = tcp)(PROTOCOL = TCP)
(Host = nodeA)(Port = 15xx))
(ADDRESS = (COMMUNITY = tcp)(PROTOCOL = TCP)
(Host = nodeB)(Port = 15xx))
(ADDRESS = (COMMUNITY = tcp)(PROTOCOL = TCP)
(Host = nodeC)(Port = 15xx))
(CONNECT_DATA = (SERVICE_NAME = Dbname)
(SERVER = DEDICATED))
)

3) There're some extra set up if you want to use ORACLE MTS to handle large no. of connections on the database side. If you need further information, these're documented in OPS adminstrator manual for specific database version.

In your application, you could just say connect user/pass@DbName.

Hope this helps.