这篇文章主要介绍如何使用jdbc配置连接数据库(oracle的RAC配置的数据库)达到负载均衡的情况该例子是以个NODE的情况说明希望对大家有所帮助
我的问题是我需要设置oraclex的thin客户端连接到oracle的RAC环境上
注:这样连接可以通过RAC自动平衡负载
原文如下:
Hi Tom
I couldnt find this information easily on the net So Im submitting it here
and hope you make it available for anyone else looking for this information
My problem was I needed to configure the Oracle x thin driver (type IV) to
connect to an Oracle Real Application Cluster (RAC) environment
For example assuming you have a database called RAC_DB with two nodes node
and node
You would need to configure your tnsnamesora with the following information in
the following way:
RAC_DB =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = node)(PORT = ))
(ADDRESS = (PROTOCOL = TCP)(HOST = node)(PORT = ))
(LOAD_BALANCE = yes)
(FAILOVER = on)
)
(CONNECT_DATA =
(SERVICE_NAME = RAC_DB)
(FAILOVER_MODE = (TYPE = SELECT)
(METHOD = BASIC)
(RETRIES = )
(DELAY = )
)
)
)
Now if you start a SQL*PLUS session then you should see a connection on the
node instance If you start another SQL*PLUS session then Oracle should
connect you to the node instance (automatic load balancing) Its actually
pretty cool to see the first time
To pass this same information to the Oracles JDBC thin driver you essentially
concatenate a shorten version of the tnsnames information above and pass this to
the driver
String userid = scott;
String password = tiger;
String tnsnames_info =
(DESCRIPTION=(ADDRESS_LIST= +
(ADDRESS=(PROTOCOL=TCP)(HOST=node)(PORT=)) +
(ADDRESS=(PROTOCOL=TCP)(HOST=node)(PORT=)) +
(LOAD_BALANCE=yes)(FAILOVER=on)) +
(CONNECT_DATA=(SERVICE_NAME=rac_db))) ;
String url = jdbc:oracle:thin:@ + tnsnames_info;
DriverManagerregisterDriver(new oraclejdbcOracleDriver());
Connection dbConnection = DriverManagergetConnection(url userid password);
Thats it If your application creates multiple connection to the database
then you should see these connections load balance across the two instances
One last note Oracle only supports connection to a RAC configuration with the
i drivers so you should try to get the latest Oracle JDBC thin driver
HTH
Peter
and we said
you made it really hard you just needed the service! the load balancing and
all could be/should be setup on the listener side!
you have one listener both databases register with it as a service
that would be another option
Reviews
I think we tried that and it didnt work September
Reviewer: Peter Tran from Houston TX USA
Hi Tom
Im pretty sure we tried that but it didnt work with the thin driver That
approach will work if you use the OCI driver but not with the thin driver
Please send me an example of what you mean or what files I should configure to
test it out
Im always opened to easier options
Thanks
Peter
Followup:
you need to set up mts and a single listener thats it
pmon on each of the rac instances will tell the listener about the load and away
it goes you might not see the round robin right off (both are not yet
loaded) so itll be an unbalanced load balance initially but as the system
ramps itll balance out
Unknown territory September
Reviewer: Peter Tran from Houston TX USA
Im sorry but I really lost you with that last recommendation Rather than
frustrate you with my ignorance can you recommend the Oracle documentation that
I should read to brush up on this information?
Ill read this first and come back with questions if Im still lost
For example I dont understand why you want me to setup the database as MTS
Why cant I use dedicated server mode?
Thanks for the quick response
Peter
Followup:
in order for a single listener to service many instances on different
machines the listener must be servicing shared server connections the
listener cannot fork/exec a dedicated server since the listener may well not
be running on the machine the instance is on it needs to know dispatcher
addresses to redirect the client request to
htm
it is just inherit in the architecture
