Comments on: Load balancing across MySQL servers using JDBC

By: MySQL Master/Slave Load Balancing with JPA and Spring — Dragisa Krsmanovic

MySQL Master/Slave Load Balancing with JPA and Spring — Dragisa Krsmanovic — Mon, 13 Jun 2011 20:25:15 +0000

[...] Load balancing across MySQL servers using JDBC by Todd Huss [...]

By: Todd Huss

Todd Huss — Tue, 08 Mar 2011 05:05:17 +0000

Mike, I’m no longer at the company where we implemented that but at the time we ended up defaulting everything to readonly. Then if a controller action needed to do something that might involte a write it called a method to switch the hibernate session to use a connection with the master db.

However, nowadays I would probably just write a spring interceptor such that if the controller action were annotated with @ReadWrite I would call setReadOnly(false).

By: Mike

Mike — Tue, 08 Mar 2011 01:10:44 +0000

Hi Todd,

Do you happen to have example code for that interceptor? You’re right, Spring no longer calls setReadOnly on the JDBC connection. The spring docs say that one can add custom advice to the transaction manager, but I can’t seem to find a working example anywhere.

By: Todd Huss

Todd Huss — Sun, 13 Aug 2006 20:19:46 +0000

Hi Andy, last time I checked the Spring source code, they had changed it so that it doesn’t call conn.setReadOnly so I do it myself in my own Spring interceptor. The best way to be sure is to try it yourself with some real code though and see.

By: Andy

Andy — Sun, 06 Aug 2006 12:58:23 +0000

hi,
i am using the Spring transaction framework. this should set readOnly(true) automatically?

i am right ?

By: Todd Huss

Todd Huss — Wed, 31 May 2006 16:00:38 +0000

Hibernate will not do it for you so the latter is what you need to do, however, I would abstract all of the transaction management and setting readonly of the connection out as an interceptor.

By: Jack Gorden

Jack Gorden — Wed, 31 May 2006 12:47:45 +0000

One question regarding Hibernate … does it do the required con.setReadOnly calls behind the scenes or did you use the raw connection?

@@ Read/Write @@

factory.getCurrentSession().beginTransaction();

// Do some work
factory.getCurrentSession().save(…);

factory.getCurrentSession().getTransaction().commit();

Or:

boolean readOnly = factory.getCurrentSession().connection().getReadOnly();
factory.getCurrentSession().connection().setReadOnly(false);
factory.getCurrentSession().beginTransaction();

// Do some work
factory.getCurrentSession().save(…);

factory.getCurrentSession().getTransaction().commit();
factory.getCurrentSession().connection().setReadOnly(readOnly);

@@ Read-Only @@

factory.getCurrentSession().beginTransaction();

// Do some work

factory.getCurrentSession().getTransaction().commit();

Or:

boolean readOnly = factory.getCurrentSession().connection().getReadOnly();
factory.getCurrentSession().connection().setReadOnly(true);
factory.getCurrentSession().beginTransaction();

// Do some work

factory.getCurrentSession().getTransaction().commit();
factory.getCurrentSession().connection().setReadOnly(readOnly);

By: Mathias Bogaert

Mathias Bogaert — Thu, 02 Feb 2006 10:17:57 +0000

Exactly what I needed. Didn’t know this was possible, thanks!

By: Mark Matthews

Mark Matthews — Wed, 01 Feb 2006 17:33:46 +0000

Todd,

Let me know how it goes, and if you find any issues that need to be addressed! I’m always glad to see folks try this kind functionality, as I think it’s one of the value-add’s MySQL’s JDBC driver brings.