SQL Server JDBC - DB mirroring support with JDBC?

Author

DB mirroring support with JDBC?

Adam Fletcher

2006-02-09, 8:23 pm

Hi All,

Does the new MS JDBC driver support the database mirroring features of SQL
2k5? Is there a way to specify the failover server to the JDBC driver? And to
have the JDBC driver handle the failover and failback?

Thanks, Adam

Shelby Goerlitz [MSFT]

2006-02-14, 1:23 pm

Adam:

SQL Server 2005 SP1 will have an updated failover story and we plan to have
client support for failover when we ship the v1.1 version of the 2005 JDBC
driver, scheduled for June.

-shelby

Shelby Goerlitz
Microsoft SQL Server Data Programmability

Adam Fletcher

2006-02-14, 8:23 pm

Thanks for the reply!

Right now we're making a decision about our failover options and 2k5's
mirroring is important to us. Will the SP1 story include having the mirror
appear as single instance to the client? That would be ideal, as then the
client doesn't have to change to support mirroring.

We've been waiting for the SQL 2k5 mirroring in SE because Enterprise
Edition is simply too expensive for doing active/passive mirroring that
appears as one instance. I'm hopeing mirroring does what want - it's cheaper
for us to validate on RAC then pay for EE as we can get clustering with 10g
RAC for a fraction of the cost per processor.

""Shelby Goerlitz [MSFT]"" wrote:

> Adam:
>
> SQL Server 2005 SP1 will have an updated failover story and we plan to have
> client support for failover when we ship the v1.1 version of the 2005 JDBC
> driver, scheduled for June.
>
> -shelby
>
> Shelby Goerlitz
> Microsoft SQL Server Data Programmability
>
>

Joe Weinstein

2006-02-14, 8:23 pm

Adam Fletcher wrote:

> Thanks for the reply!
>
> Right now we're making a decision about our failover options and 2k5's
> mirroring is important to us. Will the SP1 story include having the mirror
> appear as single instance to the client? That would be ideal, as then the
> client doesn't have to change to support mirroring.
>
> We've been waiting for the SQL 2k5 mirroring in SE because Enterprise
> Edition is simply too expensive for doing active/passive mirroring that
> appears as one instance. I'm hopeing mirroring does what want - it's cheaper
> for us to validate on RAC then pay for EE as we can get clustering with 10g
> RAC for a fraction of the cost per processor.

Hi Adam, beware of JDBC and DBMS failover. Especially don't trust Oracle's
TAF. Failover will have to be at the driver level, so your application
has to close a dead connection and get a new one (which presumably is to
the backup DBMS). This is because *no* DBMS failover architecture will
be able to maintain all the transactional, computational, and session
state of a running JDBC connection after a failover. For example, any
cursors that are underlying any cached PreparedStatements or running
ResultSets may be defunct, so even if the connection failed over, all
your statements would need to be reconstructed etc. If you involve
yourself in XA transactions it becomes even more complicated. Here is
a link to Oracle docs describing the ways a TAF failed-over connection
would be worse than useless:

(http://metalink.oracle.com/metalink...OT&p_id=97926.1)

I have no fish to fry here, I just work with lots of customers wanting
JDBC and HA DBMS architecture, so I want their expectations to be
educated...
Joe Weinstein at BEA Systems

[color=darkred]
> ""Shelby Goerlitz [MSFT]"" wrote:
>
>

Adam Fletcher

2006-02-14, 8:23 pm

Thanks for the information Joe. I'm all about the right solution for the
application, so it looks like my developers may need to get involved either
way.

"Joe Weinstein" wrote:

>
>
> Adam Fletcher wrote:
>
>
> Hi Adam, beware of JDBC and DBMS failover. Especially don't trust Oracle's
> TAF. Failover will have to be at the driver level, so your application
> has to close a dead connection and get a new one (which presumably is to
> the backup DBMS). This is because *no* DBMS failover architecture will
> be able to maintain all the transactional, computational, and session
> state of a running JDBC connection after a failover. For example, any
> cursors that are underlying any cached PreparedStatements or running
> ResultSets may be defunct, so even if the connection failed over, all
> your statements would need to be reconstructed etc. If you involve
> yourself in XA transactions it becomes even more complicated. Here is
> a link to Oracle docs describing the ways a TAF failed-over connection
> would be worse than useless:
>
> (http://metalink.oracle.com/metalink...OT&p_id=97926.1)
>
> I have no fish to fry here, I just work with lots of customers wanting
> JDBC and HA DBMS architecture, so I want their expectations to be
> educated...
> Joe Weinstein at BEA Systems
>
>
>
>

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