Re: DB mirroring support with JDBC?
- From: Joe Weinstein <joeNOSPAM@xxxxxxx>
- Date: Tue, 14 Feb 2006 11:55:06 -0800
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/plsql/ml2_documents.showDocument?p_database_id=NOT&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
""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
.
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- From: "Shelby Goerlitz [MSFT]"
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