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From Daniel John Debrunner <...@debrunners.com>
Subject Re: SQL exception on shutdown
Date Mon, 20 Sep 2004 16:05:43 GMT
Joel Rosi-Schwartz wrote:


> It seems that shutting down a database always throws an exception, whether or 
> not the shutdown was successful. On success the ERROR code embedded in the 
> exception message is "ERROR 08006: Database 'DBNAME' shutdown." This makes it 
> difficult, if not impossible, to robustly check if the shutdown was 
> successful or not. Yes, a string compare could be done to the beginning of 
> the message, but this is fragile if the error message changes.

A string compare should be made on the SQL state
(SQLException.getSQLState()), not the text of the message, as the
message changes with locale. A change in the SQL state would be a change
of API and therefore should not occur without thought.

> What is the 
> value of the exception on success? I think this should changed, if for no 
> other reason then throwing an exception on success is really against best 
> practises and an anti-pattern to be avoided.

The issue is that standard JDBC getConnection() method calls (either
DriverManager or DataSource) are used to push the shutdown request to
Derby. A successful return from these methods would require a Connection
object to be returned. It seemed strange to return a connection object
to a database or system that was no longer active, what state would the
Connection be in, closed? So the decision was made to throw an
exception, which I think matches spirit of the JDBC spec. (Null as a
return is not supported by the spec).

The use of the standard JDBC mechanisms to push the shutdown request
means that the request can be passed to Derby by any networked JDBC
driver (e.g. DB2 universal driver, RmiJDBC, Weblogic's old Tengah
driver) as well as embedded.

Any alternate solutions are welcome!

Dan.

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