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From Sven Boden <list...@pandora.be>
Subject Re: cacheModel - Database Down and external app flush
Date Wed, 19 Apr 2006 21:48:24 GMT

For 1):
do you have the full nested stacktrace? Did you deactivate the ping 
query? and are you sure the exception originates in iBATIS (we'll see 
from the full stacktrace). The intention of a cache is to speed things 
up, it's not the intention to have a complete in-core database.

For 2)
There's no way for iBATIS to be automatically aware of updates by other 
applications. This is a problem for every database application, not just 
iBATIS. If you would develop an application without iBATIS (with your 
own developed caching), how would you know in your application whether 
another application updated your database?

Regards,
Sven

James Johnson wrote:

>I have a few questions regarding iBatis cacheModel. All help is greatly appreciated.
>
>1) When the iBatis cacheModel is used, a connection to the database server appears to
be still required. The data has been cached, so I'm not sure why the database server needs
to be up after caching the data. 
>
>For exapmle, I have test code that basically returns the same row of data n times. As
expected, the data is cached and remains unchanged desipte making updates using the database
command line client (i.e. outside of my program). During the ith (1<i<=n) try, I shutdown
the database server. I would expect iBatis to just use the cache results and not require the
database server to be up. However, instead I get the following error when I bring the database
server down: 
>
>Exception in thread "main" org.springframework.jdbc.CannotGetJdbcConnectionException:
Could not get JDBC Connection; nested exception is com.mysql.jdbc.CommunicationsException:
Communications link failure due to underlying exception: 
>
>** BEGIN NESTED EXCEPTION ** 
>
>java.net.SocketException
>
>MESSAGE: java.net.ConnectException: Connection refused: connect
>
>
>I would like to have mechanism that allows the application to use cached data in the event
the database server is down as it does when the database server is up. Is the cachModel capable
of providing this functionality? Why does the database server need to be up when iBatis is
using cached results?
>
>2) By specifying the flushOnExecute, iBatis will flush the cache when a certian statement(s)
is executed. Is there a way for iBatis to flush the cache when anything (i.e. another application)
makes an update, insert or delete?
>
>  
>


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