db-derby-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Peter Ondruška <peter.ondru...@yahoo.com>
Subject Re: When to shut down a database
Date Fri, 11 Apr 2014 05:40:49 GMT
Where did you read that?

If you declare your column to be CLOB(64K) than you have restricted its size. CLOB data type
 
 CLOB data type
A CLOB (character large object) value can be up to 2,147,483,647
characters long. A CLOB is used to store unicode character-based data, such
as large documents in any character set.   
View on db.apache.org Preview by Yahoo  
 
 
 String limitations
The following table lists limitations on string values in
Derby. Table 1. String limitations Value Maximum Limit Length of CHAR 254 characters Length
of VARCHAR 32,672 characters   
View on db.apache.org Preview by Yahoo  
 and String limitations



 
Peter
On Friday, 11 April 2014, 6:09, Chux <chux18@gmail.com> wrote:
 
Awesome insights guys, thanks for all your help.

BTW, I could not access the online documentation for some reason. Although I read somewhere
that 64k is the maximum size you can allocate a clob on embedded mode. Is this correct? I
would like to know what the limit is.



variable clob(64 K)

Thanks,
Chux



On Thu, Apr 10, 2014 at 5:32 AM, Dag H. Wanvik <dag.wanvik@oracle.com> wrote:


>On 09. april 2014 17:51, Rick Hillegas wrote:
>
>On 4/8/14 2:00 AM, Chux wrote:
>>
>>Hey Dag,
>>>
>>>Thanks for your insight.
>>>
>>>I'm using this as an embedded DB in a Java FX desktop application. This is a dumb
question but would you recommend shutting down the database ever after a transaction? Like
after you create a record then you shut it down after commit.
>>>
Depends on the application. If the database holds some kind of infrequently referenced metadata,
so that say, it is only queried or updated once a day, then you could consider an "on demand"
model where the database is booted for each query/update, then the query results are returned,
then the database is shut down so that it doesn't consume any resources. The big extra cost
of an "on demand" database would be this:  query/update time would be substantially longer
since every query/update involves booting the database, compiling the query/update, and gracefully
closing the database; that cost is on top of the steady-state cost of running a pre-compiled
query/update.
>>
>>
In such a scenario one might want to shut down the engine, too, not just the database.
>Note that shutting down the database will resources, but if the engine is still running,
one can further release resources by shutting that down as well.
>
>Cf. http://db.apache.org/derby/docs/10.10/devguide/tdevdvlp20349.html (engine shutdown)
>and http://db.apache.org/derby/docs/10.10/devguide/tdevdvlp40464.html (shutdown database)
>
>Thanks,
>Dag
>
>
>
>
>
>
>Hope this helps,
>>-Rick
>>
>>
>>>Best,
>>>Chux
>>>
>>>
>>>
>>>On Tue, Apr 8, 2014 at 12:32 AM, Dag H. Wanvik <dag.wanvik@oracle.com <mailto:dag.wanvik@oracle.com>>
wrote:
>>>
>>>
>>>    On 06. april 2014 21:02, George Toma wrote:
>>>
>>>    Hi Chux,
>>>>
>>>>    In my opinion  the example from  app.  referred at commit the
>>>>    transaction OR close the connection ( a connection could be
>>>>    transacted too ), and not to shutdown the db. If the business
>>>>    rule specifies that the db. needs to be shutdown when the app. is
>>>>    shutdown, then so be it.
>>>>
>>>>    Normally the db is not shutdown, not even when the app is down.
>>>>
>>>    This is true for a client/server application. For use with
>>>    embedded Derby, one would normally close down the database (and
>>>    the database engine) before exiting the application. If one
>>>    neglects to do so,
>>>    one would see longer start-up times as Dyre indicated.
>>>
>>>    Thanks,
>>>    Dag
>>>
>>>
>>>
>>>
>>>>    Cheers,
>>>>    George
>>>>    On Sunday, April 6, 2014 7:14 PM, Chux <chux18@gmail.com>
>>>>    <mailto:chux18@gmail.com> wrote:
>>>>    Hello guys,
>>>>
>>>>    I read in a sample app that you've got to shutdown a database. I
>>>>    was just confused if you need to shut it down on every connection
>>>>    transaction or just shut it down on application close, in my case
>>>>    a desktop applicaiton.
>>>>
>>>>    Best,
>>>>    Chux
>>>>
>>>>
>>>>
>>>
>>>
>>
>
Mime
View raw message