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Re: implementing asynchronous notifications PLEASE CONFIRM MY

From: "Arcadius A(dot)" <arcadius(at)menelic(dot)com>
To: David Gagnon <dgagnon(at)siunik(dot)com>
Cc: pgsql-jdbc(at)postgresql(dot)org
Subject: Re: implementing asynchronous notifications PLEASE CONFIRM MY
Date: 2005-08-29 03:34:02
Message-ID: 4312822A.8030007@menelic.com (view raw or flat)
Thread:
Lists: pgsql-jdbc
David Gagnon wrote:

> Hi ,
>
>   Thanks for your answer, see my answer below..
>
>> David Gagnon wrote:
>>
>>> Hi all,
>>
[...]

>>
>> However I do not know your exact requirement, if I were to solve such 
>> a problem, I would not try to put any overhead on the DB server; 
>> after all, the purpose of caching is to give a brake to the DBServer.
>>
>> In fact, the easiest way to have the cache in sync with the DB is to 
>> have a kind of Facade , a unique class, with static methods for 
>> reading/writing data for both the cache and the DB.
>>
>> Using a single class for reading/writing , you won't need the DB to 
>> notify  you of changes since all call go through your facade, that 
>> means that you know when things are being changed and can take action.
>>
>> However, your requirements my be different.
>>
>>
>> Regards. \
>
>
[...]

> The big problem is that when a user launch a stored procedure.. chance 
> are that he will consult the other data right after the completion of 
> the stored procedure.  If data have not been updated in the cache I 
> will display invalid data :-(
>
If the user is calling the SP from the same Java app , then , what I 
said before is still valid.
The method which calls the SP should clear/invalidate the cache .
So, the next time the user tries to view data, as the cache is 
empty/invalidated , new stuff should be loaded from the DB.


Regards.

Arcadius.

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