W B Hacker wrote:
> Jeff Garzik wrote:
>
>> David Saez Padros wrote:
>>
>>> we use here a cdb database for white/black listing that is rebuilt every
>>> 5 minutes from a mysql database (with more than 4 million ip addresses),
>>> in our case the cdb read speed compensates the databse rebuild every 5
>>> minutes. Of course this maybe even better using some dbm like database
>>> but we don't have tried it yet. For other purposes where data is updated
>>> from time to time is even better (username/passwords, etc ...)
>>
>>
>> I agree cdb is a nice solution, but I would love to see a comparison
>> with SQlite.
>>
>> Replacing the cdb database every five minutes seems like it would
>> destroy the kernel's ability to cache data.
> Muhhh .... 'the kernel' isn't what caches the data used here... but
> never mind ...
Incorrect.
> No external client/process can safely make an assumption about the
> 'currency' of data drawn from a DB engine, be it SQLite, DB2 or even
> (especially) IMS.
Irrelevant.
> One must ask the 'engine'. Always.
Obvious.
> It is the very nature of such animals to be altering data elsewhere
> while your process is off having lunch.
Irrelevant.
> Special tools exist to alleviate that, most specifcally in Oracle, DB2,
> and similar 'industrial strength' DBMS designed/modified for
> distributed/remote clustering.
No need for special tools. Just sqlite and exim.
> As to timing - well 'five minutes' is an archaeological epoch for a CPU,
> or even a storage device.
Depends on machine configuration and workload.
> Caches are updated and flushed in timespans of pico, nano, micro or
> milli seconds, depending on how close they are to the silicon...
Not the kernel pagecache.
Jeff
