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
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