Database Clusters

[Hari Mohan]

Hi guys,

I wonder how google and amazon keeps the Zetabytes of data always alive , i mean ., they dont load data from harddisk every time.., they load it from RAM.

for any J2ee based application , we use a DB (say Oracle DB) to store.

but typically we use a single user account to access the Oracle DB and store all our data in that schema/user.

for eg,

If google stores all gmail account in a single very large table or multiple tables., wont it be awkward to fetch data efficiently or effectively ?

Can we have database instance for a single or group of 10 people in  a VM ??

by this way , if there are a 100 millions users in gmail ., we would require 10 millions of database instances.

And If we could increase its capacity to 20 people , we would require just 5 millions of database instances.

hope this post doesnot turn out to be a silly or ackward question !!!!!

-Hari Mohan