Horizontally scaling a database

Hi all,

I am looking for ideas how to scale database horizontally as opposed to adding more CPUs, memory and disks on a single machine.

Here are the main requirements:

We need to store apporx 300 GB of data a month. It will be OLTP system. We want to use commodity hardware and open source database. we are willing to sacrifice performance for cost. E.g. a single row search from 2 billion rows table should be returned in 2 sec. Start with one server, when it reaches its capacity add one more server and so on.

Oracle RAC doesn't fit as it is single storage system. MySQL cluster database replicates data to all its cluster- we don't want to replicate the data.

I am trying to emulate google type file system with RDBMS capabilities something like a database farm where each database work independently. A query is submitted to all databases in the farm, matching data found and gathered at one place and returned as single output.

Any ideas?

Thanks

Sandeep

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