[mkjones]

I think when people say "relational doesn't scale," what they mean is "MySQL often requires application-level changes to scale out."

I assume (among this crowd, anyway) that scaling out is more desirable vs. scaling up because the majority of the hardware costs are variable, whereas scaling up requires a step function of large cash investments that startups often can't afford.

Do those massive systems on Oracle etc scale out, or simply scale up with expensive hardware?

[fendale]

You can certainly scale out with Oracle RAC. At some point the bottleneck will likely be disk however, so buying a high end storage system would probably become priority.

[jacques_chester]

> Do those massive systems on Oracle etc scale out, or simply scale up with expensive hardware?

Both. If you still need ACID guarantees and want hundreds of thousands (or even millions, if necessary) of TPM, you will need to pay the piper.