Database parallelism choices greatly impact scalability

Sam Madden in the The Database Column blog covers some database architectures. Quick summary:

Shared-memory systems don't scale well as the shared bus becomes the bottleneck

Shared-disk systems don't scale well either

Shared-nothing scales the best

Comments

[Greg Wilson]

Praise for shared-nothing is only meaningful if there's also discussion of the cost. Is it harder to build and debug, and if so, how much? What's the comparative cost of coding errors that survive into production deployments? If the answers are "no" and "the same", then it's a clear win, but I doubt they are.

[Todd Hoff]

> Praise for shared-nothing is only meaningful if there's also discussion of the cost.

Good point. Shared nothing isn't easy, but I've found the setup and maintenance of the other architectures pretty hard as well. Maybe that's just me though.