So I tried mongoDB, but the math didn’t add up. I’m now doing the math for using AWS’s SimpleDB for website analytics.

Some SimpleDB Limits

from the dev guide

• 256 attribute name-value pairs per item
• 1 MB request size
• 1 billion attributes per domain
• 10 GB of total user data storage per domain
• 25 item limit per BatchPutAttributes operation

Some baseline numbers to work with

• One of my sites has about 10k sessions per day with an average of 2 page views per session.
• Use a single SimpleDB domain, one item per page view (or ajax call)
• Keep session meta-data in the “entry page” item, i.e. the first one of the session.
• Session meta data is about 25 attributes
• A page view that isn’t a session has up to 10 attributes

Math on Attributes Constraint

1 billion attributes / (10,000 sessions/day * 25 attributes) + (10,000 secondary page views/day * 10 attributes) = 2900 days = 8 years of data based on the attributes constraint

Now with this project, I’m only up to 1600 sessions per day, but I expect the growth to continue FAR beyond 10k per day.