I am currently trying to learn more about Amazon DocumentDB and I have a question I cannot see the answer to in the documentation. I know 1/3 of DocumentDB RAM is devoted to its own services, so it is the other 2/3 of RAM that DocumentDB devotes to storing indexes and data, but, out of these 2/3 of memory, what percentage is dedicated to indexes and what percentage is dedicated to data? Can anyone help me here?
There is no fixed percentage of RAM dedicated to indexes and data. Amount of memory dedicated to data versus index depends on your use case. You can use the IndexBufferCacheHitRatio metric and BufferCacheHitRatio metric to identify what percent of your indexes and workset are being serviced out of RAM