Ask HN: Where can I find theoretic background on analytics reporting?

There are many questions when facing the decision of how to create your data scheme for events, whether you're using Elastic Search, Google's Big Query, Amazon's Redshift, Splunk and others. For example: 1.Metrics vs Dimensions - what is truly the difference between those definitions? 2.Should all my data be in a single flat event and have multiple values or should each event have only 1 value or maybe a mix of those approaches?