NoSQL

CAP Theorem

Good Article Explaining Eventual Consistency

 HBase

HBase Storage Architecture 

HBase vs BigTable 

HBase MapReduce Integration

HBase and HDFS Locality

HBase Coprocessors

HBase Real World Use Cases

Cassandra vs HBase

 Java

Java Interviews and Basic Concepts

Spring and Web Frameworks

Spark

Spark Gotchas

Spark Best Practices and Tuning Guide

Spark Memory Management

Tuning GC in Spark

Spark Secondary Sort

How to Implement MapReduce like Spark