This book is a Gold mine on Apache Hadoop and covers extensively and in depth the following mentioned concepts with loads of illustrations and Examples:-
1.HDFS
2.Map Reduce
3.Pig
4.Hive
5.Sqoop
6.Flume
7.Eclipse Integrated Development Environment( IDE )
8.Differences between Old and New API
9.ToolRunner
10.JUnit and MRUnit
11.Distributed Cache
12.Common MapReduce Algorithms like Sorting , Searching , Indexing , Term Frequency and Word Co-Occurrence
13.Machine Learning
14.Term Frequency – Inverse Document Frequency ( TF-IDF )
15.Sequence Files
16.Avro
17.Reduce-Side Joins
18.Secondary Sort
19.Oozie

It covers lots of Practical Development Tips & Techniques like Debugging , logging , logging with log 4j.

Graphs are also covered in detail