Index: src/docbkx/book.xml
===================================================================
--- src/docbkx/book.xml (revision 1234667)
+++ src/docbkx/book.xml (working copy)
@@ -522,6 +522,19 @@
+ Joins
+ Whether HBase supports joins is a common question on the dist-list, and there is a simple answer: it doesn't,
+ at not least in the way that RDBMS' support them (e.g., with equi-joins or outer-joins in SQL). As has been illustrated
+ in this chapter, the read data model operations in HBase are Get and Scan.
+
+ However, that doesn't mean that equivalent join functionality can't be supported in your application, but
+ you have to do it yourself. The two primary strategies are either denormalizing the data upon writing to HBase,
+ or to have lookup tables and do the join between HBase tables in your application or MapReduce code (and as RDBMS'
+ demonstrate, there are several strategies for this depending on the size of the tables, e.g., nested loops vs.
+ hash-joins). So which is the best approach? It depends on what you are trying to do, and as such there isn't a single
+ answer that works for every use case.
+
+
@@ -756,6 +769,10 @@
+ Joins
+ If you have multiple tables, don't forget to factor in the potential for into the schema design.
+
+
Time To Live (TTL)
ColumnFamilies can set a TTL length in seconds, and HBase will automatically delete rows once the expiration time is reached.