6.2.  On the number of column families  HBase currently does not
do well with anything above two or three column families so keep
the number of column families in your schema low. Currently,
flushing and compactions are done on a per Region basis so if
one column family is carrying the bulk of the data bringing on
flushes, the adjacent families will also be flushed though the
amount of data they carry is small. When many column families
the flushing and compaction interaction can make for a bunch of
needless i/o loading (To be addressed by changing flushing and
compaction to work on a per column family basis). For more
information on compactions, see Section, “Compaction”.  Try to
make do with one column family if you can in your schemas. Only
introduce a second and third column family in the case where
data access is usually column scoped; i.e. you query one column
family or the other but usually not both at the one time.
6.2.1. Cardinality of ColumnFamilies  Where multiple
ColumnFamilies exist in a single