Database Reference
In-Depth Information
NooSQL
“NoSQL” is a general name for the collection of databases that do not use Structured Query
Language (SQL) or a relational data model. It is sometimes used to mean “Not OnlySQL”
to indicate that the proponents of various nonrelational databases do not suggest that rela-
tional databases are a bad choice—but rather that they are not the only choice for data stor-
age. This term was coined by Cassandra committer Eric Evans of Rackspace, but he has since
distanced himself from the term in preference of the term “Big Data” to highlight the fact
that this family of nonrelational databases is defined not by what they're not (implementa-
tions of SQL), but rather by what they do (handle huge data loads). This term, in my view,
has reached the end of its useful life, because it's confusing. It has proven too tempting to
discuss a set of databases together that really have few goals, design decisions, or features in
common. Let Cassandra be Cassandra, let CouchDB be CouchDB, and let Riak be Riak.
Order--Preserviing P
g Parttiittiioner
This is a kind of Partitioner that stores rows by key order, aligning the physical structure of
the data with your sort order. Configuring your column family to use order-preserving parti-
tioning allows you to perform range slices, meaning that Cassandra knows which nodes have
which keys.
This partitioner is somewhat the opposite of the Random Partitioner ; it has the advantage of
allowing for efficient range queries, but the disadvantage of unevenly distributing keys.
The
order-preserving
partitioner
(OPP)
is
implemented
by
the
org.apache.cassandra.dht.OrderPreservingPartitioner class.
There is a special kind of OPP called the collatingorder-preservingpartitioner(COPP).
This acts like a regular OPP, but sorts the data in a collated manner according to English/
US lexicography instead of byte ordering. For this reason, it is useful for locale-aware
applications.
The
COPP
is
implemented
by
the
org.apache.cassandra.dht.CollatingOrderPreservingPartitioner class.
This
is
implemented
in
Cassandra
by
org.apache.cassandra.dht.OrderPreservingPartitioner .
See also Token .
Parttiittiion
In general terms, a partition refers to a networkpartition, which is a break in the network that
prevents one machine from interacting directly with another. A partition can be caused by
failed switches, routers, or network interfaces. Consider a cluster of five machines {A, B, C,
D, E} where {A, B} are on one subnet and {C, D, E} are on a second subnet. If the switch
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