<s>
The	O
elasticity	B-Application
of	O
a	O
data	B-General_Concept
store	I-General_Concept
relates	O
to	O
the	O
flexibility	O
of	O
its	O
data	B-Application
model	I-Application
and	O
clustering	B-Architecture
capabilities	O
.	O
</s>
<s>
The	O
greater	O
the	O
number	O
of	O
data	B-Application
model	I-Application
changes	O
that	O
can	O
be	O
tolerated	O
,	O
and	O
the	O
more	O
easily	O
the	O
clustering	B-Architecture
can	O
be	O
managed	O
,	O
the	O
more	O
elastic	O
the	O
data	B-General_Concept
store	I-General_Concept
is	O
considered	O
to	O
be	O
.	O
</s>
<s>
Clustering	B-Architecture
elasticity	B-Application
is	O
the	O
ease	O
of	O
adding	O
or	O
removing	O
nodes	O
from	O
the	O
distributed	O
data	B-General_Concept
store	I-General_Concept
.	O
</s>
<s>
Usually	O
,	O
this	O
is	O
a	O
difficult	O
and	O
delicate	O
task	O
to	O
be	O
done	O
by	O
an	O
expert	O
in	O
a	O
relational	B-Application
database	I-Application
system	O
.	O
</s>
<s>
Some	O
NoSQL	B-General_Concept
data	B-General_Concept
stores	I-General_Concept
,	O
like	O
Apache	B-Application
Cassandra	I-Application
have	O
an	O
easy	O
solution	O
,	O
and	O
a	O
node	O
can	O
be	O
added/removed	O
with	O
a	O
few	O
changes	O
in	O
the	O
properties	O
and	O
by	O
adding	O
specifying	O
at	O
least	O
one	O
seed	O
.	O
</s>
<s>
Relational	B-Application
databases	I-Application
are	O
most	O
often	O
very	O
inelastic	O
,	O
as	O
they	O
have	O
a	O
predefined	O
data	B-Application
model	I-Application
that	O
can	O
only	O
be	O
adapted	O
through	O
redesign	O
.	O
</s>
<s>
Most	O
NoSQL	B-General_Concept
data	B-General_Concept
stores	I-General_Concept
,	O
however	O
,	O
do	O
not	O
have	O
a	O
fixed	O
schema	B-Application
.	O
</s>
<s>
Concerning	O
the	O
data	B-General_Concept
store	I-General_Concept
,	O
modifications	O
in	O
the	O
schema	B-Application
are	O
no	O
problem	O
.	O
</s>
<s>
This	O
makes	O
this	O
kind	O
of	O
data	B-General_Concept
stores	I-General_Concept
more	O
elastic	O
concerning	O
the	O
data	B-Application
model	I-Application
.	O
</s>
<s>
The	O
drawback	O
is	O
that	O
the	O
programmer	O
has	O
to	O
take	O
into	O
account	O
that	O
the	O
data	B-Application
model	I-Application
may	O
change	O
over	O
time	O
.	O
</s>
