<s>
The	O
standard	B-Application
column	I-Application
family	I-Application
is	O
a	O
NoSQL	B-General_Concept
object	O
that	O
contains	O
columns	O
of	O
related	O
data	O
.	O
</s>
<s>
It	O
is	O
a	O
tuple	B-Application
(	O
pair	O
)	O
that	O
consists	O
of	O
a	O
key	B-Application
–	I-Application
value	I-Application
pair	I-Application
,	O
where	O
the	O
key	O
is	O
mapped	O
to	O
a	O
value	O
that	O
is	O
a	O
set	O
of	O
columns	O
.	O
</s>
<s>
In	O
analogy	O
with	O
relational	B-Application
databases	I-Application
,	O
a	O
standard	B-Application
column	I-Application
family	I-Application
is	O
as	O
a	O
"	O
table	O
"	O
,	O
each	O
key	B-Application
–	I-Application
value	I-Application
pair	I-Application
being	O
a	O
"	O
row	O
"	O
.	O
</s>
<s>
Each	O
column	B-Application
is	O
a	O
tuple	B-Application
(	O
triplet	O
)	O
consisting	O
of	O
a	O
column	B-Application
name	O
,	O
a	O
value	O
,	O
and	O
a	O
timestamp	O
.	O
</s>
<s>
In	O
a	O
relational	B-Application
database	I-Application
table	O
,	O
this	O
data	O
would	O
be	O
grouped	O
together	O
within	O
a	O
table	O
with	O
other	O
non-related	O
data	O
.	O
</s>
<s>
Standard	B-Application
column	I-Application
families	I-Application
are	O
column	B-Application
containers	O
sorted	O
by	O
their	O
names	O
can	O
be	O
referenced	O
and	O
sorted	O
by	O
their	O
row	O
key	O
.	O
</s>
<s>
Accessing	O
the	O
data	O
in	O
a	O
distributed	B-Architecture
data	B-General_Concept
store	I-General_Concept
would	O
be	O
expensive	O
(	O
time-consuming	O
)	O
,	O
if	O
it	O
would	O
be	O
saved	O
in	O
form	O
of	O
a	O
table	O
.	O
</s>
<s>
It	O
would	O
also	O
be	O
inefficient	O
to	O
read	O
all	O
column	B-Application
families	I-Application
that	O
would	O
make	O
up	O
a	O
row	O
in	O
a	O
relational	B-Application
table	O
and	O
put	O
it	O
together	O
to	O
form	O
a	O
row	O
,	O
as	O
the	O
data	O
for	O
it	O
is	O
distributed	B-Architecture
on	O
a	O
large	O
number	O
of	O
nodes	B-Protocol
.	O
</s>
<s>
As	O
an	O
example	O
,	O
a	O
relational	B-Application
table	O
could	O
consist	O
of	O
the	O
columns	O
UID	O
,	O
first	O
name	O
,	O
surname	O
,	O
birthdate	O
,	O
gender	O
,	O
etc	O
.	O
</s>
<s>
In	O
a	O
distributed	B-Architecture
data	B-General_Concept
store	I-General_Concept
,	O
the	O
same	O
table	O
would	O
be	O
implemented	O
by	O
creating	O
columns	O
families	O
for	O
"	O
UID	O
,	O
first	O
name	O
,	O
surname	O
"	O
,	O
"	O
birthdate	O
,	O
gender	O
"	O
,	O
etc	O
.	O
</s>
<s>
If	O
one	O
needs	O
only	O
the	O
males	O
that	O
were	O
born	O
between	O
1950	O
and	O
1960	O
,	O
for	O
a	O
query	B-Language
in	O
the	O
relational	B-Application
database	I-Application
,	O
all	O
the	O
table	O
has	O
to	O
be	O
read	O
.	O
</s>
<s>
In	O
a	O
distributed	B-Architecture
data	B-General_Concept
store	I-General_Concept
,	O
it	O
suffices	O
to	O
access	O
only	O
the	O
second	O
standard	B-Application
column	I-Application
family	I-Application
,	O
as	O
the	O
rest	O
of	O
information	O
is	O
irrelevant	O
.	O
</s>
<s>
There	O
is	O
no	O
way	O
to	O
sort	O
columns	O
,	O
nor	O
to	O
query	B-Language
an	O
arbitrary	O
query	B-Language
in	O
distributed	B-Architecture
data	B-General_Concept
stores	I-General_Concept
.	O
</s>
<s>
Columns	O
are	O
sorted	O
when	O
they	O
are	O
added	O
to	O
the	O
column	B-Application
family	I-Application
.	O
</s>
<s>
For	O
instance	O
,	O
this	O
is	O
done	O
by	O
the	O
CompareWith	O
attribute	O
in	O
Apache	B-Application
Cassandra	I-Application
that	O
can	O
have	O
the	O
following	O
values	O
:	O
</s>
<s>
Standard	B-Application
column	I-Application
families	I-Application
have	O
a	O
schema-less	O
nature	O
so	O
that	O
each	O
of	O
their	O
"	O
row	O
"	O
s	O
can	O
contain	O
a	O
different	O
number	O
of	O
columns	O
,	O
and	O
even	O
different	O
column	B-Application
names	O
could	O
be	O
in	O
each	O
row	O
.	O
</s>
<s>
So	O
,	O
they	O
are	O
a	O
very	O
different	O
concept	O
than	O
the	O
rows	O
in	O
relational	B-Application
database	I-Application
management	I-Application
system	I-Application
(	O
RDBMS	O
)	O
s	O
.	O
This	O
is	O
one	O
of	O
the	O
reasons	O
why	O
the	O
concept	O
is	O
not	O
trivial	O
for	O
an	O
experienced	O
RDBMS	O
expert	O
.	O
</s>
<s>
In	O
JSON-like	B-General_Concept
notation	O
,	O
a	O
column	B-Application
family	I-Application
definition	O
would	O
look	O
as	O
follows	O
:	O
</s>
<s>
where	O
"	O
Cassandra	B-Application
"	O
,	O
"	O
TerryCho	O
"	O
,	O
"	O
Cath	O
"	O
correspond	O
to	O
row	O
keys	O
;	O
and	O
"	O
emailAddress	O
"	O
,	O
"	O
age	O
"	O
,	O
"	O
gender	O
"	O
,	O
"	O
address	O
"	O
correspond	O
to	O
the	O
column	B-Application
names	O
.	O
</s>
