<s>
Schema-agnostic	B-General_Concept
databases	I-General_Concept
or	O
vocabulary-independent	O
databases	O
aim	O
at	O
supporting	O
users	O
to	O
be	O
abstracted	O
from	O
the	O
representation	O
of	O
the	O
data	O
,	O
supporting	O
the	O
automatic	O
semantic	O
matching	O
between	O
queries	O
and	O
databases	O
.	O
</s>
<s>
The	O
increase	O
in	O
the	O
size	O
and	O
in	O
the	O
semantic	O
heterogeneity	O
of	O
database	O
schemas	O
bring	O
new	O
requirements	O
for	O
users	O
querying	O
and	O
searching	O
structured	B-Application
data	I-Application
.	O
</s>
<s>
The	O
SCoDD	O
trend	O
emerges	O
as	O
a	O
central	O
data	O
management	O
concern	O
in	O
Big	B-Application
Data	I-Application
scenarios	O
,	O
where	O
users	O
and	O
applications	O
have	O
a	O
demand	O
for	O
more	O
complete	O
data	O
,	O
produced	O
by	O
independent	O
data	O
sources	O
,	O
under	O
different	O
semantic	O
assumptions	O
and	O
contexts	O
of	O
use	O
,	O
which	O
is	O
the	O
typical	O
scenario	O
for	O
Semantic	O
Web	O
Data	O
applications	O
.	O
</s>
<s>
The	O
development	O
of	O
approaches	O
to	O
support	O
natural	B-General_Concept
language	I-General_Concept
interfaces	I-General_Concept
(	O
NLI	O
)	O
over	O
databases	O
have	O
aimed	O
towards	O
the	O
goal	O
of	O
schema-agnostic	O
queries	O
.	O
</s>
<s>
While	O
the	O
demand	O
for	O
schema-agnosticism	O
has	O
been	O
an	O
implicit	O
requirement	O
across	O
semantic	O
search	O
and	O
natural	B-General_Concept
language	I-General_Concept
query	I-General_Concept
systems	O
over	O
structured	B-Application
data	I-Application
,	O
it	O
is	O
not	O
sufficiently	O
individuated	O
as	O
a	O
concept	O
and	O
as	O
a	O
necessary	O
requirement	O
for	O
contemporary	O
database	O
management	O
systems	O
.	O
</s>
<s>
Consist	O
of	O
schema-agnostic	O
queries	O
following	O
the	O
syntax	O
of	O
a	O
structured	O
standard	O
(	O
for	O
example	O
SQL	B-Language
,	O
SPARQL	B-Language
)	O
.	O
</s>
<s>
which	O
maps	O
to	O
the	O
following	O
SPARQL	B-Language
query	O
in	O
the	O
dataset	O
vocabulary	O
:	O
</s>
<s>
which	O
maps	O
to	O
the	O
following	O
SPARQL	B-Language
query	O
in	O
the	O
dataset	O
vocabulary	O
:	O
</s>
<s>
Most	O
of	O
schema-agnostic	O
query	O
systems	O
have	O
been	O
investigated	O
in	O
the	O
context	O
of	O
Natural	B-General_Concept
Language	I-General_Concept
Interfaces	I-General_Concept
over	O
databases	O
or	O
over	O
the	O
Semantic	O
Web	O
.	O
</s>
<s>
These	O
works	O
explore	O
the	O
application	O
of	O
semantic	B-Application
parsing	I-Application
techniques	O
over	O
large	O
,	O
heterogeneous	O
and	O
schema-less	O
databases	O
.	O
</s>
