<s>
An	O
Ordered	B-General_Concept
Key-Value	I-General_Concept
Store	I-General_Concept
(	O
OKVS	O
)	O
is	O
a	O
type	O
of	O
data	O
storage	O
paradigm	O
that	O
can	O
support	O
multi-model	B-Operating_System
database	I-Operating_System
.	O
</s>
<s>
It	O
is	O
a	O
more	O
powerful	O
paradigm	O
than	O
Key-Value	B-Data_Structure
Store	I-Data_Structure
because	O
OKVS	O
allow	O
to	O
build	O
higher	O
level	O
abstractions	O
without	O
the	O
need	O
to	O
do	O
full	O
scans	O
.	O
</s>
<s>
Some	O
OKVS	O
are	O
distributed	B-Operating_System
databases	I-Operating_System
.	O
</s>
<s>
Ordered	B-General_Concept
Key-Value	I-General_Concept
Store	I-General_Concept
found	O
their	O
way	O
into	O
many	O
modern	O
database	O
systems	O
including	O
NewSQL	B-General_Concept
database	O
systems	O
.	O
</s>
<s>
The	O
origin	O
of	O
Ordered	B-General_Concept
Key-Value	I-General_Concept
Store	I-General_Concept
stems	O
from	O
the	O
work	O
of	O
Ken	O
Thompson	O
on	O
dbm	B-General_Concept
in	O
1979	O
.	O
</s>
<s>
Later	O
in	O
1991	O
,	O
Berkeley	B-Language
DB	I-Language
was	O
released	O
that	O
featured	O
a	O
B-Tree	B-Architecture
backend	O
that	O
allowed	O
the	O
keys	O
to	O
stay	O
sorted	O
.	O
</s>
<s>
Berkeley	B-Language
DB	I-Language
was	O
said	O
to	O
be	O
very	O
fast	O
and	O
made	O
its	O
way	O
into	O
various	O
commercial	O
product	O
.	O
</s>
<s>
In	O
2009	O
,	O
Tokyo	B-Language
Cabinet	I-Language
was	O
released	O
that	O
was	O
superseded	O
by	O
Kyoto	B-Language
Cabinet	I-Language
that	O
support	O
both	O
transaction	O
and	O
ordered	O
keys	O
.	O
</s>
<s>
In	O
2011	O
,	O
LMDB	B-Language
was	O
created	O
to	O
replace	O
Berkeley	B-Language
DB	I-Language
in	O
OpenLDAP	B-Language
.	O
</s>
<s>
There	O
is	O
also	O
Google	O
's	O
LevelDB	B-Language
that	O
was	O
forked	O
by	O
Facebook	O
in	O
2012	O
as	O
RocksDB	B-Language
.	O
</s>
<s>
In	O
2014	O
,	O
WiredTiger	B-Application
,	O
successor	O
of	O
Berkeley	B-Language
DB	I-Language
was	O
acquired	O
by	O
MongoDB	B-Application
and	O
is	O
since	O
2019	O
the	O
primary	O
backend	O
of	O
MongoDB	B-Application
database	O
.	O
</s>
<s>
Another	O
notable	O
use	O
of	O
OKVS	O
paradigm	O
is	O
the	O
multi-model	B-Operating_System
database	I-Operating_System
system	O
called	O
ArangoDB	B-Operating_System
based	O
on	O
RocksDB	B-Language
.	O
</s>
<s>
Some	O
NewSQL	B-General_Concept
databases	O
are	O
supported	O
by	O
Ordered	B-General_Concept
Key-Value	I-General_Concept
Stores	I-General_Concept
.	O
</s>
<s>
JanusGraph	B-Operating_System
,	O
a	O
property	O
graph	O
database	O
,	O
has	O
both	O
a	O
Berkeley	B-Language
DB	I-Language
backend	O
and	O
FoundationDB	B-Operating_System
backend	O
.	O
</s>
<s>
That	O
is	O
,	O
one	O
can	O
work	O
with	O
an	O
Ordered	B-General_Concept
Key-Value	I-General_Concept
Store	I-General_Concept
without	O
having	O
to	O
fiddle	O
with	O
bytes	O
directly	O
.	O
</s>
<s>
In	O
FoundationDB	B-Operating_System
,	O
it	O
is	O
called	O
the	O
tuple	O
layer	O
.	O
</s>
<s>
The	O
following	O
abstraction	O
or	O
databases	O
were	O
built	O
on	O
top	O
Ordered	B-General_Concept
Key-Value	I-General_Concept
Stores	I-General_Concept
:	O
</s>
<s>
Record	O
Database	O
,	O
also	O
known	O
as	O
Row	O
store	O
databases	O
,	O
they	O
behave	O
similarly	O
to	O
what	O
is	O
dubbed	O
RDBMS	B-Application
,	O
</s>
<s>
Document	O
database	O
,	O
that	O
mimics	O
MongoDB	B-Application
API	O
,	O
</s>
