<s>
RavenDB	B-Operating_System
is	O
an	O
open-source	O
fully	O
ACID	O
document-oriented	B-General_Concept
database	I-General_Concept
written	O
in	O
C#	B-Application
,	O
developed	O
by	O
Hibernating	O
Rhinos	O
Ltd	O
.	O
</s>
<s>
It	O
is	O
cross-platform	B-Operating_System
,	O
supported	O
on	O
Windows	O
,	O
Linux	B-Application
,	O
and	O
Mac	B-Application
OS	I-Application
.	O
</s>
<s>
RavenDB	B-Operating_System
stores	O
data	O
as	O
JSON	B-General_Concept
documents	O
and	O
can	O
be	O
deployed	O
in	O
distributed	B-Operating_System
clusters	I-Operating_System
with	O
master-master	O
replication	O
.	O
</s>
<s>
Originally	O
named	O
"	O
Rhino	O
DivanDB	O
"	O
,	O
RavenDB	B-Operating_System
began	O
in	O
2008	O
as	O
a	O
project	O
by	O
Oren	O
Eini	O
(	O
aka	O
Ayende	O
Rahien	O
)	O
and	O
is	O
developed	O
by	O
Hibernating	O
Rhinos	O
Ltd	O
.	O
</s>
<s>
The	O
company	O
claims	O
it	O
was	O
the	O
first	O
document	B-General_Concept
database	I-General_Concept
to	O
run	O
natively	O
in	O
the	O
.NET	B-Application
Framework	I-Application
.	O
</s>
<s>
It	O
was	O
an	O
early	O
document	B-General_Concept
database	I-General_Concept
to	O
offer	O
ACID	O
guarantees	O
.	O
</s>
<s>
In	O
2019	O
,	O
Hibernating	O
Rhinos	O
began	O
offering	O
RavenDB	B-Operating_System
as	O
a	O
cloud	O
service	O
named	O
RavenDB	B-Operating_System
Cloud	O
.	O
</s>
<s>
Data	O
is	O
stored	O
as	O
schemaless	O
documents	O
in	O
JSON	B-General_Concept
format	O
.	O
</s>
<s>
Some	O
operations	O
at	O
the	O
cluster	O
level	O
require	O
a	O
consensus	O
of	O
a	O
majority	O
of	O
nodes	O
;	O
consensus	O
is	O
determined	O
using	O
an	O
implementation	O
of	O
the	O
Raft	B-Operating_System
algorithm	O
called	O
Rachis	O
.	O
</s>
<s>
RavenDB	B-Operating_System
originally	O
used	O
the	O
ESENT	B-Application
storage	O
engine	O
.	O
</s>
<s>
Clients	O
are	O
supported	O
for	O
C#	B-Application
,	O
C++	B-Language
,	O
Java	B-Language
,	O
NodeJS	B-Language
,	O
Python	B-Language
,	O
Ruby	B-Language
,	O
and	O
Go	B-Application
.	O
</s>
<s>
Queries	O
are	O
expressed	O
in	O
LINQ	B-Language
or	O
with	O
a	O
custom	O
query	B-Language
language	I-Language
named	O
RQL	O
(	O
stands	O
for	O
Raven	O
Query	B-Language
Language	I-Language
)	O
with	O
syntax	O
similar	O
to	O
SQL	B-Language
.	O
</s>
<s>
Dynamic	O
indexes	O
-	O
in	O
RavenDB	B-Operating_System
is	O
that	O
queries	O
can	O
only	O
be	O
satisfied	O
by	O
an	O
index	O
;	O
if	O
no	O
appropriate	O
index	O
exists	O
,	O
a	O
new	O
index	O
is	O
created	O
to	O
satisfy	O
the	O
query	O
.	O
</s>
<s>
Projection	O
-	O
indexes	O
can	O
be	O
configured	O
to	O
transform	O
indexed	O
data	O
,	O
perform	O
calculations	O
,	O
perform	O
aggregations	O
,	O
and	O
execute	O
JavaScript	B-Language
code	O
on	O
the	O
server	O
side	O
.	O
</s>
<s>
Documents	O
can	O
be	O
extended	O
with	O
other	O
data	O
types	O
less	O
suited	O
to	O
JSON	B-General_Concept
.	O
</s>
<s>
RavenDB	B-Operating_System
Cloud	O
is	O
a	O
managed	O
database-as-a-service	O
launched	O
in	O
2019	O
on	O
AWS	B-Application
,	O
Azure	B-Application
,	O
and	O
GCP	B-General_Concept
.	O
</s>
<s>
RavenDB	B-Operating_System
can	O
also	O
be	O
run	O
as	O
an	O
embedded	O
instance	O
,	O
a	O
great	O
option	O
for	O
smaller	O
applications	O
and	O
proof	O
of	O
concepts	O
,	O
for	O
instance	O
.	O
</s>
<s>
From	O
their	O
Server	O
:	O
Running	O
an	O
Embedded	O
Instance	O
page	O
:	O
"	O
RavenDB	B-Operating_System
makes	O
it	O
very	O
easy	O
to	O
be	O
embedded	O
within	O
your	O
application	O
,	O
with	O
RavenDB	B-Operating_System
Embedded	O
package	O
you	O
can	O
integrate	O
your	O
RavenDB	B-Operating_System
server	O
with	O
a	O
few	O
easy	O
steps.	O
"	O
</s>
<s>
RavenDB	B-Operating_System
is	O
open	O
source	O
under	O
an	O
AGPLv3	B-Application
license	O
.	O
</s>
