<s>
Volt	O
Active	O
Data	O
(	O
formerly	O
VoltDB	B-Application
)	O
is	O
an	O
in-memory	B-General_Concept
database	I-General_Concept
designed	O
by	O
Michael	O
Stonebraker	O
,	O
Sam	O
Madden	O
,	O
and	O
Daniel	O
Abadi	O
.	O
</s>
<s>
It	O
is	O
an	O
ACID-compliant	O
RDBMS	B-Application
that	O
uses	O
a	O
shared-nothing	B-Operating_System
architecture	I-Operating_System
,	O
and	O
is	O
derived	O
from	O
work	O
done	O
by	O
Stonebraker	O
on	O
OLTP	B-General_Concept
system	O
performance	O
and	O
optimization	O
.	O
</s>
<s>
The	O
community	O
edition	O
is	O
licensed	O
under	O
the	O
GNU	B-Application
Affero	I-Application
General	I-Application
Public	I-Application
License	I-Application
.	O
</s>
<s>
VoltDB	B-Application
is	O
a	O
NewSQL	B-General_Concept
OLTP	B-General_Concept
relational	B-Application
database	I-Application
that	O
supports	O
SQL	B-Language
access	O
from	O
within	O
pre-compiled	O
Java	B-Language
stored	I-Language
procedures	I-Language
.	O
</s>
<s>
While	O
direct	O
SQL	B-Language
access	O
is	O
supported	O
,	O
the	O
most	O
efficient	O
form	O
of	O
interaction	O
is	O
using	O
stored	O
procedure	O
calls	O
,	O
as	O
it	O
involves	O
fewer	O
network	O
trips	O
.	O
</s>
<s>
Stored	O
procedures	O
are	O
written	O
in	O
Java	B-Language
by	O
extending	O
a	O
class	O
called	O
'	O
and	O
implementing	O
a	O
‘	O
run( )	O
’	O
method	O
that	O
includes	O
both	O
SQL	B-Language
statements	O
and	O
supporting	O
Java	B-Language
logic	O
.	O
</s>
<s>
Internally	O
data	O
is	O
managed	O
by	O
a	O
C++	B-Language
core	O
to	O
avoid	O
garbage	O
collection	O
issues	O
.	O
</s>
<s>
VoltDB	B-Application
relies	O
on	O
horizontal	O
partitioning	B-General_Concept
down	O
to	O
the	O
individual	O
hardware	O
thread	O
to	O
scale	O
,	O
k-safety	O
(	O
synchronous	O
replication	O
)	O
to	O
provide	O
high	O
availability	O
,	O
and	O
a	O
combination	O
of	O
continuous	O
snapshots	B-Application
and	O
command	O
logging	O
for	O
durability	B-General_Concept
(	O
crash	O
recovery	O
)	O
.	O
</s>
<s>
VoltDB	B-Application
is	O
based	O
on	O
H-Store	B-Application
.	O
</s>
<s>
It	O
uses	O
a	O
shared-nothing	B-Operating_System
architecture	I-Operating_System
to	O
scale	O
.	O
</s>
<s>
Data	O
and	O
the	O
processing	O
associated	O
with	O
it	O
are	O
distributed	O
across	O
the	O
CPU	O
cores	O
within	O
the	O
servers	O
composing	O
a	O
single	O
VoltDB	B-Application
cluster	O
.	O
</s>
<s>
By	O
extending	O
its	O
shared-nothing	B-Operating_System
foundation	O
to	O
the	O
per-core	O
level	O
,	O
VoltDB	B-Application
scales	O
with	O
the	O
increasing	O
core-per-CPU	O
counts	O
on	O
multi-core	O
servers	O
.	O
</s>
<s>
By	O
making	O
stored	O
procedures	O
the	O
unit	O
of	O
transaction	O
and	O
executing	O
them	O
at	O
the	O
partition	B-General_Concept
containing	O
the	O
necessary	O
data	O
,	O
it	O
is	O
possible	O
to	O
eliminate	O
round	O
trip	O
messaging	O
between	O
SQL	B-Language
statements	O
.	O
</s>
<s>
Because	O
data	O
is	O
in	O
memory	O
and	O
local	O
to	O
the	O
partition	B-General_Concept
,	O
a	O
stored	O
procedure	O
can	O
execute	O
in	O
microseconds	O
.	O
</s>
<s>
VoltDB	B-Application
's	O
stored	O
procedure	O
initiation	O
scheme	O
allows	O
all	O
nodes	O
to	O
initiate	O
stored	O
procedures	O
while	O
avoiding	O
a	O
single	O
serializable	O
global	O
order	O
.	O
</s>
<s>
VoltDB	B-Application
is	O
ACID	O
compliant	O
.	O
</s>
<s>
Durability	B-General_Concept
is	O
ensured	O
by	O
continuous	O
snapshots	B-Application
;	O
asynchronous	O
command	O
logging	O
,	O
which	O
creates	O
both	O
snapshots	B-Application
and	O
a	O
log	O
of	O
transactions	O
between	O
snapshots	B-Application
;	O
and	O
synchronous	O
command	O
logging	O
,	O
which	O
logs	O
transactions	O
after	O
the	O
transaction	O
completes	O
and	O
before	O
it	O
is	O
committed	O
to	O
the	O
database	O
.	O
</s>
<s>
VoltDB	B-Application
v5.0	O
introduced	O
a	O
database	O
monitoring	O
and	O
management	O
tool	O
,	O
the	O
VoltDB	B-Application
Management	O
Center	O
(	O
VMC	O
for	O
short	O
)	O
.	O
</s>
<s>
VMC	O
provides	O
browser-based	O
one-stop	O
monitoring	O
and	O
configuration	O
management	O
of	O
the	O
VoltDB	B-Application
database	O
,	O
including	O
graphs	O
for	O
cluster	O
throughput	O
and	O
latency	O
as	O
well	O
as	O
CPU	O
and	O
memory	O
usage	O
for	O
the	O
current	O
server	O
.	O
</s>
<s>
VoltDB	B-Application
version	O
5.1	O
,	O
released	O
in	O
March	O
2015	O
,	O
introduced	O
database	B-General_Concept
replication	I-General_Concept
(	O
DR	O
)	O
functionality	O
,	O
removing	O
any	O
single	O
point	O
of	O
failure	O
.	O
</s>
<s>
DR	O
provides	O
simultaneous	O
,	O
parallel	O
replication	O
of	O
multiple	O
partitions	B-General_Concept
and	O
binary	O
logs	O
of	O
transaction	O
results	O
,	O
saving	O
the	O
replica	O
from	O
having	O
to	O
replay	O
the	O
transaction	O
.	O
</s>
<s>
(	O
August	O
28	O
,	O
2017	O
)	O
introduced	O
User-Defined	O
SQL	B-Language
Functions	I-Language
,	O
allowing	O
customers	O
to	O
write	O
custom	O
functions	O
in	O
Java	B-Language
and	O
make	O
them	O
callable	O
from	O
a	O
SQL	B-Language
statement	O
.	O
</s>
<s>
Schedule	O
Tasks	O
has	O
an	O
easy	O
to	O
use	O
interface	O
for	O
calling	O
pre-defined	O
procedures	O
and	O
can	O
also	O
be	O
fully	O
customized	O
in	O
Java	B-Language
to	O
create	O
more	O
complex	O
schedules	O
.	O
</s>
<s>
V10.0	O
(	O
August	O
,	O
2020	O
)	O
introduced	O
a	O
Volt	O
Operator	O
for	O
Kubernetes	B-General_Concept
and	O
Helm	O
Charts	O
offering	O
a	O
complete	O
solution	O
for	O
running	O
VoltDB	B-Application
databases	O
in	O
a	O
Kubernetes	B-General_Concept
cloud	O
environment	O
.	O
</s>
<s>
V10.2	O
(	O
January	O
2021	O
)	O
introduced	O
VoltDB	B-Application
Topics	O
to	O
provide	O
the	O
intelligent	O
streaming	O
of	O
VoltDB	B-Application
's	O
existing	O
import	O
and	O
export	O
capabilities	O
,	O
but	O
with	O
the	O
flexibility	O
of	O
Kafka-like	O
streams	O
.	O
</s>
<s>
(	O
April	O
21	O
,	O
2022	O
)	O
introduces	O
connectivity	O
to	O
DataDog	O
,	O
support	O
for	O
Java	B-Language
17	O
,	O
compatibility	O
with	O
Kubernetes	B-General_Concept
22.0	O
and	O
priority	O
transactions	O
.	O
</s>
