<s>
Apache	B-Application
Ignite	I-Application
is	O
a	O
distributed	O
database	O
management	O
system	O
for	O
high-performance	O
computing	O
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
's	O
database	O
utilizes	O
RAM	B-Architecture
as	O
the	O
default	O
storage	O
and	O
processing	O
tier	O
,	O
thus	O
,	O
belonging	O
to	O
the	O
class	O
of	O
in-memory	B-General_Concept
computing	I-General_Concept
platforms	B-Device
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
cluster	O
can	O
be	O
deployed	O
on-premise	O
on	O
a	O
commodity	O
hardware	O
,	O
in	O
the	O
cloud	O
(	O
e.g.	O
</s>
<s>
Microsoft	B-Application
Azure	I-Application
,	O
AWS	B-Application
,	O
Google	B-General_Concept
Compute	I-General_Concept
Engine	I-General_Concept
)	O
or	O
in	O
a	O
containerized	O
and	O
provisioning	O
environments	O
such	O
as	O
Kubernetes	B-General_Concept
,	O
Docker	B-Language
,	O
Apache	B-General_Concept
Mesos	I-General_Concept
,	O
VMware	O
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
was	O
developed	O
by	O
GridGain	O
Systems	O
,	O
Inc	O
.	O
and	O
made	O
open	O
source	O
in	O
2014	O
.	O
</s>
<s>
GridGain	O
continues	O
to	O
be	O
the	O
main	O
contributor	O
to	O
the	O
source	O
code	O
,	O
and	O
offers	O
both	O
a	O
commercial	O
version	O
and	O
professional	O
services	O
around	O
Apache	B-Application
Ignite	I-Application
.	O
</s>
<s>
Once	O
donated	O
as	O
open	O
source	O
,	O
Ignite	O
was	O
accepted	O
in	O
the	O
Apache	B-Application
Incubator	I-Application
program	O
in	O
October	O
of	O
2014	O
.	O
</s>
<s>
In	O
recent	O
years	O
,	O
Apache	B-Application
Ignite	I-Application
has	O
become	O
one	O
of	O
the	O
top	O
5	O
most	O
active	O
projects	O
by	O
some	O
metrics	O
,	O
including	O
user	O
base	O
activity	O
and	O
repository	O
size	O
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
clustering	O
component	O
uses	O
a	O
shared	B-Operating_System
nothing	I-Operating_System
architecture	I-Operating_System
.	O
</s>
<s>
Client	O
nodes	O
are	O
usually	O
embedded	O
in	O
the	O
application	O
code	O
written	O
in	O
Java	B-Language
,	O
C#	B-Application
or	O
C++	B-Language
that	O
have	O
special	O
libraries	O
developed	O
.	O
</s>
<s>
On	O
top	O
of	O
its	O
distributed	O
foundation	O
,	O
Apache	B-Application
Ignite	I-Application
supports	O
interfaces	O
including	O
JCache-compliant	O
key-value	O
APIs	O
,	O
ANSI-99	B-Language
SQL	B-Language
with	O
joins	B-Language
,	O
ACID	O
transactions	O
,	O
as	O
well	O
as	O
MapReduce	B-Operating_System
like	O
computations	O
.	O
</s>
<s>
Ignite	O
provides	O
ODBC	B-Application
,	O
JDBC	B-Language
and	O
REST	O
drivers	O
as	O
a	O
way	O
to	O
work	O
with	O
the	O
database	O
from	O
other	O
programming	O
languages	O
or	O
tools	O
.	O
</s>
<s>
Every	O
cache	O
is	O
split	O
into	O
a	O
fixed	O
set	O
of	O
"	O
partitions	O
"	O
that	O
are	O
evenly	O
distributed	O
among	O
cluster	O
nodes	O
using	O
the	O
rendezvous	B-Algorithm
hashing	I-Algorithm
algorithm	O
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
maps	O
a	O
pair	O
to	O
a	O
partition	O
by	O
taking	O
the	O
key	O
's	O
value	O
and	O
passing	O
it	O
to	O
a	O
special	O
hash	B-Error_Name
function	I-Error_Name
.	O
</s>
<s>
The	O
memory	O
architecture	O
in	O
Apache	B-Application
Ignite	I-Application
consists	O
of	O
two	O
storage	O
tiers	O
and	O
is	O
called	O
"	O
durable	O
memory	O
"	O
.	O
</s>
<s>
Internally	O
,	O
it	O
uses	O
paging	B-Architecture
for	O
memory	O
space	O
management	O
and	O
data	O
reference	O
,	O
similar	O
to	O
the	O
virtual	B-Architecture
memory	I-Architecture
of	O
systems	O
like	O
Unix	B-Application
.	O
</s>
<s>
However	O
,	O
one	O
significant	O
difference	O
between	O
the	O
durable	O
and	O
virtual	B-Architecture
memory	I-Architecture
architectures	O
is	O
that	O
the	O
former	O
always	O
keeps	O
the	O
whole	O
data	O
set	O
with	O
indexes	O
on	O
disk	O
(	O
assuming	O
that	O
the	O
disk	O
tier	O
is	O
enabled	O
)	O
,	O
while	O
the	O
virtual	B-Architecture
memory	I-Architecture
uses	O
the	O
disk	O
when	O
it	O
runs	O
out	O
of	O
RAM	B-Architecture
,	O
for	O
swapping	O
purposes	O
only	O
.	O
</s>
<s>
The	O
first	O
tier	O
of	O
the	O
memory	O
architecture	O
,	O
memory	O
tier	O
,	O
keeps	O
data	O
and	O
indexes	O
in	O
RAM	B-Architecture
out	O
of	O
Java	B-Language
heap	O
in	O
so-called	O
"	O
off-heap	O
regions	O
"	O
.	O
</s>
<s>
The	O
regions	O
are	O
preallocated	O
and	O
managed	O
by	O
the	O
database	O
on	O
its	O
own	O
which	O
prevents	O
Java	B-Language
heap	O
utilization	O
for	O
storage	O
needs	O
,	O
as	O
a	O
result	O
,	O
helping	O
to	O
avoid	O
long	O
garbage	O
collection	O
pauses	O
.	O
</s>
<s>
The	O
regions	O
are	O
split	O
into	O
pages	B-General_Concept
of	O
fixed	O
size	O
that	O
store	O
data	O
,	O
indexes	O
,	O
and	O
system	O
metadata	O
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
is	O
fully	O
operational	O
from	O
the	O
memory	O
tier	O
but	O
it	O
is	O
always	O
possible	O
to	O
use	O
the	O
second	O
tier	O
,	O
disk	O
tier	O
,	O
for	O
the	O
sake	O
of	O
durability	B-General_Concept
.	O
</s>
<s>
The	O
database	O
comes	O
with	O
its	O
own	O
native	O
persistence	O
and	O
,	O
plus	O
,	O
can	O
use	O
RDBMS	O
,	O
NoSQL	B-General_Concept
or	O
Hadoop	B-Application
databases	O
as	O
its	O
disk	O
tier	O
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
native	O
persistence	O
is	O
a	O
distributed	O
and	O
strongly	B-General_Concept
consistent	I-General_Concept
disk	O
store	O
that	O
always	O
holds	O
a	O
superset	O
of	O
data	O
and	O
indexes	O
on	O
disk	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
there	O
are	O
1000	O
entries	O
and	O
the	O
memory	O
tier	O
can	O
fit	O
only	O
300	O
of	O
them	O
,	O
then	O
all	O
1000	O
will	O
be	O
stored	O
on	O
disk	O
and	O
only	O
300	O
will	O
be	O
cached	O
in	O
RAM	B-Architecture
.	O
</s>
<s>
Persistence	O
uses	O
the	O
write-ahead	B-Algorithm
logging	I-Algorithm
(	O
WAL	O
)	O
technique	O
for	O
keeping	O
immediate	O
data	O
modifications	O
on	O
disk	O
.	O
</s>
<s>
In	O
the	O
background	O
,	O
the	O
store	O
runs	O
the	O
"	O
checkpointing	O
process	O
"	O
which	O
purpose	O
is	O
to	O
copy	O
dirty	O
pages	B-General_Concept
from	O
the	O
memory	O
tier	O
to	O
the	O
partition	O
files	O
.	O
</s>
<s>
Before	O
that	O
Apache	B-Application
Ignite	I-Application
supported	O
only	O
third-party	O
databases	O
as	O
its	O
disk	O
tier	O
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
can	O
be	O
configured	O
as	O
the	O
in-memory	O
tier	O
on	O
top	O
of	O
RDBMS	O
,	O
NoSQL	B-General_Concept
or	O
Hadoop	B-Application
databases	O
speeding	O
up	O
the	O
latter	O
.	O
</s>
<s>
For	O
instance	O
,	O
SQL	B-Language
queries	B-Language
will	O
be	O
executed	O
only	O
on	O
the	O
data	O
that	O
is	O
in	O
RAM	B-Architecture
,	O
thus	O
,	O
requiring	O
to	O
preload	O
all	O
the	O
data	O
set	O
from	O
disk	O
to	O
memory	O
beforehand	O
.	O
</s>
<s>
When	O
using	O
pure	O
memory	O
storage	O
,	O
it	O
is	O
possible	O
for	O
the	O
data	O
size	O
to	O
exceed	O
the	O
physical	O
RAM	B-Architecture
size	O
,	O
leading	O
to	O
Out-Of-Memory	O
Errors	O
(	O
OOMEs	O
)	O
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
is	O
a	O
strongly	B-General_Concept
consistent	I-General_Concept
platform	O
that	O
implements	O
two-phase	B-General_Concept
commit	I-General_Concept
protocol	I-General_Concept
.	O
</s>
<s>
Transactions	O
in	O
Apache	B-Application
Ignite	I-Application
are	O
ACID-compliant	O
and	O
can	O
span	O
multiple	O
cluster	O
nodes	O
and	O
caches	O
.	O
</s>
<s>
The	O
database	O
supports	O
pessimistic	O
and	O
optimistic	O
concurrency	O
modes	O
,	O
deadlock-free	O
transactions	O
and	O
deadlock	B-Operating_System
detection	O
techniques	O
.	O
</s>
<s>
In	O
the	O
scenarios	O
where	O
transactional	O
guarantees	O
are	O
optional	O
,	O
Apache	B-Application
Ignite	I-Application
allows	O
executing	O
queries	B-Language
in	O
the	O
atomic	O
mode	O
that	O
provides	O
better	O
performance	O
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
can	O
be	O
accessed	O
using	O
SQL	B-Language
APIs	O
exposed	O
via	O
JDBC	B-Language
and	O
ODBC	B-Application
drivers	O
,	O
and	O
native	O
libraries	O
developed	O
for	O
Java	B-Language
,	O
C#	B-Application
,	O
C++	B-Language
programming	I-Language
languages	I-Language
.	O
</s>
<s>
Both	O
data	B-Language
manipulation	I-Language
and	O
data	B-Language
definition	I-Language
languages	I-Language
 '	O
syntax	O
complies	O
with	O
ANSI-99	B-Language
specification	O
.	O
</s>
<s>
Being	O
a	O
distributed	O
database	O
,	O
Apache	B-Application
Ignite	I-Application
supports	O
both	O
distributed	O
collocated	O
and	O
non-collocated	O
joins	B-Language
.	O
</s>
<s>
When	O
the	O
data	O
is	O
collocated	O
,	O
joins	B-Language
are	O
executed	O
on	O
the	O
local	O
data	O
of	O
cluster	O
nodes	O
avoiding	O
data	O
movement	O
across	O
the	O
network	O
.	O
</s>
<s>
Non-collocated	O
joins	B-Language
might	O
move	O
the	O
data	O
sets	O
around	O
the	O
network	O
in	O
order	O
to	O
prepare	O
a	O
consistent	O
result	O
set	O
.	O
</s>
<s>
Apache	B-Application
Ignite	I-Application
provides	O
machine	O
learning	O
training	O
and	O
inference	O
functionality	O
as	O
well	O
as	O
data	B-General_Concept
preprocessing	I-General_Concept
and	O
model	O
quality	O
estimation	O
.	O
</s>
<s>
It	O
natively	O
supports	O
classical	O
training	O
algorithms	O
such	O
as	O
Linear	B-General_Concept
Regression	I-General_Concept
,	O
Decision	B-Algorithm
Trees	I-Algorithm
,	O
Random	B-Algorithm
Forest	I-Algorithm
,	O
Gradient	B-Algorithm
Boosting	I-Algorithm
,	O
SVM	B-Algorithm
,	O
K-Means	B-Algorithm
and	O
others	O
.	O
</s>
<s>
In	O
addition	O
to	O
that	O
,	O
Apache	B-Application
Ignite	I-Application
has	O
a	O
deep	O
integration	O
with	O
TensorFlow	B-Language
.	O
</s>
<s>
This	O
integrations	O
allows	O
to	O
train	O
neural	O
networks	O
on	O
a	O
data	O
stored	O
in	O
Apache	B-Application
Ignite	I-Application
in	O
a	O
single-node	O
or	O
distributed	O
manner	O
.	O
</s>
<s>
The	O
key	O
idea	O
of	O
Apache	B-Application
Ignite	I-Application
Machine	O
Learning	O
toolkit	O
is	O
an	O
ability	O
to	O
perform	O
distributed	O
training	O
and	O
inference	O
instantly	O
without	O
massive	O
data	O
transmissions	O
.	O
</s>
<s>
It	O
's	O
based	O
on	O
MapReduce	B-Operating_System
approach	O
,	O
resilient	O
to	O
node	O
failures	O
and	O
data	O
rebalances	O
,	O
allows	O
to	O
avoid	O
data	O
transfers	O
and	O
so	O
that	O
speed	O
up	O
preprocessing	O
and	O
model	O
training	O
.	O
</s>
