<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
is	O
a	O
technology	O
providing	O
shared-nothing	B-Operating_System
clustering	O
and	O
auto-sharding	O
for	O
the	O
MySQL	B-Application
database	B-Application
management	I-Application
system	I-Application
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
is	O
implemented	O
through	O
the	O
NDB	B-Language
or	O
NDBCLUSTER	O
storage	O
engine	O
for	O
MySQL	B-Application
(	O
"	O
NDB	B-Language
"	O
stands	O
for	O
Network	O
Database	O
)	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
is	O
designed	O
around	O
a	O
distributed	O
,	O
multi-master	O
ACID	O
compliant	O
architecture	O
with	O
no	B-Architecture
single	I-Architecture
point	I-Architecture
of	I-Architecture
failure	I-Architecture
.	O
</s>
<s>
Internally	O
MySQL	B-Operating_System
Cluster	I-Operating_System
uses	O
synchronous	O
replication	O
through	O
a	O
two-phase	B-General_Concept
commit	I-General_Concept
mechanism	O
in	O
order	O
to	O
guarantee	O
that	O
data	O
is	O
written	O
to	O
multiple	O
nodes	O
upon	O
committing	O
the	O
data	O
.	O
</s>
<s>
(	O
This	O
is	O
in	O
contrast	O
to	O
what	O
is	O
usually	O
referred	O
to	O
as	O
"	O
MySQL	B-Application
Replication	O
"	O
,	O
which	O
is	O
.	O
)	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
automatically	O
creates	O
“	O
node	O
groups	O
”	O
from	O
the	O
number	O
of	O
replicas	O
and	O
data	O
nodes	O
specified	O
by	O
the	O
user	O
.	O
</s>
<s>
It	O
is	O
also	O
possible	O
to	O
replicate	O
asynchronously	O
between	O
clusters	O
;	O
this	O
is	O
sometimes	O
referred	O
to	O
as	O
"	O
MySQL	B-Operating_System
Cluster	I-Operating_System
Replication	O
"	O
or	O
"	O
geographical	O
replication	O
"	O
.	O
</s>
<s>
This	O
is	O
typically	O
used	O
to	O
replicate	O
clusters	O
between	O
data	O
centers	O
for	O
disaster	B-General_Concept
recovery	I-General_Concept
or	O
to	O
reduce	O
the	O
effects	O
of	O
network	O
latency	O
by	O
locating	O
data	O
physically	O
closer	O
to	O
a	O
set	O
of	O
users	O
.	O
</s>
<s>
Unlike	O
standard	O
MySQL	B-Application
replication	O
,	O
MySQL	B-Operating_System
Cluster	I-Operating_System
's	O
geographic	O
replication	O
uses	O
optimistic	B-Operating_System
concurrency	I-Operating_System
control	I-Operating_System
and	O
the	O
concept	O
of	O
Epochs	O
to	O
provide	O
a	O
mechanism	O
for	O
conflict	O
detection	O
and	O
resolution	O
,	O
enabling	O
active/active	O
clustering	O
between	O
data	O
centers	O
.	O
</s>
<s>
Starting	O
with	O
MySQL	B-Operating_System
Cluster	I-Operating_System
7.2	O
,	O
support	O
for	O
synchronous	O
replication	O
between	O
data	O
centers	O
was	O
supported	O
with	O
the	O
Multi-Site	O
Clustering	O
feature	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
is	O
implemented	O
as	O
a	O
fully	O
distributed	O
multi-master	O
database	O
ensuring	O
updates	O
made	O
by	O
any	O
application	B-Application
or	O
SQL	O
node	O
are	O
instantly	O
available	O
to	O
all	O
of	O
the	O
other	O
nodes	O
accessing	O
the	O
cluster	O
,	O
and	O
each	O
data	O
node	O
can	O
accept	O
write	O
operations	O
.	O
</s>
<s>
Data	O
within	O
MySQL	B-Operating_System
Cluster	I-Operating_System
(	O
NDB	B-Language
)	O
tables	O
is	O
automatically	O
partitioned	B-General_Concept
across	O
all	O
of	O
the	O
data	O
nodes	O
in	O
the	O
system	O
.	O
</s>
<s>
This	O
is	O
done	O
based	O
on	O
a	O
hashing	O
algorithm	O
based	O
on	O
the	O
primary	B-Application
key	I-Application
on	O
the	O
table	B-Application
,	O
and	O
is	O
transparent	O
to	O
the	O
end	O
application	B-Application
.	O
</s>
<s>
Clients	O
can	O
connect	O
to	O
any	O
node	O
in	O
the	O
cluster	O
and	O
have	O
queries	O
automatically	O
access	O
the	O
correct	O
shards	B-General_Concept
needed	O
to	O
satisfy	O
a	O
query	O
or	O
commit	O
a	O
transaction	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
is	O
able	O
to	O
support	O
cross-shard	O
queries	O
and	O
transactions	O
.	O
</s>
<s>
This	O
ensures	O
that	O
data	O
used	O
to	O
complete	O
transactions	O
is	O
localized	O
on	O
the	O
same	O
shard	B-General_Concept
,	O
thereby	O
reducing	O
network	O
hops	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
allows	O
datasets	O
larger	O
than	O
the	O
capacity	O
of	O
a	O
single	O
machine	O
to	O
be	O
stored	O
and	O
accessed	O
across	O
multiple	O
machines	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
maintains	O
all	O
indexed	B-Data_Structure
columns	O
in	O
distributed	O
memory	O
.	O
</s>
<s>
Non-indexed	O
columns	O
can	O
also	O
be	O
maintained	O
in	O
distributed	O
memory	O
or	O
can	O
be	O
maintained	O
on	O
disk	B-Device
with	O
an	O
in-memory	O
page	B-General_Concept
cache	I-General_Concept
.	O
</s>
<s>
Storing	O
non-indexed	O
columns	O
on	O
disk	B-Device
allows	O
MySQL	B-Operating_System
Cluster	I-Operating_System
to	O
store	O
datasets	O
larger	O
than	O
the	O
aggregate	O
memory	O
of	O
the	O
clustered	O
machines	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
writes	O
Redo	B-Application
logs	I-Application
to	O
disk	B-Device
for	O
all	O
data	O
changes	O
as	O
well	O
as	O
check	O
pointing	O
data	O
to	O
disk	B-Device
regularly	O
.	O
</s>
<s>
This	O
allows	O
the	O
cluster	O
to	O
consistently	O
recover	O
from	O
disk	B-Device
after	O
a	O
full	O
cluster	O
outage	O
.	O
</s>
<s>
As	O
the	O
Redo	B-Application
logs	I-Application
are	O
written	O
asynchronously	O
with	O
respect	O
to	O
transaction	O
commit	O
,	O
some	O
small	O
number	O
of	O
transactions	O
can	O
be	O
lost	O
if	O
the	O
full	O
cluster	O
fails	O
,	O
however	O
this	O
can	O
be	O
mitigated	O
by	O
using	O
geographic	O
replication	O
or	O
multi-site	O
cluster	O
discussed	O
above	O
.	O
</s>
<s>
Normal	O
single	B-Architecture
point	I-Architecture
of	I-Architecture
failure	I-Architecture
scenarios	O
do	O
not	O
result	O
in	O
any	O
data	O
loss	O
due	O
to	O
the	O
synchronous	O
data	O
replication	O
within	O
the	O
cluster	O
.	O
</s>
<s>
When	O
a	O
MySQL	B-Operating_System
Cluster	I-Operating_System
table	B-Application
is	O
maintained	O
in	O
memory	O
,	O
the	O
cluster	O
will	O
only	O
access	O
disk	B-Device
storage	O
to	O
write	O
Redo	B-Application
records	O
and	O
checkpoints	O
.	O
</s>
<s>
As	O
these	O
writes	O
are	O
sequential	O
and	O
limited	O
random	O
access	O
patterns	O
are	O
involved	O
,	O
MySQL	B-Operating_System
Cluster	I-Operating_System
can	O
achieve	O
higher	O
write	O
throughput	O
rates	O
with	O
limited	O
disk	B-Device
hardware	O
compared	O
to	O
a	O
traditional	O
disk-based	O
caching	O
RDBMS	B-Application
.	O
</s>
<s>
This	O
checkpointing	O
to	O
disk	B-Device
of	O
in-memory	O
table	B-Application
data	O
can	O
be	O
disabled	O
(	O
on	O
a	O
per-table	O
basis	O
)	O
if	O
disk-based	O
persistence	O
is	O
n't	O
needed	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
is	O
designed	O
to	O
have	O
no	B-Architecture
single	I-Architecture
point	I-Architecture
of	I-Architecture
failure	I-Architecture
.	O
</s>
<s>
Shared	O
disk	B-Device
(	O
SAN	O
)	O
is	O
not	O
required	O
.	O
</s>
<s>
The	O
interconnects	O
between	O
nodes	O
can	O
be	O
standard	O
Ethernet	O
,	O
Gigabit	O
Ethernet	O
,	O
InfiniBand	B-Architecture
,	O
or	O
SCI	B-General_Concept
interconnects	O
.	O
</s>
<s>
As	O
MySQL	B-Operating_System
Cluster	I-Operating_System
stores	O
tables	O
in	O
data	O
nodes	O
,	O
rather	O
than	O
in	O
the	O
MySQL	B-Application
Server	I-Application
,	O
there	O
are	O
multiple	O
interfaces	O
available	O
to	O
access	O
the	O
database	O
:	O
</s>
<s>
NoSQL	O
APIs	B-General_Concept
where	O
MySQL	B-Operating_System
Cluster	I-Operating_System
libraries	O
can	O
be	O
embedded	O
into	O
an	O
application	B-Application
to	O
provide	O
direct	O
access	O
to	O
the	O
data	O
nodes	O
without	O
passing	O
through	O
a	O
SQL	O
layer	O
.	O
</s>
<s>
Part	O
of	O
the	O
commercial	O
MySQL	B-Operating_System
Cluster	I-Operating_System
CGE	O
,	O
MySQL	B-Operating_System
Cluster	I-Operating_System
Manager	O
is	O
a	O
tool	O
designed	O
to	O
simplify	O
the	O
creation	O
and	O
administration	O
of	O
the	O
MySQL	B-Operating_System
Cluster	I-Operating_System
CGE	O
database	O
by	O
automating	O
common	O
management	O
tasks	O
,	O
including	O
on-line	O
scaling	O
,	O
upgrades	O
,	O
backup/restore	O
and	O
reconfiguration	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
Manager	O
also	O
monitors	O
and	O
automatically	O
recovers	O
MySQL	B-Application
Server	I-Application
application	B-Application
nodes	O
and	O
management	O
nodes	O
,	O
as	O
well	O
as	O
the	O
MySQL	B-Operating_System
Cluster	I-Operating_System
data	O
nodes	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
uses	O
three	O
different	O
types	O
of	O
nodes	O
(	O
processes	O
)	O
:	O
</s>
<s>
They	O
can	O
also	O
be	O
configured	O
as	O
arbitrators	O
,	O
but	O
this	O
is	O
not	O
mandatory	O
(	O
MySQL	B-Application
Servers	I-Application
can	O
be	O
configured	O
as	O
arbitrators	O
instead	O
)	O
.	O
</s>
<s>
Application	B-Application
node	O
or	O
SQL	O
node	O
(	O
mysqld	O
process	O
)	O
:	O
A	O
MySQL	B-Application
server	I-Application
(	O
mysqld	O
)	O
that	O
connects	O
to	O
all	O
of	O
the	O
data	O
nodes	O
in	O
order	O
to	O
perform	O
data	O
storage	O
and	O
retrieval	O
.	O
</s>
<s>
This	O
node	O
type	O
is	O
optional	O
;	O
it	O
is	O
possible	O
to	O
query	O
data	O
nodes	O
directly	O
via	O
the	O
NDB	B-Language
API	B-General_Concept
,	O
either	O
natively	O
using	O
the	O
C++	O
API	B-General_Concept
or	O
one	O
of	O
the	O
additional	O
NoSQL	O
APIs	B-General_Concept
described	O
above	O
.	O
</s>
<s>
Generally	O
,	O
it	O
is	O
expected	O
that	O
each	O
node	O
will	O
run	O
on	O
a	O
separate	O
physical	O
host	O
,	O
VM	O
or	O
cloud	O
instance	O
(	O
although	O
it	O
is	O
very	O
common	O
to	O
co-locate	O
Management	O
Nodes	O
with	O
MySQL	B-Application
Servers	I-Application
)	O
.	O
</s>
<s>
For	O
best	O
practice	O
,	O
it	O
is	O
recommended	O
not	O
to	O
co-locate	O
nodes	O
within	O
the	O
same	O
node	O
group	O
on	O
a	O
single	O
physical	O
host	O
(	O
as	O
that	O
would	O
represent	O
a	O
single	B-Architecture
point	I-Architecture
of	I-Architecture
failure	I-Architecture
)	O
.	O
</s>
<s>
From	O
the	O
8.0	O
release	O
onwards	O
,	O
MySQL	B-Operating_System
Cluster	I-Operating_System
is	O
based	O
directly	O
on	O
the	O
corresponding	O
8.0	O
releases	O
of	O
the	O
MySQL	B-Application
Server	I-Application
.	O
</s>
<s>
Previously	O
,	O
MySQL	B-Operating_System
Cluster	I-Operating_System
version	O
numbers	O
were	O
decoupled	O
from	O
those	O
of	O
MySQL	B-Application
Server	I-Application
-	O
for	O
example	O
MySQL	B-Operating_System
Cluster	I-Operating_System
7.6	O
was	O
based	O
on/contained	O
the	O
server	O
component	O
from	O
MySQL	O
5.7	O
.	O
</s>
<s>
Higher	O
versions	O
of	O
MySQL	B-Operating_System
Cluster	I-Operating_System
include	O
all	O
of	O
the	O
features	O
of	O
lower	O
versions	O
,	O
plus	O
some	O
new	O
features	O
.	O
</s>
<s>
Supports	O
255	O
nodes	O
,	O
online	O
table	B-Application
alter	O
,	O
replication	O
latency	O
and	O
throughput	O
enhancements	O
etc	O
.	O
</s>
<s>
Includes	O
compressed	O
backup	O
+	O
LCP	O
,	O
circular	O
replication	O
support	O
,	O
conflict	O
detection/resolution	O
,	O
table	B-Application
optimization	O
etc	O
.	O
</s>
<s>
Includes	O
Adaptive	O
Query	O
Localization	O
(	O
pushes	O
JOIN	O
operations	O
down	O
to	O
the	O
data	O
nodes	O
)	O
,	O
Memcached	O
API	B-General_Concept
,	O
simplified	O
Active/Active	O
Geographic	O
replication	O
,	O
multi-site	O
clustering	O
,	O
data	O
node	O
scalability	O
enhancements	O
,	O
consolidated	O
user	O
privileges	O
.	O
</s>
<s>
Includes	O
support	O
for	O
foreign	B-Application
key	I-Application
constraints	I-Application
,	O
Node.js	B-Language
/	O
JavaScript	B-Language
API	B-General_Concept
and	O
an	O
auto-installer	O
.	O
</s>
<s>
Includes	O
enhanced	O
conflict	O
detection	O
and	O
resolution	O
,	O
improved	O
node	O
restart	O
times	O
,	O
new	O
Event	O
API	B-General_Concept
.	O
</s>
<s>
Improved	O
restart	O
and	O
recovery	O
times	O
,	O
reduced	O
disk	B-Device
space	O
usage	O
,	O
improved	O
join	O
performance	O
,	O
new	O
import	O
tool	O
,	O
shared	O
memory	O
communication	O
,	O
improved	O
topology	O
awareness	O
for	O
cloud	O
.	O
</s>
<s>
Increase	O
in	O
max	O
row	O
size	O
to	O
30kB	O
,	O
Support	O
for	O
up	O
to	O
144	O
data	O
nodes	O
,	O
Improved	O
distributed	O
filtering	O
and	O
joining	O
,	O
Support	O
for	O
parallel	O
outer	O
joins	O
and	O
semi	O
joins	O
,	O
Improved	O
schema	O
and	O
ACL	O
handling	O
,	O
Online	O
column	O
rename	O
,	O
Simplified	O
configuration	O
,	O
Multithreaded	O
parallel	O
backup	O
and	O
restore	O
,	O
Disk	B-Device
data	O
performance	O
improvements	O
,	O
Enhanced	O
support	O
for	O
3	O
and	O
4	O
replica	O
configurations	O
,	O
Support	O
for	O
multi	O
socket	O
mesh	O
networking	O
,	O
Support	O
for	O
restore	O
transformations	O
,	O
Improved	O
Blob	O
write	O
performance	O
,	O
Backup	O
encryption	O
,	O
Support	O
for	O
IPv6	O
,	O
Threading	O
autoconfiguration	O
,	O
Improved	O
recovery	O
performance	O
,	O
Improved	O
query	O
multithreading	O
.	O
</s>
<s>
For	O
evaluation	O
purposes	O
,	O
it	O
is	O
possible	O
to	O
run	O
MySQL	B-Operating_System
Cluster	I-Operating_System
on	O
a	O
single	O
physical	O
server	O
.	O
</s>
<s>
OS	O
:	O
Linux	B-Application
,	O
Solaris	B-Application
,	O
Windows	O
.	O
</s>
<s>
MySQL	B-Application
AB	O
acquired	O
the	O
technology	O
behind	O
MySQL	B-Operating_System
Cluster	I-Operating_System
from	O
Alzato	O
,	O
a	O
small	O
venture	O
company	O
started	O
by	O
Ericsson	O
.	O
</s>
<s>
NDB	B-Language
was	O
originally	O
designed	O
for	O
the	O
telecom	O
market	O
,	O
with	O
its	O
high	O
availability	O
and	O
high	O
performance	O
requirements	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
based	O
on	O
the	O
NDB	B-Language
storage	O
engine	O
has	O
since	O
been	O
integrated	O
into	O
the	O
MySQL	B-Application
product	O
,	O
with	O
its	O
first	O
release	O
being	O
in	O
MySQL	B-Application
4.1	O
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
7.5	O
inside	O
and	O
out	O
.	O
</s>
<s>
Book	O
written	O
by	O
Mikael	O
Ronström	O
,	O
the	O
founder	O
of	O
the	O
NDB	B-Language
technology	O
.	O
</s>
<s>
Pro	O
MySQL	B-Application
NDB	B-Language
Cluster	I-Language
.	O
</s>
<s>
Book	O
written	O
by	O
Jesper	O
Wisborg	O
Krogh	O
and	O
Mikiya	O
Okuno	O
,	O
support	O
engineers	O
of	O
MySQL	B-Application
.	O
</s>
<s>
MySQL	B-Operating_System
Cluster	I-Operating_System
is	O
licensed	O
under	O
the	O
GPLv2	O
license	O
.	O
</s>
<s>
Commercial	O
support	O
is	O
available	O
as	O
part	O
of	O
MySQL	B-Operating_System
Cluster	I-Operating_System
CGE	O
,	O
which	O
also	O
includes	O
non-open	O
source	O
addons	O
such	O
as	O
MySQL	B-Operating_System
Cluster	I-Operating_System
Manager	O
,	O
MySQL	B-Application
Enterprise	O
Monitor	O
,	O
in	O
addition	O
to	O
MySQL	B-Application
Enterprise	O
Security	O
and	O
MySQL	B-Application
Enterprise	O
Audit	O
.	O
</s>
