<s>
Online	B-Application
analytical	I-Application
processing	I-Application
,	O
or	O
OLAP	B-Application
(	O
)	O
,	O
is	O
an	O
approach	O
to	O
answer	O
multi-dimensional	B-Algorithm
analytical	I-Algorithm
(	O
MDA	O
)	O
queries	O
swiftly	O
in	O
computing	O
.	O
</s>
<s>
OLAP	B-Application
is	O
part	O
of	O
the	O
broader	O
category	O
of	O
business	B-General_Concept
intelligence	I-General_Concept
,	O
which	O
also	O
encompasses	O
relational	B-Application
databases	I-Application
,	O
report	O
writing	O
and	O
data	B-Application
mining	I-Application
.	O
</s>
<s>
Typical	O
applications	O
of	O
OLAP	B-Application
include	O
business	O
reporting	O
for	O
sales	O
,	O
marketing	O
,	O
management	O
reporting	O
,	O
business	O
process	O
management	O
(	O
BPM	O
)	O
,	O
budgeting	O
and	O
forecasting	O
,	O
financial	O
reporting	O
and	O
similar	O
areas	O
,	O
with	O
new	O
applications	O
emerging	O
,	O
such	O
as	O
agriculture	O
.	O
</s>
<s>
The	O
term	O
OLAP	B-Application
was	O
created	O
as	O
a	O
slight	O
modification	O
of	O
the	O
traditional	O
database	O
term	O
online	B-General_Concept
transaction	I-General_Concept
processing	I-General_Concept
(	O
OLTP	B-General_Concept
)	O
.	O
</s>
<s>
OLAP	B-Application
tools	O
enable	O
users	O
to	O
analyze	O
multidimensional	B-Algorithm
data	I-Algorithm
interactively	O
from	O
multiple	O
perspectives	O
.	O
</s>
<s>
OLAP	B-Application
consists	O
of	O
three	O
basic	O
analytical	O
operations	O
:	O
consolidation	O
(	O
roll-up	O
)	O
,	O
drill-down	O
,	O
and	O
slicing	O
and	O
dicing	O
.	O
</s>
<s>
Slicing	O
and	O
dicing	O
is	O
a	O
feature	O
whereby	O
users	O
can	O
take	O
out	O
(	O
slicing	O
)	O
a	O
specific	O
set	O
of	O
data	O
of	O
the	O
OLAP	B-Application
cube	O
and	O
view	O
(	O
dicing	O
)	O
the	O
slices	O
from	O
different	O
viewpoints	O
.	O
</s>
<s>
Databases	O
configured	O
for	O
OLAP	B-Application
use	O
a	O
multidimensional	B-Algorithm
data	I-Algorithm
model	O
,	O
allowing	O
for	O
complex	O
analytical	O
and	O
ad	O
hoc	O
queries	O
with	O
a	O
rapid	O
execution	O
time	O
.	O
</s>
<s>
They	O
borrow	O
aspects	O
of	O
navigational	B-General_Concept
databases	I-General_Concept
,	O
hierarchical	B-General_Concept
databases	I-General_Concept
and	O
relational	B-Application
databases	I-Application
.	O
</s>
<s>
OLAP	B-Application
is	O
typically	O
contrasted	O
to	O
OLTP	B-General_Concept
(	O
online	B-General_Concept
transaction	I-General_Concept
processing	I-General_Concept
)	O
,	O
which	O
is	O
generally	O
characterized	O
by	O
much	O
less	O
complex	O
queries	O
,	O
in	O
a	O
larger	O
volume	O
,	O
to	O
process	O
transactions	O
rather	O
than	O
for	O
the	O
purpose	O
of	O
business	B-General_Concept
intelligence	I-General_Concept
or	O
reporting	O
.	O
</s>
<s>
Whereas	O
OLAP	B-Application
systems	O
are	O
mostly	O
optimized	O
for	O
read	O
,	O
OLTP	B-General_Concept
has	O
to	O
process	O
all	O
kinds	O
of	O
queries	O
(	O
read	O
,	O
insert	O
,	O
update	O
and	O
delete	O
)	O
.	O
</s>
<s>
At	O
the	O
core	O
of	O
any	O
OLAP	B-Application
system	O
is	O
an	O
OLAP	B-Application
cube	O
(	O
also	O
called	O
a	O
'	O
multidimensional	O
cube	O
 '	O
or	O
a	O
hypercube	B-Operating_System
)	O
.	O
</s>
<s>
The	O
measures	O
are	O
placed	O
at	O
the	O
intersections	O
of	O
the	O
hypercube	B-Operating_System
,	O
which	O
is	O
spanned	O
by	O
the	O
dimensions	O
as	O
a	O
vector	O
space	O
.	O
</s>
<s>
The	O
usual	O
interface	O
to	O
manipulate	O
an	O
OLAP	B-Application
cube	O
is	O
a	O
matrix	O
interface	O
,	O
like	O
Pivot	B-Application
tables	I-Application
in	O
a	O
spreadsheet	O
program	O
,	O
which	O
performs	O
projection	O
operations	O
along	O
the	O
dimensions	O
,	O
such	O
as	O
aggregation	O
or	O
averaging	O
.	O
</s>
<s>
The	O
cube	O
metadata	O
is	O
typically	O
created	O
from	O
a	B-Protocol
star	I-Protocol
schema	O
or	O
snowflake	B-Language
schema	I-Language
or	O
fact	O
constellation	O
of	O
tables	O
in	O
a	O
relational	B-Application
database	I-Application
.	O
</s>
<s>
The	O
structure	O
is	O
broken	O
into	O
cubes	B-Library
and	O
the	O
cubes	B-Library
are	O
able	O
to	O
store	O
and	O
access	O
data	O
within	O
the	O
confines	O
of	O
each	O
cube	O
.	O
</s>
<s>
Multidimensional	O
structure	O
is	O
quite	O
popular	O
for	O
analytical	O
databases	O
that	O
use	O
online	B-Application
analytical	I-Application
processing	I-Application
(	O
OLAP	B-Application
)	O
applications	O
.	O
</s>
<s>
It	O
has	O
been	O
claimed	O
that	O
for	O
complex	O
queries	O
OLAP	B-Application
cubes	B-Library
can	O
produce	O
an	O
answer	O
in	O
around	O
0.1	O
%	O
of	O
the	O
time	O
required	O
for	O
the	O
same	O
query	O
on	O
OLTP	B-General_Concept
relational	O
data	O
.	O
</s>
<s>
The	O
most	O
important	O
mechanism	O
in	O
OLAP	B-Application
which	O
allows	O
it	O
to	O
achieve	O
such	O
performance	O
is	O
the	O
use	O
of	O
aggregations	O
.	O
</s>
<s>
The	O
objective	O
of	O
view	O
selection	O
is	O
typically	O
to	O
minimize	O
the	O
average	O
time	O
to	O
answer	O
OLAP	B-Application
queries	O
,	O
although	O
some	O
studies	O
also	O
minimize	O
the	O
update	O
time	O
.	O
</s>
<s>
Many	O
approaches	O
to	O
the	O
problem	O
have	O
been	O
explored	O
,	O
including	O
greedy	B-Algorithm
algorithms	I-Algorithm
,	O
randomized	O
search	O
,	O
genetic	B-Algorithm
algorithms	I-Algorithm
and	O
A*	B-Protocol
search	I-Protocol
algorithm	I-Protocol
.	O
</s>
<s>
Some	O
aggregation	O
functions	O
can	O
be	O
computed	O
for	O
the	O
entire	O
OLAP	B-Application
cube	O
by	O
precomputing	O
values	O
for	O
each	O
cell	O
,	O
and	O
then	O
computing	O
the	O
aggregation	O
for	O
a	O
roll-up	O
of	O
cells	O
by	O
aggregating	O
these	O
aggregates	O
,	O
applying	O
a	O
divide	B-Algorithm
and	I-Algorithm
conquer	I-Algorithm
algorithm	I-Algorithm
to	O
the	O
multidimensional	O
problem	O
to	O
compute	O
them	O
efficiently	O
.	O
</s>
<s>
Functions	O
that	O
can	O
be	O
decomposed	O
in	O
this	O
way	O
are	O
called	O
decomposable	B-Operating_System
aggregation	I-Operating_System
functions	I-Operating_System
,	O
and	O
include	O
COUNT	O
,	O
MAX	O
,	O
MIN	O
,	O
and	O
SUM	O
,	O
which	O
can	O
be	O
computed	O
for	O
each	O
cell	O
and	O
then	O
directly	O
aggregated	O
;	O
these	O
are	O
known	O
as	O
self-decomposable	O
aggregation	O
functions	O
.	O
</s>
<s>
These	O
latter	O
are	O
difficult	O
to	O
implement	O
efficiently	O
in	O
OLAP	B-Application
,	O
as	O
they	O
require	O
computing	O
the	O
aggregate	O
function	O
on	O
the	O
base	O
data	O
,	O
either	O
computing	O
them	O
online	O
(	O
slow	O
)	O
or	O
precomputing	O
them	O
for	O
possible	O
rollouts	O
(	O
large	O
space	O
)	O
.	O
</s>
<s>
OLAP	B-Application
systems	O
have	O
been	O
traditionally	O
categorized	O
using	O
the	O
following	O
taxonomy	O
.	O
</s>
<s>
MOLAP	O
(	O
multi-dimensional	O
online	B-Application
analytical	I-Application
processing	I-Application
)	O
is	O
the	O
classic	O
form	O
of	O
OLAP	B-Application
and	O
is	O
sometimes	O
referred	O
to	O
as	O
just	O
OLAP	B-Application
.	O
</s>
<s>
MOLAP	O
stores	O
this	O
data	O
in	O
an	O
optimized	O
multi-dimensional	O
array	O
storage	O
,	O
rather	O
than	O
in	O
a	O
relational	B-Application
database	I-Application
.	O
</s>
<s>
Such	O
MOLAP	O
tools	O
generally	O
utilize	O
a	O
pre-calculated	O
data	O
set	O
referred	O
to	O
as	O
a	O
data	B-Algorithm
cube	I-Algorithm
.	O
</s>
<s>
The	O
data	B-Algorithm
cube	I-Algorithm
contains	O
all	O
the	O
possible	O
answers	O
to	O
a	O
given	O
range	O
of	O
questions	O
.	O
</s>
<s>
Smaller	O
on-disk	O
size	O
of	O
data	O
compared	O
to	O
data	O
stored	O
in	O
relational	B-Application
database	I-Application
due	O
to	O
compression	B-General_Concept
techniques	I-General_Concept
.	O
</s>
<s>
Examples	O
of	O
commercial	O
products	O
that	O
use	O
MOLAP	O
are	O
Cognos	O
Powerplay	O
,	O
Oracle	B-Application
Database	I-Application
OLAP	I-Application
Option	I-Application
,	O
MicroStrategy	O
,	O
Microsoft	B-Application
Analysis	I-Application
Services	I-Application
,	O
Essbase	B-Application
,	O
TM1	O
,	O
Jedox	O
,	O
and	O
icCube	O
.	O
</s>
<s>
ROLAP	O
works	O
directly	O
with	O
relational	B-Application
databases	I-Application
and	O
does	O
not	O
require	O
pre-computation	O
.	O
</s>
<s>
This	O
methodology	O
relies	O
on	O
manipulating	O
the	O
data	O
stored	O
in	O
the	O
relational	B-Application
database	I-Application
to	O
give	O
the	O
appearance	O
of	O
traditional	O
OLAP	B-Application
's	O
slicing	O
and	O
dicing	O
functionality	O
.	O
</s>
<s>
In	O
essence	O
,	O
each	O
action	O
of	O
slicing	O
and	O
dicing	O
is	O
equivalent	O
to	O
adding	O
a	O
"	O
WHERE	O
"	O
clause	O
in	O
the	O
SQL	B-Language
statement	O
.	O
</s>
<s>
ROLAP	O
tools	O
do	O
not	O
use	O
pre-calculated	O
data	B-Algorithm
cubes	I-Algorithm
but	O
instead	O
pose	O
the	O
query	O
to	O
the	O
standard	O
relational	B-Application
database	I-Application
and	O
its	O
tables	O
in	O
order	O
to	O
bring	O
back	O
the	O
data	O
required	O
to	O
answer	O
the	O
question	O
.	O
</s>
<s>
While	O
ROLAP	O
uses	O
a	O
relational	B-Application
database	I-Application
source	O
,	O
generally	O
the	O
database	O
must	O
be	O
carefully	O
designed	O
for	O
ROLAP	O
use	O
.	O
</s>
<s>
A	O
database	O
which	O
was	O
designed	O
for	O
OLTP	B-General_Concept
will	O
not	O
function	O
well	O
as	O
a	O
ROLAP	O
database	O
.	O
</s>
<s>
ROLAP	O
is	O
considered	O
to	O
be	O
more	O
scalable	O
in	O
handling	O
large	O
data	O
volumes	O
,	O
especially	O
models	O
with	O
dimensions	O
with	O
very	O
high	O
cardinality	B-Application
(	O
i.e.	O
,	O
millions	O
of	O
members	O
)	O
.	O
</s>
<s>
The	O
data	O
are	O
stored	O
in	O
a	O
standard	O
relational	B-Application
database	I-Application
and	O
can	O
be	O
accessed	O
by	O
any	O
SQL	B-Language
reporting	O
tool	O
(	O
the	O
tool	O
does	O
not	O
have	O
to	O
be	O
an	O
OLAP	B-Application
tool	O
)	O
.	O
</s>
<s>
The	O
ROLAP	O
approach	O
can	O
leverage	O
database	O
authorization	O
controls	O
such	O
as	O
row-level	O
security	O
,	O
whereby	O
the	O
query	O
results	O
are	O
filtered	O
depending	O
on	O
preset	O
criteria	O
applied	O
,	O
for	O
example	O
,	O
to	O
a	O
given	O
user	O
or	O
group	O
of	O
users	O
(	O
SQL	B-Language
WHERE	O
clause	O
)	O
.	O
</s>
<s>
However	O
,	O
modern	O
ROLAP	O
tools	O
take	O
advantage	O
of	O
latest	O
improvements	O
in	O
SQL	B-Language
language	I-Language
such	O
as	O
CUBE	O
and	O
ROLLUP	O
operators	O
,	O
DB2	O
Cube	O
Views	O
,	O
as	O
well	O
as	O
other	O
SQL	B-Language
OLAP	B-Application
extensions	O
.	O
</s>
<s>
These	O
SQL	B-Language
improvements	O
can	O
mitigate	O
the	O
benefits	O
of	O
the	O
MOLAP	O
tools	O
.	O
</s>
<s>
Since	O
ROLAP	O
tools	O
rely	O
on	O
SQL	B-Language
for	O
all	O
of	O
the	O
computations	O
,	O
they	O
are	O
not	O
suitable	O
when	O
the	O
model	O
is	O
heavy	O
on	O
calculations	O
which	O
do	O
n't	O
translate	O
well	O
into	O
SQL	B-Language
.	O
</s>
<s>
In	O
the	O
OLAP	B-Application
industry	O
ROLAP	O
is	O
usually	O
perceived	O
as	O
being	O
able	O
to	O
scale	O
for	O
large	O
data	O
volumes	O
,	O
but	O
suffering	O
from	O
slower	O
query	O
performance	O
as	O
opposed	O
to	O
MOLAP	O
.	O
</s>
<s>
The	O
,	O
the	O
largest	O
independent	O
survey	O
across	O
all	O
major	O
OLAP	B-Application
products	O
,	O
being	O
conducted	O
for	O
6	O
years	O
(	O
2001	O
to	O
2006	O
)	O
have	O
consistently	O
found	O
that	O
companies	O
using	O
ROLAP	O
report	O
slower	O
performance	O
than	O
those	O
using	O
MOLAP	O
even	O
when	O
data	O
volumes	O
were	O
taken	O
into	O
consideration	O
.	O
</s>
<s>
Some	O
companies	O
select	O
ROLAP	O
because	O
they	O
intend	O
to	O
re-use	O
existing	O
relational	B-Application
database	I-Application
tables	O
—	O
these	O
tables	O
will	O
frequently	O
not	O
be	O
optimally	O
designed	O
for	O
OLAP	B-Application
use	O
.	O
</s>
<s>
MOLAP	O
tools	O
in	O
contrast	O
would	O
force	O
the	O
data	O
to	O
be	O
re-loaded	O
into	O
an	O
optimal	O
OLAP	B-Application
design	O
.	O
</s>
<s>
The	O
undesirable	O
trade-off	O
between	O
additional	O
ETL	O
cost	O
and	O
slow	O
query	O
performance	O
has	O
ensured	O
that	O
most	O
commercial	O
OLAP	B-Application
tools	O
now	O
use	O
a	O
"	O
Hybrid	O
OLAP	B-Application
"	O
(	O
HOLAP	O
)	O
approach	O
,	O
which	O
allows	O
the	O
model	O
designer	O
to	O
decide	O
which	O
portion	O
of	O
the	O
data	O
will	O
be	O
stored	O
in	O
MOLAP	O
and	O
which	O
portion	O
in	O
ROLAP	O
.	O
</s>
<s>
There	O
is	O
no	O
clear	O
agreement	O
across	O
the	O
industry	O
as	O
to	O
what	O
constitutes	O
"	O
Hybrid	O
OLAP	B-Application
"	O
,	O
except	O
that	O
a	O
database	O
will	O
divide	O
data	O
between	O
relational	O
and	O
specialized	O
storage	O
.	O
</s>
<s>
HOLAP	O
tools	O
can	O
utilize	O
both	O
pre-calculated	O
cubes	B-Library
and	O
relational	O
data	O
sources	O
.	O
</s>
<s>
The	O
first	O
product	O
to	O
provide	O
HOLAP	O
storage	O
was	O
Holos	O
,	O
but	O
the	O
technology	O
also	O
became	O
available	O
in	O
other	O
commercial	O
products	O
such	O
as	O
Microsoft	B-Application
Analysis	I-Application
Services	I-Application
,	O
Oracle	B-Application
Database	I-Application
OLAP	I-Application
Option	I-Application
,	O
MicroStrategy	O
and	O
SAP	B-Application
AG	I-Application
BI	O
Accelerator	O
.	O
</s>
<s>
The	O
hybrid	O
OLAP	B-Application
approach	O
combines	O
ROLAP	O
and	O
MOLAP	O
technology	O
,	O
benefiting	O
from	O
the	O
greater	O
scalability	O
of	O
ROLAP	O
and	O
the	O
faster	O
computation	O
of	O
MOLAP	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
HOLAP	O
server	O
may	O
store	O
large	O
volumes	O
of	O
detailed	O
data	O
in	O
a	O
relational	B-Application
database	I-Application
,	O
while	O
aggregations	O
are	O
kept	O
in	O
a	O
separate	O
MOLAP	O
store	O
.	O
</s>
<s>
Some	O
MOLAP	O
implementations	O
are	O
prone	O
to	O
database	O
explosion	O
,	O
a	O
phenomenon	O
causing	O
vast	O
amounts	O
of	O
storage	O
space	O
to	O
be	O
used	O
by	O
MOLAP	O
databases	O
when	O
certain	O
common	O
conditions	O
are	O
met	O
:	O
high	O
number	O
of	O
dimensions	O
,	O
pre-calculated	O
results	O
and	O
sparse	O
multidimensional	B-Algorithm
data	I-Algorithm
.	O
</s>
<s>
MOLAP	O
also	O
needs	O
less	O
storage	O
space	O
compared	O
to	O
ROLAP	O
because	O
the	O
specialized	O
storage	O
typically	O
includes	O
compression	B-General_Concept
techniques	I-General_Concept
.	O
</s>
<s>
CaseOLAP	O
–	O
Context-aware	O
Semantic	O
OLAP	B-Application
,	O
developed	O
for	O
biomedical	O
applications	O
.	O
</s>
<s>
Unlike	O
relational	B-Application
databases	I-Application
,	O
which	O
had	O
SQL	B-Language
as	O
the	O
standard	O
query	O
language	O
,	O
and	O
widespread	O
APIs	B-Application
such	O
as	O
ODBC	B-Application
,	O
JDBC	B-Language
and	O
OLEDB	B-Language
,	O
there	O
was	O
no	O
such	O
unification	O
in	O
the	O
OLAP	B-Application
world	O
for	O
a	O
long	O
time	O
.	O
</s>
<s>
The	O
first	O
real	O
standard	O
API	B-Application
was	O
OLE	B-Language
DB	I-Language
for	O
OLAP	B-Application
specification	O
from	O
Microsoft	O
which	O
appeared	O
in	O
1997	O
and	O
introduced	O
the	O
MDX	B-Language
query	O
language	O
.	O
</s>
<s>
Several	O
OLAP	B-Application
vendors	O
–	O
both	O
server	O
and	O
client	O
–	O
adopted	O
it	O
.	O
</s>
<s>
In	O
2001	O
Microsoft	O
and	O
Hyperion	O
announced	O
the	O
XML	O
for	O
Analysis	O
specification	O
,	O
which	O
was	O
endorsed	O
by	O
most	O
of	O
the	O
OLAP	B-Application
vendors	O
.	O
</s>
<s>
Since	O
this	O
also	O
used	O
MDX	B-Language
as	O
a	O
query	O
language	O
,	O
MDX	B-Language
became	O
the	O
de	O
facto	O
standard	O
.	O
</s>
<s>
Since	O
September-2011	O
LINQ	B-Language
can	O
be	O
used	O
to	O
query	O
SSAS	B-Application
OLAP	B-Application
cubes	B-Library
from	O
Microsoft	O
.NET	O
.	O
</s>
<s>
The	O
first	O
product	O
that	O
performed	O
OLAP	B-Application
queries	O
was	O
Express	O
,	O
which	O
was	O
released	O
in	O
1970	O
(	O
and	O
acquired	O
by	O
Oracle	B-Application
in	O
1995	O
from	O
Information	O
Resources	O
)	O
.	O
</s>
<s>
However	O
,	O
the	O
term	O
did	O
not	O
appear	O
until	O
1993	O
when	O
it	O
was	O
coined	O
by	O
Edgar	O
F	O
.	O
Codd	O
,	O
who	O
has	O
been	O
described	O
as	O
"	O
the	O
father	O
of	O
the	O
relational	B-Application
database	I-Application
"	O
.	O
</s>
<s>
Codd	O
's	O
paper	O
resulted	O
from	O
a	O
short	O
consulting	O
assignment	O
which	O
Codd	O
undertook	O
for	O
former	O
Arbor	O
Software	O
(	O
later	O
Hyperion	O
Solutions	O
,	O
and	O
in	O
2007	O
acquired	O
by	O
Oracle	B-Application
)	O
,	O
as	O
a	O
sort	O
of	O
marketing	O
coup	O
.	O
</s>
<s>
The	O
company	O
had	O
released	O
its	O
own	O
OLAP	B-Application
product	O
,	O
Essbase	B-Application
,	O
a	O
year	O
earlier	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
Codd	O
's	O
"	O
twelve	O
laws	O
of	O
online	B-Application
analytical	I-Application
processing	I-Application
"	O
were	O
explicit	O
in	O
their	O
reference	O
to	O
Essbase	B-Application
.	O
</s>
<s>
The	O
OLAP	B-Application
market	O
experienced	O
strong	O
growth	O
in	O
the	O
late	O
1990s	O
with	O
dozens	O
of	O
commercial	O
products	O
going	O
into	O
market	O
.	O
</s>
<s>
In	O
1998	O
,	O
Microsoft	O
released	O
its	O
first	O
OLAP	B-Application
Server	O
Microsoft	B-Application
Analysis	I-Application
Services	I-Application
,	O
which	O
drove	O
wide	O
adoption	O
of	O
OLAP	B-Application
technology	O
and	O
moved	O
it	O
into	O
the	O
mainstream	O
.	O
</s>
<s>
OLAP	B-Application
clients	O
include	O
many	O
spreadsheet	O
programs	O
like	O
Excel	O
,	O
web	O
application	O
,	O
SQL	B-Language
,	O
dashboard	O
tools	O
,	O
etc	O
.	O
</s>
<s>
Some	O
dimensions	O
are	O
used	O
as	O
filters	O
(	O
for	O
slicing	O
and	O
dicing	O
the	O
data	O
)	O
while	O
others	O
are	O
selected	O
as	O
the	O
axes	O
of	O
a	O
pivot	B-Application
table	I-Application
or	O
pivot	B-Application
chart	I-Application
.	O
</s>
<s>
An	O
extensive	O
list	O
of	O
clients	O
appears	O
in	O
the	O
visualization	O
column	O
of	O
the	O
comparison	O
of	O
OLAP	B-Application
servers	O
table	O
.	O
</s>
<s>
Below	O
is	O
a	O
list	O
of	O
top	O
OLAP	B-Application
vendors	O
in	O
2006	O
,	O
with	O
figures	O
in	O
millions	O
of	O
US	O
Dollars	O
.	O
</s>
<s>
Apache	B-Application
Pinot	I-Application
is	O
used	O
at	O
LinkedIn	O
,	O
Cisco	O
,	O
Uber	O
,	O
Slack	O
,	O
Stripe	O
,	O
DoorDash	O
,	O
Target	O
,	O
Walmart	O
,	O
Amazon	O
,	O
and	O
Microsoft	O
to	O
deliver	O
scalable	O
real	O
time	O
analytics	O
with	O
low	O
latency	O
.	O
</s>
<s>
Pinot	B-Application
is	O
designed	O
to	O
scale	O
horizontally	O
.	O
</s>
<s>
Mondrian	B-Application
OLAP	I-Application
server	I-Application
is	O
an	O
open-source	B-Application
OLAP	B-Application
server	O
written	O
in	O
Java	B-Language
.	O
</s>
<s>
It	O
supports	O
the	O
MDX	B-Language
query	O
language	O
,	O
the	O
XML	O
for	O
Analysis	O
and	O
the	O
interface	O
specifications	O
.	O
</s>
<s>
Apache	B-Application
Druid	I-Application
is	O
a	O
popular	O
open-source	B-Application
distributed	O
data	O
store	O
for	O
OLAP	B-Application
queries	O
that	O
is	O
used	O
at	O
scale	O
in	O
production	O
by	O
various	O
organizations	O
.	O
</s>
<s>
Apache	B-Application
Kylin	I-Application
is	O
a	O
distributed	O
data	O
store	O
for	O
OLAP	B-Application
queries	O
originally	O
developed	O
by	O
eBay	O
.	O
</s>
<s>
Cubes	B-Library
(	O
OLAP	B-Application
server	O
)	O
is	O
another	O
light-weight	O
open-source	B-Application
toolkit	O
implementation	O
of	O
OLAP	B-Application
functionality	O
in	O
the	O
Python	B-Language
programming	I-Language
language	I-Language
with	O
built-in	O
ROLAP	O
.	O
</s>
<s>
ClickHouse	B-Language
is	O
a	O
fairly	O
new	O
column	O
orientated	O
DBMS	O
focusing	O
on	O
fast	O
processing	O
and	O
response	O
times	O
.	O
</s>
<s>
Duckdb	O
is	O
an	O
in-process	O
SQL	B-Language
OLAP	B-Application
database	O
management	O
system	O
.	O
</s>
