<s>
Apache	B-Language
Calcite	I-Language
is	O
an	O
open	B-Application
source	I-Application
framework	O
for	O
building	O
databases	O
and	O
data	O
management	O
systems	O
.	O
</s>
<s>
It	O
includes	O
a	O
SQL	B-Language
parser	B-Language
,	O
an	O
API	B-General_Concept
for	O
building	O
expressions	O
in	O
relational	B-Algorithm
algebra	I-Algorithm
,	O
and	O
a	O
query	B-Language
planning	I-Language
engine	O
.	O
</s>
<s>
As	O
a	O
framework	O
,	O
Calcite	O
does	O
not	O
store	O
its	O
own	O
data	O
or	O
metadata	O
,	O
but	O
instead	O
allows	O
external	O
data	O
and	O
metadata	O
to	O
be	O
accessed	O
by	O
means	O
of	O
plug-ins	B-Application
.	O
</s>
<s>
Hive	B-General_Concept
uses	O
Calcite	O
for	O
cost-based	O
query	B-Language
optimization	I-Language
;	O
</s>
<s>
Drill	B-General_Concept
and	O
Kylin	B-Application
use	O
Calcite	O
for	O
SQL	B-Language
parsing	O
and	O
optimization	O
;	O
</s>
<s>
Samza	B-Application
and	O
Storm	B-General_Concept
use	O
Calcite	O
for	O
streaming	O
SQL	B-Language
.	O
</s>
<s>
,	O
Apex	B-Application
,	O
Phoenix	B-Application
and	O
Flink	B-Application
have	O
projects	O
under	O
development	O
that	O
use	O
Calcite	O
.	O
</s>
