<s>
GQL	B-Language
(	O
Graph	B-Language
Query	I-Language
Language	I-Language
)	O
is	O
a	O
proposed	O
standard	O
graph	B-Language
query	I-Language
language	I-Language
.	O
</s>
<s>
In	O
September	O
2019	O
a	O
proposal	O
for	O
a	O
project	O
to	O
create	O
a	O
new	O
standard	O
graph	B-Language
query	I-Language
language	I-Language
(	O
ISO/IEC	O
39075	O
Information	O
Technology	O
—	O
Database	O
Languages	O
—	O
GQL	B-Language
)	O
was	O
approved	O
by	O
a	O
vote	O
of	O
national	O
standards	O
bodies	O
which	O
are	O
members	O
of	O
ISO/IEC	O
Joint	O
Technical	O
Committee	O
1( )	O
.	O
</s>
<s>
GQL	B-Language
is	O
intended	O
to	O
be	O
a	O
declarative	O
database	B-Language
query	I-Language
language	I-Language
,	O
like	O
SQL	B-Language
.	O
</s>
<s>
The	O
GQL	B-Language
project	O
proposal	O
states	O
:	O
</s>
<s>
The	O
GQL	B-Language
project	O
is	O
the	O
culmination	O
of	O
converging	O
initiatives	O
dating	O
back	O
to	O
2016	O
,	O
particularly	O
a	O
private	O
proposal	O
from	O
Neo4j	B-Language
to	O
other	O
database	O
vendors	O
in	O
July	O
2016	O
,	O
and	O
a	O
proposal	O
from	O
Oracle	O
technical	O
staff	O
within	O
the	O
ISO/IEC	O
JTC	O
1	O
standards	O
process	O
later	O
that	O
year	O
.	O
</s>
<s>
The	O
GQL	B-Language
project	O
is	O
led	O
by	O
Stefan	O
Plantikow	O
(	O
who	O
was	O
the	O
first	O
lead	O
engineer	O
of	O
Neo4j	B-Language
's	O
Cypher	B-Language
for	O
Apache	B-Language
Spark	I-Language
project	O
)	O
and	O
Stephen	O
Cannan	O
(	O
Technical	O
Corrigenda	O
editor	O
of	O
SQL	B-Language
)	O
.	O
</s>
<s>
They	O
are	O
also	O
the	O
editors	O
of	O
the	O
initial	O
early	O
working	O
drafts	O
of	O
the	O
GQL	B-Language
specification	O
.	O
</s>
<s>
As	O
originally	O
motivated	O
,	O
the	O
GQL	B-Language
project	O
aims	O
to	O
complement	O
the	O
work	O
of	O
creating	O
an	O
implementable	O
normative	O
natural-language	O
specification	O
with	O
supportive	O
community	O
efforts	O
that	O
enable	O
contributions	O
from	O
those	O
who	O
are	O
unable	O
or	O
uninterested	O
in	O
taking	O
part	O
in	O
the	O
formal	O
process	O
of	O
defining	O
a	O
JTC	O
1	O
International	O
Standard	O
.	O
</s>
<s>
A	O
working	O
group	O
to	O
define	O
formal	O
denotational	B-Application
semantics	I-Application
for	O
GQL	B-Language
was	O
proposed	O
at	O
the	O
third	O
GQL	B-Language
Community	O
Update	O
in	O
October	O
2019	O
.	O
</s>
<s>
GQL	B-Language
is	O
a	O
query	B-Language
language	I-Language
specifically	O
for	O
property	O
graphs	O
.	O
</s>
<s>
A	O
property	O
graph	O
closely	O
resembles	O
a	O
conceptual	O
data	O
model	O
,	O
as	O
expressed	O
in	O
an	O
entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
model	I-Architecture
or	O
in	O
a	O
UML	B-Language
class	O
diagram	O
(	O
although	O
it	O
does	O
not	O
include	O
n-ary	O
relationships	O
linking	O
more	O
than	O
two	O
entities	O
)	O
.	O
</s>
<s>
GQL	B-Language
graphs	O
can	O
be	O
mixed	O
:	O
they	O
can	O
contain	O
directed	O
edges	O
,	O
where	O
one	O
of	O
the	O
endpoint	O
nodes	O
of	O
an	O
edge	O
is	O
the	O
tail	O
(	O
or	O
source	O
)	O
and	O
the	O
other	O
node	O
is	O
the	O
head	O
(	O
or	O
target	O
or	O
destination	O
)	O
,	O
but	O
they	O
can	O
also	O
contain	O
undirected	O
(	O
bidirectional	O
or	O
reflexive	O
)	O
edges	O
.	O
</s>
<s>
Current	O
graph	B-Application
database	I-Application
products	O
and	O
projects	O
often	O
support	O
a	O
limited	O
version	O
of	O
the	O
model	O
described	O
here	O
.	O
</s>
<s>
For	O
example	O
,	O
Apache	O
Tinkerpop	O
forces	O
each	O
node	O
and	O
each	O
edge	O
to	O
have	O
a	O
single	O
label	O
;	O
Cypher	B-Language
allows	O
nodes	O
to	O
have	O
zero	O
to	O
many	O
labels	O
,	O
but	O
relationships	O
only	O
have	O
a	O
single	O
label	O
(	O
called	O
a	O
reltype	O
)	O
.	O
</s>
<s>
Neo4j	B-Language
's	O
database	O
supports	O
undocumented	O
graph-wide	O
properties	O
,	O
Tinkerpop	O
has	O
graph	O
values	O
which	O
play	O
the	O
same	O
role	O
,	O
and	O
also	O
supports	O
"	O
metaproperties	O
"	O
or	O
properties	O
on	O
properties	O
.	O
</s>
<s>
Oracle	O
's	O
PGQL	O
supports	O
zero	O
to	O
many	O
labels	O
on	O
nodes	O
and	O
on	O
edges	O
,	O
whereas	O
SQL/PGQ	O
supports	O
one	O
to	O
many	O
labels	O
for	O
each	O
kind	O
of	O
element	O
.	O
</s>
<s>
The	O
GQL	B-Language
project	O
will	O
define	O
a	O
standard	O
data	O
model	O
,	O
which	O
is	O
likely	O
to	O
be	O
the	O
superset	O
of	O
these	O
variants	O
,	O
and	O
at	O
least	O
the	O
first	O
version	O
of	O
GQL	B-Language
is	O
likely	O
to	O
permit	O
vendors	O
to	O
decide	O
on	O
the	O
cardinalities	O
of	O
labels	O
in	O
each	O
implementation	O
,	O
as	O
does	O
SQL/PGQ	O
,	O
and	O
to	O
choose	O
whether	O
to	O
support	O
undirected	O
relationships	O
.	O
</s>
<s>
Additional	O
aspects	O
of	O
the	O
ERM	O
or	O
UML	B-Language
models	O
(	O
like	O
generalization	O
or	O
subtyping	O
,	O
or	O
entity	O
or	O
relationship	O
cardinalities	O
)	O
may	O
be	O
captured	O
by	O
GQL	B-Language
schemas	O
or	O
types	O
that	O
describe	O
possible	O
instances	O
of	O
the	O
general	O
data	O
model	O
.	O
</s>
<s>
Although	O
the	O
GQL	B-Language
Standard	O
is	O
not	O
yet	O
publicly	O
available	O
,	O
the	O
first	O
in-memory	O
graph	B-Application
database	I-Application
that	O
can	O
interpret	O
GQL	B-Language
is	O
available	O
.	O
</s>
<s>
Aside	O
from	O
the	O
implementation	O
,	O
one	O
can	O
also	O
find	O
a	O
formalization	O
and	O
read	O
the	O
syntax	O
of	O
the	O
specific	O
subset	O
of	O
GQL	B-Language
.	O
</s>
<s>
The	O
GQL	B-Language
project	O
has	O
a	O
four-year	O
time	O
span	O
.	O
</s>
<s>
WG3	O
(	O
and	O
its	O
direct	O
predecessor	O
committees	O
within	O
JTC	O
1	O
)	O
has	O
been	O
responsible	O
for	O
the	O
SQL	B-Language
standard	O
since	O
1987	O
.	O
</s>
<s>
The	O
GQL	B-Language
project	O
draws	O
on	O
multiple	O
sources	O
or	O
inputs	O
,	O
notably	O
existing	O
industrial	O
languages	O
and	O
a	O
new	O
section	O
of	O
the	O
SQL	B-Language
standard	O
.	O
</s>
<s>
GQL	B-Language
will	O
be	O
a	O
declarative	O
language	O
with	O
its	O
own	O
distinct	O
syntax	O
,	O
playing	O
a	O
similar	O
role	O
to	O
SQL	B-Language
in	O
the	O
building	O
of	O
a	O
database	O
application	O
.	O
</s>
<s>
Other	O
graph	B-Language
query	I-Language
languages	I-Language
have	O
been	O
defined	O
which	O
offer	O
direct	O
procedural	O
features	O
such	O
as	O
branching	O
and	O
looping	O
(	O
Apache	O
Tinkerpop	O
's	O
Gremlin	O
,	O
)	O
,	O
and	O
GSQL	O
,	O
making	O
it	O
possible	O
to	O
traverse	O
a	O
graph	O
iteratively	O
to	O
perform	O
a	O
class	O
of	O
graph	O
algorithms	O
,	O
but	O
GQL	B-Language
will	O
not	O
directly	O
incorporate	O
such	O
features	O
.	O
</s>
<s>
However	O
,	O
GQL	B-Language
is	O
envisaged	O
as	O
a	O
specific	O
case	O
of	O
a	O
more	O
general	O
class	O
of	O
graph	O
languages	O
,	O
which	O
will	O
share	O
a	O
graph	O
type	O
system	O
and	O
a	O
calling	O
interface	O
for	O
procedures	O
that	O
process	O
graphs	O
.	O
</s>
<s>
Prior	O
work	O
by	O
WG3	O
and	O
SC32	O
mirror	O
bodies	O
,	O
particularly	O
in	O
INCITS	O
DM32	O
,	O
has	O
helped	O
to	O
define	O
a	O
new	O
planned	O
Part	O
16	O
of	O
the	O
SQL	B-Language
Standard	O
,	O
which	O
allows	O
a	O
read-only	O
graph	O
query	O
to	O
be	O
called	O
inside	O
a	O
SQL	B-Language
SELECT	O
statement	O
,	O
matching	O
a	O
graph	O
pattern	O
using	O
syntax	O
which	O
is	O
very	O
close	O
to	O
Cypher	B-Language
,	O
PGQL	O
and	O
G-CORE	O
,	O
and	O
returning	O
a	O
table	O
of	O
data	O
values	O
as	O
the	O
result	O
.	O
</s>
<s>
SQL/PGQ	O
also	O
contains	O
DDL	O
to	O
allow	O
SQL	B-Language
tables	O
to	O
be	O
mapped	O
to	O
a	O
graph	O
view	O
schema	O
object	O
with	O
nodes	O
and	O
edges	O
associated	O
to	O
sets	O
of	O
labels	O
and	O
set	O
of	O
data	O
properties	O
.	O
</s>
<s>
The	O
GQL	B-Language
project	O
coordinates	O
closely	O
with	O
the	O
SQL/PGQ	O
"	O
project	O
split	O
"	O
of	O
(	O
extension	O
to	O
)	O
ISO	O
9075	O
SQL	B-Language
,	O
and	O
the	O
technical	O
working	O
groups	O
in	O
the	O
U.S.	O
(	O
INCITS	O
DM32	O
)	O
and	O
at	O
the	O
international	O
level	O
(	O
SC32/WG3	O
)	O
have	O
several	O
expert	O
contributors	O
who	O
work	O
on	O
both	O
projects	O
.	O
</s>
<s>
The	O
GQL	B-Language
project	O
proposal	O
mandates	O
close	O
alignment	O
of	O
SQL/PGQ	O
and	O
GQL	B-Language
,	O
indicating	O
that	O
GQL	B-Language
will	O
in	O
general	O
be	O
a	O
superset	O
of	O
SQL/PGQ	O
.	O
</s>
<s>
Cypher	B-Language
is	O
a	O
language	O
originally	O
designed	O
by	O
Andrés	O
Taylor	O
and	O
colleagues	O
at	O
Neo4j	B-Language
Inc.	O
,	O
and	O
first	O
implemented	O
by	O
that	O
company	O
in	O
2011	O
.	O
</s>
<s>
Since	O
2015	O
it	O
has	O
been	O
made	O
available	O
as	O
an	O
open	O
source	O
language	O
description	O
with	O
grammar	O
tooling	O
,	O
a	O
JVM	B-Language
front-end	O
that	O
parses	O
Cypher	B-Language
queries	O
,	O
and	O
a	O
Technology	O
Compatibility	O
Kit	O
(	O
TCK	O
)	O
of	O
over	O
2000	O
test	O
scenarios	O
,	O
using	O
Cucumber	B-Application
for	O
implementation	O
language	O
portability	O
.	O
</s>
<s>
The	O
TCK	O
reflects	O
the	O
language	O
description	O
and	O
an	O
enhancement	O
for	O
temporal	O
datatypes	O
and	O
functions	O
documented	O
in	O
a	O
Cypher	B-Language
Improvement	O
Proposal	O
.	O
</s>
<s>
Cypher	B-Language
allows	O
creation	O
,	O
reading	O
,	O
updating	O
and	O
deleting	O
of	O
graph	O
elements	O
,	O
and	O
is	O
a	O
language	O
that	O
can	O
therefore	O
be	O
used	O
for	O
analytics	O
engines	O
and	O
transactional	O
databases	O
.	O
</s>
<s>
Cypher	B-Language
uses	O
compact	O
fixed	O
-	O
and	O
variable-length	O
patterns	O
which	O
combine	O
visual	O
representations	O
of	O
node	O
and	O
relationship	O
(	O
edge	O
)	O
topologies	O
,	O
with	O
label	O
existence	O
and	O
property	O
value	O
predicates	O
.	O
</s>
<s>
Following	O
the	O
lead	O
of	O
G-CORE	O
and	O
Morpheus	O
,	O
GQL	B-Language
aims	O
to	O
project	O
the	O
sub-graphs	O
defined	O
by	O
matching	O
patterns	O
(	O
and	O
graphs	O
then	O
computed	O
over	O
those	O
sub-graphs	O
)	O
as	O
new	O
graphs	O
to	O
be	O
returned	O
by	O
a	O
query	O
.	O
</s>
<s>
Patterns	O
of	O
this	O
kind	O
have	O
become	O
pervasive	O
in	O
property	O
graph	B-Language
query	I-Language
languages	I-Language
,	O
and	O
are	O
the	O
basis	O
for	O
the	O
advanced	O
pattern	O
sub-language	O
being	O
defined	O
in	O
SQL/PGQ	O
,	O
which	O
is	O
likely	O
to	O
become	O
a	O
subset	O
of	O
the	O
GQL	B-Language
language	O
.	O
</s>
<s>
Cypher	B-Language
also	O
uses	O
patterns	O
for	O
insertion	O
and	O
modification	O
clauses	O
(	O
and	O
)	O
,	O
and	O
proposals	O
have	O
been	O
made	O
in	O
the	O
GQL	B-Language
project	O
for	O
collecting	O
node	O
and	O
edge	O
patterns	O
to	O
describe	O
graph	O
types	O
.	O
</s>
<s>
The	O
current	O
version	O
of	O
Cypher	B-Language
(	O
including	O
the	O
temporal	O
extension	O
)	O
is	O
referred	O
to	O
as	O
Cypher	B-Language
9	O
.	O
</s>
<s>
Prior	O
to	O
the	O
GQL	B-Language
project	O
it	O
was	O
planned	O
to	O
create	O
a	O
new	O
version	O
,	O
Cypher	B-Language
10	O
[	O
REF	O
HEADING	O
BELOW ]	O
,	O
that	O
would	O
incorporate	O
features	O
like	O
schema	O
and	O
composable	O
graph	O
queries	O
and	O
views	O
.	O
</s>
<s>
The	O
first	O
designs	O
for	O
Cypher	B-Language
10	O
,	O
including	O
graph	O
construction	O
and	O
projection	O
,	O
were	O
implemented	O
in	O
the	O
Cypher	B-Language
for	O
Apache	B-Language
Spark	I-Language
project	O
starting	O
in	O
2016	O
.	O
</s>
<s>
is	O
a	O
language	O
designed	O
and	O
implemented	O
by	O
Oracle	O
Inc.	O
,	O
but	O
made	O
available	O
as	O
an	O
open	O
source	O
specification	O
,	O
along	O
with	O
JVM	B-Language
parsing	O
software	O
.	O
</s>
<s>
PGQL	O
combines	O
familiar	O
SQL	B-Language
SELECT	O
syntax	O
including	O
SQL	B-Language
expressions	O
and	O
result	O
ordering	O
and	O
aggregation	O
with	O
a	O
pattern	O
matching	O
language	O
very	O
similar	O
to	O
that	O
of	O
Cypher	B-Language
.	O
</s>
<s>
G-CORE	O
is	O
a	O
research	O
language	O
designed	O
by	O
a	O
group	O
of	O
academic	O
and	O
industrial	O
researchers	O
and	O
language	O
designers	O
which	O
draws	O
on	O
features	O
of	O
Cypher	B-Language
,	O
PGQL	O
and	O
SPARQL	B-Language
.	O
</s>
<s>
The	O
project	O
was	O
conducted	O
under	O
the	O
auspices	O
of	O
the	O
Linked	O
Data	O
Benchmark	O
Council	O
(	O
LDBC	O
)	O
,	O
starting	O
with	O
the	O
formation	O
of	O
a	O
Graph	B-Language
Query	I-Language
Language	I-Language
task	O
force	O
in	O
late	O
2015	O
,	O
with	O
the	O
bulk	O
of	O
the	O
work	O
of	O
paper	O
writing	O
occurring	O
in	O
2017	O
.	O
</s>
<s>
G-CORE	O
has	O
been	O
partially	O
implemented	O
in	O
open-source	O
research	O
projects	O
in	O
the	O
LDBC	O
GitHub	B-Application
organization	O
.	O
</s>
<s>
GSQL	O
is	O
a	O
language	O
designed	O
for	O
TigerGraph	O
Inc.	O
'	O
s	O
proprietary	O
graph	B-Application
database	I-Application
.	O
</s>
<s>
Since	O
October	O
2018	O
TigerGraph	O
language	O
designers	O
have	O
been	O
promoting	O
and	O
working	O
on	O
the	O
GQL	B-Language
project	O
.	O
</s>
<s>
This	O
schema	O
therefore	O
has	O
the	O
closed	O
world	O
property	O
of	O
an	O
SQL	B-Language
schema	O
,	O
and	O
this	O
aspect	O
of	O
GSQL	O
(	O
also	O
reflected	O
in	O
design	O
proposals	O
deriving	O
from	O
the	O
Morpheus	O
project	O
)	O
is	O
proposed	O
as	O
an	O
important	O
optional	O
feature	O
of	O
GQL	B-Language
.	O
</s>
<s>
Vertexes	O
and	O
edges	O
are	O
named	O
schema	O
objects	O
which	O
contain	O
data	O
but	O
also	O
define	O
an	O
imputed	O
type	O
,	O
much	O
as	O
SQL	B-Language
tables	O
are	O
data	O
containers	O
,	O
with	O
an	O
associated	O
implicit	O
row	O
type	O
.	O
</s>
<s>
The	O
opencypher	O
Morpheus	O
project	O
implements	O
Cypher	B-Language
for	O
Apache	B-Language
Spark	I-Language
users	O
.	O
</s>
<s>
Commencing	O
in	O
2016	O
,	O
this	O
project	O
originally	O
ran	O
alongside	O
three	O
related	O
efforts	O
,	O
in	O
which	O
Morpheus	O
designers	O
also	O
took	O
part	O
:	O
SQL/PGQ	O
,	O
G-CORE	O
and	O
design	O
of	O
Cypher	B-Language
extensions	O
for	O
querying	O
and	O
constructing	O
multiple	O
graphs	O
.	O
</s>
<s>
The	O
Morpheus	O
project	O
acted	O
as	O
a	O
testbed	O
for	O
extensions	O
to	O
Cypher	B-Language
(	O
known	O
as	O
"	O
Cypher	B-Language
10	O
"	O
)	O
in	O
the	O
two	O
areas	O
of	O
graph	O
DDL	O
and	O
query	B-Language
language	I-Language
extensions	O
.	O
</s>
<s>
These	O
features	O
have	O
been	O
proposed	O
as	O
inputs	O
to	O
the	O
standardization	O
of	O
property	O
graph	B-Language
query	I-Language
languages	I-Language
in	O
the	O
GQL	B-Language
project	O
.	O
</s>
