Graph Querying Language¶

A query to the graph is composed of two distinct parts:

the walk through part, used to walk through the graph and select sets of elements

the operations part, used to execute operations on the selected sets

Walk through¶

A walk-through is composed of:

FROM statements, used to define sets of nodes

THROUGH statements, used to walk through aliased relations

TO statements, used to alias the destination nodes

The first FROM statement is used to selects elements from the graph, creating a sub-graph:

FROM <set> <node filter> [ AS <alias> ]

THROUGH <set> <relation filter> [ AS <alias> ] [ <walk mode> ]

TO <node filter> <alias>

A second FROM statements will select another sub-graph, from the alias created by the previous statement.

FROM NODES () {} AS nodes0
FROM nodes0 (n1 n2) { foo = "bar" } AS nodes1
FROM nodes1 (n1) { bar = "baz" AND baz = "biz" } AS nodes2

THROUGH
    RELS () {} AS rels0
    DEPTH BACKWARD 5 10
THROUGH
    rels0 (r1 r2) { weight > 2 } AS rels1
    BREADTH FORWARD 2 *
THROUGH
    rels1 (r1) {}

TO
    (n3) {}
    nodes3

TO
    (n4) {}
    nodes4

Operations¶

There is 4 types of operations:

SELECT used to fetch aliased elements

INSERT used to create new elements (may be aliased)

UPDATE used to update aliased elements

DELETE used to delete aliased elements

Read operations¶

A SELECT statement expects a list of alias to be returned

SELECT alias1, alias2, alias3

Create operations¶

An INSERT statement expects one of two kinds of element definition that can be aliased for further use:

node definition

relationship definition, which expects a set of source nodes and a set of target nodes

INSERT
    NODE(<new node types>) { <new node assignations> } AS alias0

INSERT
    REL(<new relationship types) { <new relationship assignations> }

    SOURCE
        <alias or node filter>
    TARGET
        <alias or node filter>

For example:

INSERT
    NODE(n2) {
        ADDTOSET foo "bar"
    } AS elt18
INSERT
    REL(r3) {
        SET weight 2
    }
    SOURCE
        (n4) { foo = "buzz" }
    TARGET
        elt18

Update operations¶

An UPDATE statement expects a set of new assignations on aliased properties:

UPDATE ( <assignations> )

For example:

UPDATE (
    SET alias2.weight 17
    ADDTOSET alias0.bar "baz"
    UNSET alias1.foo
    DELFROMSET alias0.bar "biz"
)

Delete operations¶

A DELETE statement have exactly the same syntax as a SELECT statement:

DELETE alias1, alias2, alias3