1.MetaQL Overview
1.1.Overview
- Overview goes here
2.Select Queries
Example:
SELECT {
value limit: 100
value offset: 0
value segments: ["mydata"]
constraint { Person.class }
constraint { Person.props().name.equalTo("John" ) }
}The results are returned in a ResultList containing GraphObjects.
3.Graph Queries
Example:
Given a set of Email messages with links to senders and receivers, find all messages sent by “john@example.org“, excluding those he sent to himself.
GRAPH {
value segments: ["mydata"]
ARC {
node_constraint { Email.class }
constraint { "?person1 != ?person2" }
ARC_AND {
ARC {
edge_constraint { Edge_hasSender.class }
node_constraint {Person.props().emailAddress.equalTo("john@example.org")
node_constraint { Person.class }
node_provides { "person1 = URI" }
}
ARC {
edge_constraint { Edge_hasRecipient.class }
node_constraint { Person.class }
node_provides { "person2 = URI" }
}
}
}
}The results are returned in a ResultList containing GraphMatch objects, each of which contains a set of URIs of the matching graph elements.
For the above example, each result includes:
-
URI of an email message
-
URI of the edge connecting the email to a sender
-
URI of the sender, which would the the URI of the Person with email addresss “john@example.org“
-
URI of the edge connecting the email to a recipient
-
URI of the recipient Person, which is enforced to be not the same as the sender
4.Path Queries
5.Aggregation Queries
DISTINCT, COUNT, SUM, AVERAGE, FIRST, LAST, COUNT+DISTINCT, FIRST+DISTINCT, LAST+DISTINCT