5.1 About Graph Pattern

The GRAPH_TABLE operator in a SQL graph query contains a graph pattern.

A graph pattern is expressed between the input graph name and the COLUMNS clause inside the GRAPH_TABLE operator.

A graph pattern contains one or more comma-separated path patterns, which are composed of vertex and edge patterns. For example, the following path pattern has two vertex patterns and one edge pattern:

(v1) -[e]-> (v2)

A vertex pattern is enclosed in parentheses and specifies how to match a single vertex. An edge pattern is enclosed by a square bracket with delimiters on the left and right side of the edge pattern and specifies how to match a single edge.

Also, the available arrow tokens for edge patterns are summarized in the following table:

Table 5-1 Arrow Tokens for Edge Patterns

Directionality	Bracketed Syntax	Abbreviated SyntaxFoot 1
Directed to the right	-[ ]->	->
Directed to the left	<-[ ]-	->
Any directed edge (right or left)	<-[ ]-> or -[ ]-	-

^Footnote 1

• There are no brackets for the arrows in the “abbreviated syntax” column.
• All edge labels will be considered as no edge label is specified. Hence, filtering on a specific edge is not supported.

A graph element pattern (which can either be a vertex or an edge pattern) may in turn optionally include:

• An element variable.
• A label expression which is that part in an element pattern that starts with the keyword IS and is followed by a list of one or more label names. If there is more than one label name, then these are separated by vertical bars.
• An element pattern WHERE clause which expresses a search condition on the element variable declared by the element pattern.

See Also:

Graph Pattern in Oracle Database SQL Language Reference

The following sections explain the graph pattern concepts more in detail:

• Graph Element Variables
  Vertex and edge pattern variables ranges over vertices and edges respectively.
• Label Expressions
  A label expression in a vertex or an edge element pattern is introduced by the keyword IS.
• Accessing Label Properties
  You can access a property inside a graph element pattern, in the out-of-line WHERE clause or in the COLUMNS clause.