This document is based on the Cypher Query Language Reference (version 9), available at OpenCypher Resources.

Patterns

Patterns are fully supported.

Types

Structural types

• Nodes
• Relationships
• Path variables (alternating sequence of nodes and relationships).

Composite types

• Lists

• Maps

  Unsupported:

• Temporal types (Date, DateTime, LocalDateTime, Time, LocalTime, Duration)

Literal types

• Numeric types (64-bit doubles and 64-bit signed integer representations)
• String literals

• Booleans

  Unsupported:

• Hexadecimal and octal numerics

Other

NULL is supported as a representation of a missing or undefined value.

Comparability, equality, orderability, and equivalence

This is a somewhat nebulous area in Cypher itself, with a lot of edge cases. Broadly speaking, FalkorDB behaves as expected with string and numeric values. There are likely some behaviors involving the numerics NaN, -inf, inf, and possibly -0.0 that deviate from the Cypher standard. We do not support any of these properties at the type level, meaning nodes and relationships are not internally comparable.

Clauses

Reading Clauses

• MATCH

• OPTIONAL MATCH

  Unsupported:

• Label expressions

Projecting Clauses

• RETURN
• AS
• WITH
• UNWIND

Reading sub-clauses

• WHERE
• ORDER BY
• SKIP
• LIMIT

Writing Clauses

• CREATE
• DELETE
  • We actually implement DETACH DELETE, the distinction being that relationships invalidated by node deletions are automatically deleted.

• SET

  Unsupported:

• REMOVE (to modify properties)
  • Properties can be deleted with SET [prop] = NULL.

Reading/Writing Clauses

• MERGE
• CALL (procedures)
  • The currently-supported procedures are listed in the Procedures documentation.

Set Operations

• UNION
• UNION ALL

Functions

The currently-supported functions are listed in the Functions documentation.

Unsupported:

• Temporal arithmetic functions
• User-defined functions

Operators

Mathematical operators

The currently-supported functions are listed in the mathematical operators documentation.

String operators

• String operators (STARTS WITH, ENDS WITH, CONTAINS) are supported.

  Unsupported:

• Regex operator

Boolean operators

• AND
• OR
• NOT
• XOR

Parameters

Parameters may be specified to allow for more flexible query construction:

CYPHER name_param = "Niccolò Machiavelli" birth_year_param = 1469 MATCH (p:Person {name: $name_param, birth_year: $birth_year_param}) RETURN p

The example above shows the syntax used by redis-cli to set parameters, but each FalkorDB client introduces a language-appropriate method for setting parameters, and is described in their documentation.

Non-Cypher queries

• FalkorDB provides the GRAPH.EXPLAIN command to print the execution plan of a provided query.
• GRAPH.DELETE will remove a graph and all Redis keys associated with it.
• We do not currently provide support for queries that retrieve schemas, though the LABELS and TYPE scalar functions may be used to get a graph overview.