Cypher coverage

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

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.