> ## Documentation Index
> Fetch the complete documentation index at: https://new.docs.falkordb.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Cypher coverage

> FalkorDB implements a subset of the Cypher language, which is growing as development continues.

This document is based on the Cypher Query Language Reference (version 9), available at [OpenCypher Resources](https://www.opencypher.org/resources).

## Patterns

Patterns are fully supported.

## Types

### Structural types

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

### Composite types

* Lists
* Maps
* 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
* REMOVE (to modify properties and labels). See [REMOVE](/cypher/remove) for details.

### Reading/Writing Clauses

* MERGE
* CALL (procedures)
  * The currently-supported procedures are listed in [the Procedures documentation](/commands/graph.query#procedures).

### Set Operations

* UNION
* UNION ALL

## Functions

The currently-supported functions are listed in [the Functions documentation](/commands/graph.query#functions).

**Unsupported:**

* Temporal arithmetic functions
* User-defined functions

## Operators

### Mathematical operators

The currently-supported functions are listed in [the mathematical operators documentation](/commands/graph.query#mathematical-operators).

### 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:

```sh theme={null}
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.

## Frequently Asked Questions

<AccordionGroup>
  <Accordion title="What Cypher specification does FalkorDB follow?">
    FalkorDB is based on the **OpenCypher Query Language Reference version 9**, available at opencypher.org. It implements a growing subset of the specification with proprietary extensions.
  </Accordion>

  <Accordion title="Does FalkorDB support regular expressions?">
    No. The regex operator is not currently supported. Use the string operators `STARTS WITH`, `ENDS WITH`, and `CONTAINS` for pattern matching on strings.
  </Accordion>

  <Accordion title="Are user-defined functions supported?">
    Yes. FalkorDB supports user-defined functions through the **Flex UDF library**, which provides functions for text manipulation, collections, date/time, JSON, maps, bitwise operations, and similarity. See the [UDFs documentation](/udfs) for the full list of available functions.
  </Accordion>

  <Accordion title="How do I use query parameters?">
    Use the CYPHER prefix: `CYPHER name='Alice' MATCH (n {name: $name}) RETURN n`. Each FalkorDB client library also provides its own method for passing parameters.
  </Accordion>

  <Accordion title="What data types are supported?">
    FalkorDB supports 64-bit doubles, 64-bit signed integers, strings, booleans, NULL, lists, maps, and temporal types (Date, DateTime, LocalDateTime, Time, LocalTime, Duration). Hexadecimal and octal numerics are not supported.
  </Accordion>
</AccordionGroup>