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

> ## Agent Instructions
> FalkorDB is a graph database that speaks the Redis protocol. Queries are issued as OpenCypher through the GRAPH.QUERY and GRAPH.RO_QUERY commands, not over Bolt or a SQL connection.
> FalkorDB implements a subset of OpenCypher with proprietary extensions. Do not assume Neo4j-only syntax or procedures are available — check /cypher/cypher-support and /cypher/known-limitations before using a clause.
> FalkorDB is the successor to RedisGraph, but they are separate products. Do not present RedisGraph commands, versions, or limitations as current FalkorDB behavior.
> Use the official clients listed in /getting-started/clients rather than generic Redis or Neo4j drivers, and prefer the language the user is already working in.
> Configuration parameters are set with GRAPH.CONFIG SET or at startup; cite the exact parameter name from /getting-started/configuration rather than inventing one.
> This site covers four products: FalkorDB (core), FalkorDB Cloud, FalkorDB Enterprise, and the GraphRAG SDK. Name which one an answer applies to, since setup and operations differ.

# Collection Functions

> FLEX collection functions for set operations, frequency analysis, and list manipulation in Cypher queries.

FLEX collections utilities.

## Frequently Asked Questions

<AccordionGroup>
  <Accordion title="What are FLEX collection functions?">
    FLEX collection functions provide set operations and list transformations including union, intersection, shuffling, frequency counting, and zipping lists together.
  </Accordion>

  <Accordion title="How do I call a collection function?">
    Use the namespace `flex.coll.<function>()`. For example: `flex.coll.union([1,2,3], [3,4,5])` returns `[1,2,3,4,5]`.
  </Accordion>

  <Accordion title="Do collection functions modify the original list?">
    No. All FLEX collection functions return new lists and do not mutate the input values.
  </Accordion>
</AccordionGroup>