Clarify exists() function: property existence only, not graph patterns

[Copilot]

exists(pattern) docs implied arbitrary graph patterns are supported. In practice, only property existence checks work — e.g. exists(n.prop). Passing relationship patterns like exists((n)-[]-()) errors out.

• Changed signature from exists(_pattern_) to exists(_entity.property_) to reflect actual behavior
• Updated description to "Returns true when the specified property exists on a given node or relationship"
• Added note that graph patterns are unsupported, linking to FalkorDB#1315 and pointing users to pattern predicates in WHERE as the alternative

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Clarify exists(pattern) function limitations</issue_title>
<issue_description>## Context

Migrated from FalkorDB/FalkorDB#1315.

Issue

The functions documentation describes the exists() predicate function as:

exists(pattern) — Returns true when at least one match for pattern exists

This implies that any graph pattern is supported. However, in practice, attempting to use exists() with a relationship pattern returns an error:

GRAPH.QUERY g "MATCH (n) WHERE exists((n)-[]-()) RETURN *"
(error) Unable to resolve filtered alias '(n)-[]-()'

Verified on FalkorDB v4.16.7 — the error still occurs.

Suggested Fix

Either:

1. Update the docs to clarify what pattern types exists() actually supports (e.g., only property existence checks like exists(n.prop), or only specific pattern forms), or
2. Note this as a known limitation and link to the related bug in the FalkorDB repo.

The WHERE clause docs show that pattern predicates work in WHERE directly (e.g., WHERE (p)-[:WON]->(s)), so users may be confused about why the same pattern doesn't work inside exists().</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Clarify exists(pattern) function limitations #395

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[Copilot]

Pull request overview

Updates the Cypher functions reference to accurately document FalkorDB’s exists() predicate as a property-existence check (not an arbitrary graph pattern existence predicate), and guides users to the correct alternative for graph-pattern filtering.

Changes:

• Adjusted the documented signature from exists(_pattern_) to exists(_entity.property_).
• Updated the description to clarify it checks for property existence on nodes/relationships.
• Added a note that graph patterns are unsupported in exists(), linking to FalkorDB#1315 and pointing to WHERE pattern predicates.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.