Redis SUNIONCARD returns set-union cardinality
Introduced 2026-07-29 · score 0.97
HOW TO USE IT
When you need the number of distinct members across multiple Redis sets, run `SUNIONCARD` with the number of keys followed by the set keys.
SUNIONCARD 2 <set-key-1> <set-key-2>WHY THIS HELPS
Get the cardinality of the union of multiple Redis sets.
REQUIREMENTS AND LIMITATIONS
- Version: 8.10.0
- numkeys (required): Number of set keys that follow.
- key [key ...] (required): One or more set keys to union; missing keys count as empty sets.
- APPROX: Return an approximate cardinality instead of an exact count.
- LIMIT limit: Stop counting at this cardinality; 0 (the default) means unlimited. Works in exact and approximate modes.
- Prerequisite: Available since Redis Open Source 8.10.0.
FIRST-PARTY EVIDENCE
Check the installed version and the source before using it. Entry JSON