ZCARD

Returns the number of members in a sorted set.

Browse all commands · Upstream source documentation

Reference field	Value
Canonical name	ZCARD
Catalog group	Sorted set commands
Upstream since	1.2.0 — upstream Redis/module version, not an ffkv release
Pinned catalog	Redis 8.10.0

Syntax

ZCARD key

ffkv behavior and limits

Scores and lexicographic ranges are separate query modes. Do not rely on random-pop order; sorted-set storage remains RAM-resident in hybrid mode.

Source: README.md:275–295, 810–825; tests/bdd/features/sorted_sets.feature.

All requests share the 8 MiB framing/1,024-argument ingress limit; normal RESP replies have 64 MiB wire/logical budgets with bounded nesting/value counts. Management and Lua origins impose smaller budgets. These are not a process RSS cap. Catalog inclusion is not exhaustive option or wire-format parity. See limits and compatibility.

Upstream metadata

The following fields come from the pinned Redis metadata, not measured ffkv performance or an assertion that ffkv enforces every upstream flag. Running COMMAND INFO/COMMAND DOCS describe the current engine.

Upstream Redis complexity: O(1)

Upstream arity: 2 (includes the command name; a negative number is a minimum).

Command flags: READONLY, FAST.

ACL categories: SORTEDSET.

Argument structure

Argument	Type	Constraints / metadata
key	key	key_spec_index: 0

Key specifications

Upstream key discovery descriptors (indexes are relative to the full command vector):

[
  {
    "flags": [
      "RO"
    ],
    "begin_search": {
      "index": {
        "pos": 1
      }
    },
    "find_keys": {
      "range": {
        "lastkey": 0,
        "step": 1,
        "limit": 0
      }
    }
  }
]

Additional pinned upstream metadata

{
  "group": "sorted_set",
  "since": "1.2.0"
}

Metadata source · Local snapshot: src/command_metadata.json, key zcard.

BDD coverage and source examples

These are source observations, not a test run performed by this documentation build. A tag identifies scenario intent; an extracted vector identifies a command invocation, which may intentionally produce an error. Scenarios may require setup, multiple connections, persistence, cluster nodes or native-module fixtures.

• Underflowing geo arguments cannot delete an aliased source destination (Scenario Outline) — tests/bdd/features/geo.feature:165; invocation observed.
• Explicit zero and representable subnormal geo numbers are valid (Scenario Outline) — tests/bdd/features/geo.feature:200; invocation observed.
• Cardinality counts distinct members rather than score pairs — tests/bdd/features/sorted_sets.feature:44; command tag and invocation observed.
• Minimum pop orders ties and accepts zero without consuming data — tests/bdd/features/sorted_sets.feature:473; invocation observed.
• Random members distinguish scalar and repeated scored arrays — tests/bdd/features/sorted_sets.feature:529; invocation observed.
• Malformed range bounds and limits leave data unchanged — tests/bdd/features/sorted_sets.feature:1035; invocation observed.
• Multi pop validates count and timeout before taking a member — tests/bdd/features/sorted_sets.feature:1066; invocation observed.

Extracted command vectors

The following JSON arrays are the test harness’s argument vectors, not shell commands. Numeric arguments are converted by the harness; objects of the form {"base64":"…"} represent decoded binary bytes, not a literal JSON command argument. Preserve scenario setup and connection ordering. See the CLI guide for shell quoting and binary stdin. No reply is invented or inferred.

Underflowing geo arguments cannot delete an aliased source destination — tests/bdd/features/geo.feature:184 (I execute:)

Expanded from an actual Examples row: longitude=0, latitude=0, radius=1e-9999.

[
  "ZCARD",
  "geo"
]

Next source assertion: the reply equals:

1

Cardinality counts distinct members rather than score pairs — tests/bdd/features/sorted_sets.feature:50 (I execute:)

[
  "ZCARD",
  "ranked"
]

Next source assertion: the reply equals:

4

Random members distinguish scalar and repeated scored arrays — tests/bdd/features/sorted_sets.feature:559 (I execute:)

[
  "ZCARD",
  "single"
]

Next source assertion: the reply equals:

1