BITPOS

Finds the first set (1) or clear (0) bit in a string.

Browse all commands · Upstream source documentation

Reference field	Value
Canonical name	BITPOS
Catalog group	Bitmap commands
Upstream since	2.8.7 — upstream Redis/module version, not an ffkv release
Pinned catalog	Redis 8.10.0

Syntax

BITPOS key bit [start [end [BYTE | BIT]]]

ffkv behavior and limits

Bitmap/bitfield values share string key storage. Bitfield overflow policy and signedness affect arithmetic; request and reply budgets still apply.

Source: README.md:275–280, 784–797; tests/bdd/features/bitmaps.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(N)

Upstream arity: -3 (includes the command name; a negative number is a minimum).

Command flags: READONLY.

ACL categories: BITMAP.

Argument structure

Argument	Type	Constraints / metadata
key	key	key_spec_index: 0
bit	integer	Required
range	block	optional
↳ start	integer	Required
↳ end-unit-block	block	optional
↳ ↳ end	integer	Required
↳ ↳ unit	oneof	optional; since: 7.0.0
↳ ↳ ↳ byte	pure-token	token: BYTE
↳ ↳ ↳ bit	pure-token	token: BIT

Key specifications

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

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

Additional pinned upstream metadata

{
  "group": "bitmap",
  "since": "2.8.7",
  "history": [
    [
      "7.0.0",
      "Added the `BYTE|BIT` option."
    ]
  ]
}

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

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.

• Bit offsets cross byte boundaries and range units are inclusive — tests/bdd/features/bitmaps.feature:5; command tag and invocation observed.
• Missing bitmaps read as zero without creating a key — tests/bdd/features/bitmaps.feature:123; command tag and invocation observed.
• BITPOS rejects non-string inputs without mutation — tests/bdd/features/bitmaps.feature:553; command tag and 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.

Bit offsets cross byte boundaries and range units are inclusive — tests/bdd/features/bitmaps.feature:79 (I execute:)

[
  "BITPOS",
  "bits",
  "1"
]

Next source assertion: the reply equals:

7

Missing bitmaps read as zero without creating a key — tests/bdd/features/bitmaps.feature:141 (I execute:)

[
  "BITPOS",
  "missing",
  "0"
]

Next source assertion: the reply equals:

0

BITPOS rejects non-string inputs without mutation — tests/bdd/features/bitmaps.feature:559 (I execute:)

[
  "BITPOS",
  "bad",
  "1"
]

Next source assertion: the reply is an error with code “WRONGTYPE”