XCFGSET

Sets the IDMP configuration parameters for a stream.

Browse all commands · Upstream source documentation

Reference field	Value
Canonical name	XCFGSET
Catalog group	Stream commands
Upstream since	8.6.0 — upstream Redis/module version, not an ffkv release
Pinned catalog	Redis 8.10.0

Syntax

XCFGSET key [IDMP-DURATION idmp-duration]
  [IDMP-MAXSIZE idmp-maxsize]

ffkv behavior and limits

Stream waits are bounded to 65,536 clients and 64 MiB of retained logical requests (also limited by the connection cap). Approximate MAXLEN trimming uses 100-entry granularity. EXEC/Lua reads never block. Physical index statistics describe ffkv, not Redis allocator internals.

Source: README.md:351–374; tests/bdd/features/streams.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: WRITE, FAST.

ACL categories: STREAM.

Argument structure

Argument	Type	Constraints / metadata
key	key	key_spec_index: 0
idmp-duration	integer	optional; token: IDMP-DURATION
idmp-maxsize	integer	optional; token: IDMP-MAXSIZE

Key specifications

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

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

Additional pinned upstream metadata

{
  "group": "stream",
  "since": "8.6.0"
}

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

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.

• Idempotency replay retains original payload and configuration reset permits a fresh append — tests/bdd/features/streams.feature:497; 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.

Idempotency replay retains original payload and configuration reset permits a fresh append — tests/bdd/features/streams.feature:573 (I execute:)

[
  "XCFGSET",
  "events",
  "IDMP-MAXSIZE",
  3
]

Next source assertion: the reply equals:

"OK"

Idempotency replay retains original payload and configuration reset permits a fresh append — tests/bdd/features/streams.feature:503 (I execute:)

[
  "XCFGSET",
  "events",
  "IDMP-DURATION",
  300,
  "IDMP-MAXSIZE",
  2
]

Next source assertion: the reply equals:

"OK"