PUBLISH

Posts a message to a channel.

Browse all commands · Upstream source documentation

Reference field	Value
Canonical name	PUBLISH
Catalog group	Pub/Sub commands
Upstream since	2.0.0 — upstream Redis/module version, not an ffkv release
Pinned catalog	Redis 8.10.0

Syntax

PUBLISH channel message

ffkv behavior and limits

Pub/Sub is transient delivery, not durable leased jobs. Per client: 1,024 registrations, 8 MiB of names, 1,024-byte patterns, and 256 events/16 MiB of output. Overflow disconnects a slow subscriber; publications can fail the shared pattern-work budget.

Source: README.md:487–524; tests/bdd/features/pubsub.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+M) where N is the number of clients subscribed to the receiving channel and M is the total number of subscribed patterns (by any client).

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

Command flags: PUBSUB, LOADING, STALE, FAST, MAY_REPLICATE, SENTINEL.

Argument structure

Argument	Type	Constraints / metadata
channel	string	Required
message	string	Required

Additional pinned upstream metadata

{
  "group": "pubsub",
  "since": "2.0.0"
}

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

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.

• WRITE pauses hold may-replicate operations without holding reads (Scenario Outline) — tests/bdd/features/client_control_repair.feature:98; command tag and invocation observed.
• WRITE pause prevents delivery until the publisher is admitted (Scenario Outline) — tests/bdd/features/client_control_repair.feature:176; command tag and invocation observed.
• EXEC aggregates may-replicate pause classification from queued commands — tests/bdd/features/client_control_repair.feature:214; command tag and invocation observed.
• ACL LOG records only the rejected command, key or channel (Scenario Outline) — tests/bdd/features/client_control_repair.feature:344; invocation observed.
• RESET clears subscriptions, database, names, protocol and tracking without closing the connection — tests/bdd/features/connections.feature:686; invocation observed.
• A regular subscription delivers payloads and unsubscribe removes the recipient — tests/bdd/features/pubsub.feature:4; command tag and invocation observed.
• Patterns are unique in inspection but each matching registration receives its own message — tests/bdd/features/pubsub.feature:52; invocation observed.
• Shard channels are disjoint from regular channels even when their names match — tests/bdd/features/pubsub.feature:152; invocation observed.
• RESP3 subscription pushes do not prevent ordinary commands on the same connection — tests/bdd/features/pubsub.feature:230; command tag.
• Real cluster peer links forward shard publications to replicas and global publications across shards — tests/bdd/features/pubsub.feature:287; command tag and invocation observed.
• PubSub command grants cannot borrow channel grants from another selector — tests/bdd/features/server.feature:1221; 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.

EXEC aggregates may-replicate pause classification from queued commands — tests/bdd/features/client_control_repair.feature:220 (client “transaction” executes:)

[
  "PUBLISH",
  "news",
  "message"
]

Next source assertion: the reply equals:

"QUEUED"

Patterns are unique in inspection but each matching registration receives its own message — tests/bdd/features/pubsub.feature:78 (I execute:)

[
  "PUBLISH",
  "order:7",
  "paid"
]

Next source assertion: the reply equals:

2

A regular subscription delivers payloads and unsubscribe removes the recipient — tests/bdd/features/pubsub.feature:14 (I execute:)

[
  "PUBLISH",
  "orders",
  "created"
]

Next source assertion: the reply equals:

1