MGET

Atomically returns the string values of one or more keys.

Browse all commands · Upstream source documentation

Reference field	Value
Canonical name	MGET
Catalog group	String commands
Upstream since	1.0.0 — upstream Redis/module version, not an ffkv release
Pinned catalog	Redis 8.10.0

Syntax

MGET key [key ...]

ffkv behavior and limits

Keys and values are binary-safe bytes. Conditional SET and DELEX comparisons use the stored bytes; DIGEST uses XXH3, not a cryptographic digest.

Source: README.md:571–585; src/engine/strings.rs; tests/bdd/features/strings.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) where N is the number of keys to retrieve.

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

Command flags: READONLY, FAST.

ACL categories: STRING.

Command tips: REQUEST_POLICY:MULTI_SHARD.

Argument structure

Argument	Type	Constraints / metadata
key	key	multiple; key_spec_index: 0

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": -1,
        "step": 1,
        "limit": 0
      }
    }
  }
]

Additional pinned upstream metadata

{
  "group": "string",
  "since": "1.0.0"
}

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

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.

• A mixed-present multi-key migration request returns TRYAGAIN without mutation — tests/bdd/features/cluster.feature:460; invocation observed.
• Conditional rename retains both keys on collision and moves only to an absent destination — tests/bdd/features/generic.feature:1103; invocation observed.
• Rewritten journal preserves live values and deletes after restart — tests/bdd/features/server.feature:142; invocation observed.
• Sealed backup restores the seal boundary including incremental writes — tests/bdd/features/server.feature:164; invocation observed.
• Multi key strings overwrite other types and MGET returns null for nonstrings — tests/bdd/features/strings.feature:625; command tag and invocation observed.
• Counted multi set evaluates NX atomically and shares one expiration — tests/bdd/features/strings.feature:665; invocation observed.
• Multi set NX checks original existence and last duplicate wins — tests/bdd/features/strings.feature:761; invocation observed.
• Resolved multi string writes survive crash recovery with their expiration — tests/bdd/features/strings.feature:1043; invocation observed.
• Counted setters handle aliases before mutation and past absolute deadlines — tests/bdd/features/strings.feature:1178; invocation observed.
• A competing write aborts WATCH without applying queued changes — tests/bdd/features/transactions.feature:61; invocation observed.
• Invalid counted script keys fail during EXEC without discarding adjacent writes (Scenario Outline) — tests/bdd/features/transactions.feature:289; 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.

Multi set NX checks original existence and last duplicate wins — tests/bdd/features/strings.feature:771 (I execute:)

[
  "MGET",
  "a",
  "b"
]

Next source assertion: the reply equals:

["last","two"]

Counted setters handle aliases before mutation and past absolute deadlines — tests/bdd/features/strings.feature:1217 (I execute:)

[
  "MGET",
  "alias",
  "other"
]

Next source assertion: the reply equals:

["final",null]

Counted multi set evaluates NX atomically and shares one expiration — tests/bdd/features/strings.feature:679 (I execute:)

[
  "MGET",
  "existing",
  "new"
]

Next source assertion: the reply equals:

["original",null]