HIMPORT PREPARE

Defines a session-local fieldset that maps a name to a sorted set of field names.

Browse all commands · Upstream source documentation

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

Syntax

HIMPORT PREPARE fieldset-name field [field ...]

ffkv behavior and limits

Hash fields have independent expiration. Counted field forms use FIELDS n; HSETEX counts field/value pairs. Key TTL and field TTL are distinct.

Source: README.md:587–599; tests/bdd/features/hashes.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*log(N)) where N is the number of fields.

Upstream arity: -4 (includes the command name; a negative number is a minimum).

Command flags: DENYOOM.

ACL categories: HASH.

Command tips: REQUEST_POLICY:ALL_SHARDS.

Argument structure

Argument	Type	Constraints / metadata
fieldset-name	string	Required
field	string	multiple

Additional pinned upstream metadata

{
  "group": "hash",
  "since": "8.10.0"
}

Metadata source · Local snapshot: src/command_metadata.json, key himport|prepare.

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.

• Prepared layouts preserve declared field order and replace complete hashes — tests/bdd/features/hashes.feature:877; command tag and invocation observed.
• Duplicate layout preparation and mismatched imports preserve old state — tests/bdd/features/hashes.feature:934; command tag and invocation observed.
• Discarding session definitions never removes imported hashes — tests/bdd/features/hashes.feature:984; invocation observed.
• Replacing layout definitions affects only future imports — tests/bdd/features/hashes.feature:1076; command tag and invocation observed.
• Import layouts are isolated per connection — tests/bdd/features/hashes.feature:1117; command tag and invocation observed.
• Reset forgets definitions without changing imported hashes — tests/bdd/features/hashes.feature:1146; command tag and invocation observed.
• Imported values survive recovery without resurrecting session definitions — tests/bdd/features/hashes.feature:1175; invocation observed.
• Transactions apply session imports in execution order — tests/bdd/features/hashes.feature:1197; command tag and invocation observed.
• Discarded transactions never discard prepared definitions — tests/bdd/features/hashes.feature:1229; invocation observed.
• Scripts use invocation-local layouts rather than the network session — tests/bdd/features/hashes.feature:1253; command tag and invocation observed.
• Import names fields and values are binary safe — tests/bdd/features/hashes.feature:1287; command tag and invocation observed.
• Each outer Lua invocation owns a fresh import session rather than borrowing network layouts — tests/bdd/features/scripting.feature:623; 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.

Replacing layout definitions affects only future imports — tests/bdd/features/hashes.feature:1083 (I execute:)

[
  "HIMPORT",
  "PREPARE",
  "layout",
  "new"
]

Next source assertion: the reply equals:

"OK"

Import names fields and values are binary safe — tests/bdd/features/hashes.feature:1289 (I execute:)

Binary payload: decode the base64 object to bytes using a client API or binary stdin; do not send the base64 text as the value.

[
  "HIMPORT",
  "PREPARE",
  {
    "base64": "AP8="
  },
  {
    "base64": "/wA="
  },
  ""
]

Next source assertion: the reply equals:

"OK"

Discarding session definitions never removes imported hashes — tests/bdd/features/hashes.feature:986 (the following commands succeed:)

[
  "HIMPORT",
  "PREPARE",
  "one",
  "a"
]