FT.ALTER

Adds a new field to the index

Browse all commands · Upstream source documentation

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

Syntax

FT.ALTER index [SKIPINITIALSCAN] SCHEMA ADD field options

ffkv behavior and limits

Search worker configuration controls a real Rayon pool; GC schedules generation-fenced Rust compaction, not a POSIX fork. Search indexes and documents are bounded and RAM-resident; upstream syntax is not a promise of every option combination or Redis module ABI parity.

Source: README.md:375–377, 636–642; src/engine/search/; tests/bdd/features/search.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.

Metadata availability

This command is in the canonical catalog but has no matching entry in the pinned src/command_metadata.json. Argument flags, complexity and key specifications are not invented. Use the syntax, upstream source documentation and actual scenario evidence below.

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.

• ALTER validates a full new schema before rescanning existing documents — tests/bdd/features/search.feature:255; command tag and invocation observed.
• Recovery retains intentionally unindexed initial data and metadata namespaces — tests/bdd/features/search.feature:944; command tag and invocation observed.
• Disposable Lua debugging sees staged search changes without publishing catalog changes — tests/bdd/features/search.feature:1316; 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.

Disposable Lua debugging sees staged search changes without publishing catalog changes — tests/bdd/features/search.feature:1371 (I execute:)

[
  "FT.ALTER",
  "idx",
  "SCHEMA",
  "ADD",
  "tag",
  "TAG"
]

Next source assertion: the reply equals:

"OK"

ALTER validates a full new schema before rescanning existing documents — tests/bdd/features/search.feature:257 (the following commands succeed:)

[
  "FT.ALTER",
  "idx",
  "SCHEMA",
  "ADD",
  "price",
  "NUMERIC",
  "SORTABLE"
]

Recovery retains intentionally unindexed initial data and metadata namespaces — tests/bdd/features/search.feature:946 (the following commands succeed:)

[
  "FT.ALTER",
  "idx",
  "SKIPINITIALSCAN",
  "SCHEMA",
  "ADD",
  "price",
  "NUMERIC"
]