JSON

JSON keys contain parsed document trees rather than opaque JSON strings. Objects preserve ordering, and path operations address selected nodes. Use this family when applications need nested updates without a read/modify/rewrite round trip.

Store and select a document

target/release/ffkv-cli -p 6382 JSON.SET docs:json '$' '{"name":"Ada","items":[{"price":2},{"price":9}],"active":true}'
target/release/ffkv-cli -p 6382 JSON.GET docs:json '$'
target/release/ffkv-cli -p 6382 JSON.GET docs:json '$.items[?(@.price > 5)]'
target/release/ffkv-cli -p 6382 JSON.TYPE docs:json '$.items'
target/release/ffkv-cli -p 6382 JSON.NUMINCRBY docs:json '$.items[*].price' 1
target/release/ffkv-cli -p 6382 JSON.TOGGLE docs:json '$.active'

Quote paths and JSON to protect $, brackets, spaces, and quotes from the shell. JSONPath ($...) can select multiple nodes, so response shape can contain multiple matches even when the application expects one. Legacy paths have different selection/response conventions; do not silently switch path styles in a client.

Read selectors preserve occurrence order and duplicates: selecting $[1,0,1] from [10,20] returns [20,10,20], including through JSON.MGET. Mutation targets are distinct: the same selector increments or deletes each addressed node only once, rather than applying the update twice to index one.

JSON.SET NX/XX conditionally assigns according to path existence. New documents are created at the root; setting a nested path is not a general-purpose missing-parent constructor. JSON values must be valid JSON: a document string needs JSON quotes inside the shell argument.

Structured mutation

target/release/ffkv-cli -p 6382 JSON.ARRAPPEND docs:json '$.items' '{"price":12}'
target/release/ffkv-cli -p 6382 JSON.ARRLEN docs:json '$.items'
target/release/ffkv-cli -p 6382 JSON.OBJKEYS docs:json '$'
target/release/ffkv-cli -p 6382 JSON.GET docs:json '$.items[*].price'

ARRINSERT/ARRPOP/ARRTRIM work on arrays; STRAPPEND/STRLEN on strings; numeric and boolean commands on matching types. JSON.MERGE applies merge-patch semantics, while DEL/FORGET removes selected nodes and CLEAR resets eligible values; these are not synonyms. JSON.MSET coordinates multi-document writes atomically. A path matching nothing is different from an invalid expression or wrong node/key type.

Limits and durability

Compact documents cap at 4 MiB, 262,144 nodes, and depth 128. Paths cap at 16 KiB, matches at 65,536, and expression/projection work is bounded. Request/reply budgets may reject work earlier. These bounds are not a promise that every RedisJSON option or wire shape is identical.

Documents remain RAM-resident in hybrid mode. Key TTL, WATCH, ACL, WAL, checkpoints, and backups apply, but restart survival requires persistence. A lost mutation reply is ambiguous; prefer idempotent assignments over blind replay of numeric increments/appends.

Search indexes source JSON documents separately; index failure does not necessarily mean the source write failed. See JSON.SET, JSON.GET, hashes, and compatibility.