Unsupported Redis commands

Common Redis commands fastcached does not implement, with a hint where one exists. Anything not listed here and not on the supported list returns -ERR unknown command.

The supported list is the authoritative one: it is derived from CommandTable and checked against it by ctest -R resp-command-docs. This page is prose, so read it as a hint about a family rather than as a per-verb ruling.

Data-structure commands

Lists (LPUSH, RPUSH, LPOP, RPOP, LRANGE, LLEN, …), hashes (HSET, HGET, HGETALL, …), sorted sets (ZADD, ZRANGE, ZRANGEBYSCORE, …) and bitfields are not supported.

Sets and streams are, in part — see the supported list. Sets carry SADD, SREM, SCARD, SISMEMBER, SMISMEMBER, SMEMBERS and SPOP; the set-algebra verbs are the ones still absent:

SINTER, SINTERSTORE, SUNION, SUNIONSTORE, SDIFF, SDIFFSTORE, SRANDMEMBER, SMOVE, SSCAN.

Streams are complete enough for consumer groups (15 verbs, XADD through XAUTOCLAIM).

If a key-value workflow currently uses a list or hash as a serialized blob, store it via SET and unpack on the client.

Key enumeration

KEYS, SCAN, RANDOMKEY, DBSIZE and TYPE are not implemented, and neither is memcached's stats cachedump. There is no way to enumerate the keyspace from a client on any protocol fastcached speaks.

Pub / sub

Implemented: SUBSCRIBE, UNSUBSCRIBE, PSUBSCRIBE, PUNSUBSCRIBE and PUBLISH, with keyspace notifications for the Redis write verbs. PUBSUB CHANNELS / NUMSUB / NUMPAT and SPUBLISH / SSUBSCRIBE (sharded pub/sub) are not.

Scripting

EVAL, EVALSHA, SCRIPT * are not implemented.

Transactions

Implemented: MULTI, EXEC, DISCARD, WATCH, UNWATCH. A WATCH is dirtied by a write on any protocol, so a memcached set aborts a Redis transaction watching that key.

For a single conditional write with no transaction, memcached's cas or meta ms C(token) is cheaper.

Cluster / replication

Cluster commands (CLUSTER *), replication commands (REPLICAOF, SLAVEOF, SYNC, PSYNC), and persistence commands (BGSAVE, BGREWRITEAOF) are not implemented. fastcached is a single-node cache with its own persistence story (see the persistent-storage docs in the project source).

Multiple databases

SELECT is accepted as a no-op for any index (it always replies +OK) so client connection setup succeeds, but fastcached has a single flat keyspace and the index is ignored. See SELECT.

Server commands

MONITOR, LASTSAVE, OBJECT *, MEMORY *, LATENCY *, SLOWLOG * are not implemented. Use fastcached's stats (memcached text protocol), the /metrics endpoint, or fastcache-cli stats for similar information.

DEBUG is implemented, for one sub-command: DEBUG PROTOCOL <type> emits one reply of each RESP type so a conformance client can validate the codec. LOLWUT answers with a version banner.

CLIENT and CONFIG are accepted as compatibility stubs rather than fully implemented — they answer the handshake probes Redis client libraries send on connect (CLIENT SETNAME / SETINFO / ID / GETNAME, CONFIG GET) without holding any real state. See CLIENT and CONFIG.