EVAL
Run a Lua script server-side; routed to KEYS[1]'s shard when numkeys >= 1.
EVAL script numkeys [key [key ...]] [arg [arg ...]]Complexity
O(compile + the script's own work). The whole script is one atomic unit on KEYS[1]'s shard and blocks that shard for its duration. The runaway guard is an INSTRUCTION budget (lua time_limit_ms x 40000 instructions), not a wall clock
Complexity and compatibility are read out of kevy's implementation, not copied from Redis's reference. Several genuinely differ.
Redis compatibility
Differs
there is no -BUSY state and no SCRIPT KILL — an over-budget script is aborted in place and answered with an ordinary error; nested EVAL is rejected, a redis.call touching another shard's key returns CROSSSLOT, and EVAL auto-caches its source by SHA1 so EVALSHA works without SCRIPT LOAD