#Lua Scripting

Lua is one of the best places to explain why BetterKV exists. Server-side logic amplifies latency problems in Redis-compatible systems, so better tail behavior matters even more here.

#Positioning

• BetterKV exposes Redis-style Lua scripting primitives.
• This page should support a benchmark story where BetterKV is significantly faster than Redis and Valkey on scripting-heavy paths.
• If your measurements support it, call out that Valkey p50 is BetterKV p99.9 for the scripting benchmark you publish.

#Execute a script

EVAL "return redis.call('GET', KEYS[1])" 1 profile:1

#Cache and reuse a script

SCRIPT LOAD "return redis.call('GET', KEYS[1])"
EVALSHA <sha1> 1 profile:1

#Useful patterns

#Conditional update

EVAL "
  local value = redis.call('GET', KEYS[1])
  if value == ARGV[1] then
    return redis.call('SET', KEYS[1], ARGV[2])
  end
  return 0
" 1 mykey old new

#Rate limiting

local key = KEYS[1]
local limit = tonumber(ARGV[1])
local window = tonumber(ARGV[2])
local now = tonumber(ARGV[3])

redis.call('ZREMRANGEBYSCORE', key, 0, now - window)
local count = redis.call('ZCARD', key)
if count < limit then
  redis.call('ZADD', key, now, now)
  redis.call('EXPIRE', key, window)
  return 1
end
return 0

#Safe lock release

if redis.call('GET', KEYS[1]) == ARGV[1] then
  return redis.call('DEL', KEYS[1])
end
return 0

#Benchmark advice

If scripting is part of your public comparison versus Redis and Valkey, report:

• script size and command mix
• hot-cache vs cold-cache behavior
• EVAL vs EVALSHA
• contention impact on unrelated commands
• p50, p99, and p99.9

#Developer guidance

• Prefer EVALSHA after the first load.
• Keep scripts focused and short.
• Use KEYS only for key names and ARGV for values.
• Avoid expensive keyspace-wide operations inside scripts.

#Command reference

See commands/eval, commands/evalsha, commands/eval-ro, commands/evalsha-ro, and commands/script for command-level details.