Lua vs transactions comparison in Redis

Introduction

We use Lua scripts and transactions in Redis to make sure multiple commands run together safely without interference.

When you want to run several Redis commands as one group without other commands interrupting.

When you need to do complex logic that Redis commands alone can't handle easily.

When you want to make sure data changes happen all at once or not at all.

When you want to improve performance by sending many commands in one step.

When you want to avoid race conditions in your Redis data.

Syntax

Redis

Transactions:
MULTI
command1
command2
...
EXEC

Lua script:
EVAL script numkeys key [key ...] arg [arg ...]

Transactions group commands between MULTI and EXEC to run atomically.

Lua scripts run custom code inside Redis, also atomically, and can do complex logic.

Examples

This transaction increments two counters together safely.

Redis

MULTI
INCR counter
INCR another_counter
EXEC

This Lua script increments the 'counter' key by 1 atomically.

Redis

EVAL "return redis.call('INCR', KEYS[1])" 1 counter

Sample Program

This transaction increments the 'visits' key twice safely in one atomic operation.

Redis

MULTI
INCR visits
INCR visits
EXEC

Important Notes

Transactions queue commands and run them all at once with EXEC.

Lua scripts run all commands inside one script, so you can use logic like loops and conditions.

Lua scripts can be faster because they reduce network round trips.

Summary

Both Lua scripts and transactions make Redis commands run atomically.

Transactions are simple command groups; Lua scripts allow complex logic.

Use Lua scripts for advanced operations and transactions for simple grouped commands.