Script loading and caching in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of script loading in Redis?

Script loading in Redis allows you to load Lua scripts into the server so they can be executed efficiently multiple times without sending the full script each time.

beginner

How does Redis cache scripts after loading them?

Redis caches scripts by storing their SHA1 hash. When you run a script, you can call it by its SHA1 hash instead of sending the full script again, saving bandwidth and improving speed.

beginner

What command is used to load a Lua script into Redis without running it?

The command is SCRIPT LOAD <script>. It loads the script and returns its SHA1 hash without executing it.

intermediate

What happens if you try to run a cached script by SHA1 hash but the script is not found in Redis?

Redis returns a NOSCRIPT error. You then need to send the full script again or reload it with SCRIPT LOAD.

beginner

Why is script caching useful in Redis?

Script caching reduces network traffic and speeds up execution by avoiding sending the full Lua script every time. It also ensures scripts run atomically on the server.

Which Redis command loads a Lua script and returns its SHA1 hash without executing it?

A SCRIPT RUN

B EVAL

C SCRIPT LOAD

D EVALSHA

SCRIPT LOAD loads the script and returns its SHA1 hash without running it.

What does Redis return if you try to run a script by SHA1 hash but the script is not cached?

A NOSCRIPT error

B SCRIPT NOT FOUND

C NULL

D OK

Redis returns a NOSCRIPT error if the script is not found in the cache.

Which command runs a cached Lua script by its SHA1 hash?

A EVALSHA

B SCRIPT LOAD

C EVAL

D SCRIPT EXEC

EVALSHA runs a cached script by its SHA1 hash.

Why is using script caching in Redis beneficial?

A It disables atomic execution

B It slows down script execution

C It increases network traffic

D It reduces bandwidth and speeds up execution

Caching reduces bandwidth and speeds up execution by avoiding sending full scripts repeatedly.

What is the SHA1 hash used for in Redis script caching?

A To encrypt the script

B To identify and run cached scripts

C To delete scripts

D To compile scripts

The SHA1 hash uniquely identifies cached scripts for running them efficiently.

Explain how Redis script loading and caching works and why it is useful.

Think about how sending scripts repeatedly can be slow and how caching helps.

Describe the steps to run a Lua script in Redis using script caching.

Focus on loading, running by hash, and error handling.