Lua script syntax in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a key "name" with value "Alice" in Redis using Lua.

Redis

redis.call('[1]', 'name', 'Alice')

Drag options to blanks, or click blank then click option'

Aget

Bset

Cdel

Dexists

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' instead of 'set' will try to retrieve a value, not store it.

Using 'del' deletes keys, which is not what we want here.

The set command stores a value for a key in Redis. Here, it sets key "name" to "Alice".

2fill in blank

medium

Complete the code to increment the integer value stored at key "counter" by 1.

Redis

redis.call('[1]', 'counter')

Drag options to blanks, or click blank then click option'

Aincr

Bdecr

Cappend

Dset

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'decr' will decrease the value instead of increasing it.

Using 'append' is for strings, not numbers.

The incr command increases the integer value of a key by 1.

3fill in blank

hard

Fix the error in the code to get the value of key "user".

Redis

local val = redis.call('[1]', 'user')

Drag options to blanks, or click blank then click option'

Adel

Bset

Cget

Dexists

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'set' tries to assign a value, not get it.

Using 'del' deletes the key, which is not intended.

The get command retrieves the value of a key in Redis.

4fill in blank

hard

Fill both blanks to check if key "session" exists and delete it if it does.

Redis

if redis.call('[1]', 'session') == 1 then
  redis.call('[2]', 'session')
end

Drag options to blanks, or click blank then click option'

Aexists

Bdel

Cget

Dset

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' to check existence returns the value, not a boolean.

Using 'set' instead of 'del' will overwrite the key.

exists checks if the key is present (returns 1 if yes). del deletes the key.

5fill in blank

hard

Fill both blanks to set key "count" to 10 only if it does not exist, then get its value.

Redis

redis.call('[1]', 'count', 10)
local val = redis.call('[2]', 'count')
return val

Drag options to blanks, or click blank then click option'

Asetnx

Bget

Cset

Ddel

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'set' instead of 'setnx' overwrites the key unconditionally.

Using 'del' deletes the key, which is not intended.

setnx sets the key only if it does not exist. get retrieves the value. set is not used here but included as a distractor.