EVAL command for Lua execution in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to run a Lua script that returns the value of key 'mykey'.

Redis

EVAL "return redis.call('GET', [1])" 1 mykey

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

Amykey"

Bmykey

C"mykey"

D'mykey'

Attempts:

3 left

💡 Hint

Common Mistakes

Using the key name without quotes causes a syntax error.

Using mismatched quotes breaks the script.

The Lua script needs the key name as a string, so it must be enclosed in single quotes inside the double-quoted script.

2fill in blank

medium

Complete the code to run a Lua script that increments the value of key 'counter' by 1.

Redis

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

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

Acounter'

Bcounter

C'counter'

D"counter"

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting quotes around the key name.

Using mismatched or incorrect quotes.

The key name must be a string inside the Lua script, so it needs single quotes.

3fill in blank

hard

Fix the error in the Lua script that returns the length of the value stored at key 'data'.

Redis

EVAL "return string.len(redis.call('GET', [1]))" 1 data

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

A'data'

Bdata

C"data"

Ddata"

Attempts:

3 left

💡 Hint

Common Mistakes

Using unquoted key names causing syntax errors.

Mismatched quotes inside the script.

The key name must be a string literal inside the Lua script, so it needs single quotes.

4fill in blank

hard

Fill all three blanks to run a Lua script that sets key 'name' to 'Alice' and returns the new value.

Redis

EVAL "redis.call([1], [2], [3]); return redis.call('GET', 'name')" 1 name

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

A'SET'

B'name'

C'Alice'

D'GET'

Attempts:

3 left

💡 Hint

Common Mistakes

Using unquoted command or key names.

Swapping the order of command and key.

The first argument to redis.call is the command 'SET' as a string, the second is the key name 'name' as a string, the third is the value 'Alice' as a string.

5fill in blank

hard

Fill all three blanks to run a Lua script that sets key 'age' to 30 and returns the value as a number.

Redis

EVAL "redis.call([1], [2], [3]); return tonumber(redis.call('GET', 'age'))" 1 age

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

A'SET'

B'age'

C'30'

D'GET'

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting the value '30'.

Using wrong order of arguments.

Forgetting to convert the returned value to number.

The command is 'SET', the key is 'age', and the value is '30' as a string. Then the script returns the numeric value.