GETRANGE and SETRANGE in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis command GETRANGE do?

GETRANGE returns a substring of the string stored at a given key. You specify the start and end positions, and it returns the part of the string between them.

beginner

How does SETRANGE modify a string in Redis?

SETRANGE changes part of the string stored at a key, starting at a specified offset, by overwriting it with a new substring. If the string is shorter, it is extended with zero bytes.

intermediate

What happens if the end index in GETRANGE is beyond the string length?

GETRANGE returns the substring from the start index to the end of the string without error, even if the end index is beyond the string length.

intermediate

If you use SETRANGE with an offset larger than the current string length, what does Redis do?

Redis pads the string with zero bytes up to the offset, then writes the new substring starting at that offset.

intermediate

Can GETRANGE and SETRANGE be used on keys that do not exist?

GETRANGE on a non-existing key returns an empty string. SETRANGE on a non-existing key creates a new string padded with zero bytes as needed.

What does GETRANGE key 0 4 return if the string stored is 'hello world'?

A "hell"

B "hello"

C "hello "

D "ello"

GETRANGE uses 0-based inclusive indexes. For 'hello world', positions 0-4 are 'h','e','l','l','o' resulting in "hello".

If you run SETRANGE key 6 "Redis" on the string 'hello world', what is the new string?

A "hello Redisld"

B "hello Redisd"

C "hello Redis"

D "sideR olleh"

The string 'hello world' has length 11. Offset 6, 'Redis' length 5, overwrites positions 6-10 ('world') with 'Redis', resulting in 'hello Redis'.

What does GETRANGE return if the key does not exist?

A Empty string

B Error

C Null

D Zero bytes

GETRANGE on a non-existing key returns an empty string, not an error or null.

What happens if SETRANGE is used with an offset larger than the string length?

A Error is returned

B String is truncated

C Nothing happens

D String is padded with zero bytes up to offset

Redis pads the string with zero bytes up to the offset before writing the new substring.

Which command would you use to get a part of a string stored in Redis?

A GETRANGE

B SET

C GET

D SETRANGE

GETRANGE extracts a substring from a string stored at a key.

Explain how GETRANGE works in Redis and what happens if the requested range exceeds the string length.

Think about how you would cut a piece of a rope from start to end positions.

Describe how SETRANGE modifies a string in Redis and what happens if the offset is beyond the current string length.

Imagine painting over a wall starting at a certain point, and filling empty space if needed.