TYPE command for key type check in Redis - Step-by-Step Execution

Concept Flow - TYPE command for key type check

Start

↓

Input key name

↓

Check if key exists

↓

Get key type

↓

Return type string

↓

End

The TYPE command checks if a key exists and returns its data type or 'none' if it does not exist.

Execution Sample

Redis

TYPE mykey
TYPE unknownkey

Check the data type of 'mykey' and 'unknownkey' keys in Redis.

Execution Table

Step	Command	Key	Key Exists?	Returned Type
1	TYPE mykey	mykey	Yes	string
2	TYPE unknownkey	unknownkey	No	none

💡 Execution stops after checking all requested keys.

Variable Tracker

Variable	Start	After Step 1	After Step 2
key	undefined	mykey	unknownkey
key_exists	undefined	true	false
type_result	undefined	string	none

Key Moments - 2 Insights

Why does TYPE return 'none' for some keys?

TYPE returns 'none' when the key does not exist in the database, as shown in step 2 of the execution_table.

Can TYPE return types other than 'string' or 'none'?

Yes, TYPE can return types like 'list', 'set', 'hash', or 'zset' depending on the stored data type, but in this example only 'string' and 'none' appear.

Visual Quiz - 3 Questions

Look at the execution_table, what is the returned type for 'mykey' at step 1?

A list

B none

C string

D hash

💡 Hint

Check the 'Returned Type' column in row 1 of the execution_table.

At which step does the TYPE command return 'none'?

A Step 1

B Step 2

C Both steps

D None

💡 Hint

Look at the 'Returned Type' column for each step in the execution_table.

If the key 'mykey' was deleted before step 1, what would TYPE return?

A none

B set

C string

D error

💡 Hint

Refer to the behavior shown in step 2 where the key does not exist.

Concept Snapshot

TYPE key
Returns the data type of the key.
If key exists, returns type like string, list, set, hash, zset.
If key does not exist, returns 'none'.
Useful to check key type before operations.

Full Transcript

The TYPE command in Redis checks the data type of a given key. First, it checks if the key exists. If it does, it returns the type as a string such as 'string', 'list', or 'hash'. If the key does not exist, it returns 'none'. For example, TYPE mykey returned 'string' because 'mykey' exists and holds a string. TYPE unknownkey returned 'none' because that key does not exist. This helps avoid errors by confirming the key type before performing operations.