GET

The GET command in DiceDB is used to retrieve the value of a specified key. If the key exists, the value is written and if it does not then the command returns nil and an error is returned if the value stored at key is not a string. This is one of the most fundamental operations in DiceDB.

Syntax

GET key

Parameters

Parameter	Description	Type	Required
key	The name of the key whose value you want to retrieve. The key is a string.	string	Yes

Return Values

Condition	Return Value
The specified key exists and holds a string value	The string value stored at the key.
The specified key does not exist	nil
The specified key exists but is not a string, or multiple keys are passed	error

Behaviour

When the GET command is issued, DiceDB checks the existence of the specified key:

1. Key Exists and Holds a String: The value associated with the key is retrieved and returned.
2. Key Does Not Exist: The command returns nil
3. Key Exists but Holds a Non-string Value: An error is raised indicating that the operation against that key is not permitted.
4. Multiple Keys Passed: If multiple keys are passed to the GET command, an error is raised, as the command only accepts a single key at a time.

The GET command is a read-only operation and does not modify the state of the DiceDB database.

Errors

1. Expected string but got another type:

   • Error Message: (error) ERR expected string but got another type
   • Occurs when the specified key holds a value that is not a string (e.g., a list, set, hash, or zset). DiceDB uses strict type checking to ensure that the correct type of operation is performed on the appropriate data type.

2. Wrong number of arguments for ‘GET’ command:

   • Error Message: (error) ERR wrong number of arguments for ‘get’ command
   • Occurs when multiple keys are passed as parameters.

Example Usage

Here are a few examples demonstrating the usage of the GET command:

Key Exists and Holds a String Value

127.0.0.1:7379> SET mykey "Hello, DiceDB!"
127.0.0.1:7379> GET mykey
"Hello, DiceDB!"

Key Does Not Exist

127.0.0.1:7379> GET nonexistingkey
(nil)

Additional Notes

• Memory Usage: The value returned by the GET command occupies memory only during the command execution and is handed back to the client.
• Performance: The GET command is an O(1) operation, which means it has a constant time complexity regardless of the size of the value associated with the key.
• Atomicity: Like other individual DiceDB commands, GET is executed atomically. No other command can alter the key’s state during the execution of GET.