EXISTS

Syntax

EXISTS key [key ...]

Description

The EXISTS command checks if the specified key(s) exist in Echo DB. It returns the number of keys that exist. Keys that have expired are considered non-existent.

Arguments

• key (required, one or more): The name(s) of the key(s) to check.

Return Value

Returns an Integer: The number of keys that exist (between 0 and the number of keys specified).

Examples

Checking a Single Key

SET mykey "value"
EXISTS mykey

Response:

OK
(integer) 1

Checking a Non-Existent Key

EXISTS nonexistent

Response:

(integer) 0

Checking Multiple Keys

SET key1 "value1"
SET key2 "value2"
EXISTS key1 key2 key3

Response:

OK
OK
(integer) 2

Checking Expired Keys

SET mykey "value"
EXPIRE mykey 1
# Wait 1 second
EXISTS mykey

Response:

OK
(integer) 1
(integer) 0

Notes

• Returns 1 if the key exists, 0 if it doesn't
• When checking multiple keys, returns the count of existing keys
• Expired keys are considered non-existent
• Works with both string and list keys

Use Cases

• Conditional Operations: Check if a key exists before performing operations
• Validation: Verify that required keys are present
• Monitoring: Count how many keys of a certain pattern exist
• Cache Checks: Verify if cached data exists before fetching

Related Commands

• GET - Get a key's value
• SET - Set a key's value
• DEL - Delete a key