KEYS command in redis

KEYS pattern

Returns all the keys matching the glob-style pattern as space-separated strings.

For example, if you have in the database the keys "foo" and "foobar" the command "KEYS foo*" will return "foo foobar".

TIME COMPLEXITY: O(n) (with n being the number of keys in the DB, and assuming keys and pattern of limited length).

Note: Use \ to escape special chars if you want to match them verbatim.

RETURN VALUE: Bulk reply, specifically a string in the form of a space-separated list of keys. 

Syntax:

KEYS PATTERN

Example 1: When the keys with patterns are present

redis:6379> SET hello 178
"OK"
redis:6379> SET heeello 190
"OK"
redis:6379> SET hillo 109
"OK"
redis:6379> KEYS h*llo
1) "hello"
2) "heeello"
3) "hillo"

Output

1) "hello"

2) "heeello"

3) "hillo"

Example 2: When the keys with the pattern are not present

redis:6379> KEYS h*llo
(empty array)

Output

empty array