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Strings are Cache-Pot’s most fundamental data type. Every string value is a sequence of bytes — you can store plain text, serialized JSON, binary blobs, or numeric strings that you increment and decrement in place. All the commands on this page operate on keys whose type is string. Values are capped at 512 MB.
String values are limited to 512 MB. SETRANGE enforces this limit and returns an error if the resulting string would exceed it.

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GET

Returns the value stored at key. Returns nil (null bulk string) when the key does not exist. Syntax: GET key 
SET greeting "hello"
GET greeting
# "hello"

GET nonexistent
# (nil)
Returns: Bulk string, or nil if the key does not exist.

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SET

Sets key to value. Optionally sets a TTL or enforces a conditional write. Syntax: SET key value [EX seconds | PX milliseconds] [NX | XX]
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EX seconds
integer
Expire the key after this many seconds.
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PX milliseconds
integer
Expire the key after this many milliseconds.
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NX
flag
Only set the key if it does not already exist.
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XX
flag
Only set the key if it already exists.
SET session:abc "user42" EX 3600
# OK

SET counter 0 NX
# OK  (set, key was absent)

SET counter 0 NX
# (nil)  (not set, key already exists)
Returns: OK on success. Nil when the NX or XX condition is not met.

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GETSET

Atomically sets key to a new value and returns the previous value stored at that key. Useful for implementing atomic swap patterns. Syntax: GETSET key value 
SET token "old-token"
GETSET token "new-token"
# "old-token"

GET token
# "new-token"
Returns: Bulk string containing the old value, or nil if the key did not exist before the call.

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APPEND

Appends value to the end of the string stored at key. If key does not exist, it is created as an empty string first. Syntax: APPEND key value 
APPEND log "2024-01-01: server started\n"
# (integer) 27

APPEND log "2024-01-01: request received\n"
# (integer) 57
Returns: Integer — the new byte length of the string after the append.

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STRLEN

Returns the byte length of the string stored at key. Syntax: STRLEN key 
SET name "Alice"
STRLEN name
# (integer) 5

STRLEN nonexistent
# (integer) 0
Returns: Integer — the length in bytes, or 0 if the key does not exist.

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GETRANGE

Returns a substring of the string stored at key, between the start and end byte offsets (both inclusive). Negative indices count from the end: -1 is the last byte, -2 the second-to-last, and so on. Syntax: GETRANGE key start end 
SET msg "Hello, World!"
GETRANGE msg 0 4
# "Hello"

GETRANGE msg -6 -1
# "World!"
Returns: Bulk string — the substring. Returns an empty string if the key does not exist or the range is invalid.

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SETRANGE

Overwrites part of the string stored at key, beginning at offset. Zero-pads the string if the offset extends past the current length. The offset must be non-negative. Syntax: SETRANGE key offset value 
SET greeting "Hello World"
SETRANGE greeting 6 "Cache"
# (integer) 11

GET greeting
# "Hello Cache"
Returns: Integer — the new byte length of the string after the overwrite.

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INCR

Increments the integer value stored at key by 1. If the key does not exist, it is initialised to 0 before incrementing. Returns an error if the value is not a valid integer. Syntax: INCR key 
SET page_views 100
INCR page_views
# (integer) 101

INCR new_counter
# (integer) 1
Returns: Integer — the new value after incrementing.

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DECR

Decrements the integer value stored at key by 1. Behaves like INCR in reverse; initialises to 0 if the key does not exist. Syntax: DECR key 
SET stock 5
DECR stock
# (integer) 4
Returns: Integer — the new value after decrementing.

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INCRBY

Increments the integer value stored at key by the given delta. Syntax: INCRBY key delta 
SET score 50
INCRBY score 25
# (integer) 75
Returns: Integer — the new value after incrementing.

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DECRBY

Decrements the integer value stored at key by the given delta. Syntax: DECRBY key delta 
SET balance 200
DECRBY balance 30
# (integer) 170
Returns: Integer — the new value after decrementing.

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MGET

Returns the values of all specified keys in order. For any key that does not exist or holds a non-string type, nil is returned in that position. Syntax: MGET key [key ...] 
SET user:1:name "Alice"
SET user:2:name "Bob"

MGET user:1:name user:2:name user:3:name
# 1) "Alice"
# 2) "Bob"
# 3) (nil)
Returns: Array of bulk strings (or nil entries) in the same order as the requested keys.

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MSET

Sets multiple key-value pairs in a single atomic call. Existing keys are overwritten. Unlike SET, MSET has no conditional options. Syntax: MSET key value [key value ...] 
MSET user:1:name "Alice" user:1:age "30" user:1:city "Berlin"
# OK

MGET user:1:name user:1:age user:1:city
# 1) "Alice"
# 2) "30"
# 3) "Berlin"
Returns: Always OK.
Use MSET and MGET to batch reads and writes into a single round-trip, reducing client latency when working with related keys.