🔑 Core Key-Value Commands

KacheDB implements the standard Redis / Valkey RESP2 and RESP3 binary wire protocol for standard key-value operations. All keys and values are treated as raw byte slices (&[u8]) and stored with zero heap allocation overhead inside 64-byte aligned Megaslab slots.

📋 Command Summary

Command	Syntax	Complexity	Description
`PING`	`PING [message]`	`O(1)`	Tests server liveness; returns `PONG` or echoed message.
`GET`	`GET key`	`O(1)`	Retrieves binary value; returns `nil` if missing or expired.
`SET`	`SET key value [EX seconds] [PX millis]`	`O(1)`	Stores binary value with optional TTL expiration.
`MGET`	`MGET key [key ...]`	`O(N)`	Batch retrieves multiple keys in a single pipelined operation.
`MSET`	`MSET key value [key value ...]`	`O(N)`	Atomically stores multiple key-value pairs.
`DEL`	`DEL key [key ...]`	`O(N)`	Deletes keys and immediately frees Megaslab slots.
`EXISTS`	`EXISTS key [key ...]`	`O(N)`	Returns the count of existing, unexpired keys.
`INCR`	`INCR key`	`O(1)`	Atomically increments string integer value by 1.
`DECR`	`DECR key`	`O(1)`	Atomically decrements string integer value by 1.
`INCRBY`	`INCRBY key delta`	`O(1)`	Atomically increments string integer value by `delta`.
`DECRBY`	`DECRBY key delta`	`O(1)`	Atomically decrements string integer value by `delta`.
`APPEND`	`APPEND key value`	`O(1)`	Appends `value` to existing string, returning new byte length.
`STRLEN`	`STRLEN key`	`O(1)`	Returns length of string value in bytes (0 if missing).
`DBSIZE`	`DBSIZE`	`O(1)`	Returns the total number of stored keys in the database.
`TYPE`	`TYPE key`	`O(1)`	Returns the string representation of the key's type (`string`, `vector`, or `none`).
`FLUSHDB`	`FLUSHDB`	`O(N)`	Removes all keys from the currently selected database.
`FLUSHALL`	`FLUSHALL`	`O(N)`	Removes all keys from all databases and resets Megaslab allocators.

🛠️ Detailed Command Reference & Examples

`SET` & `GET`

Stores and retrieves binary-safe values up to 2 MB per slot.

Syntax

SET key value [EX seconds] [PX milliseconds]
GET key

`kachedb-cli` Example

127.0.0.1:6379> SET user:100 "Alice"
OK

127.0.0.1:6379> GET user:100
"Alice"

127.0.0.1:6379> SET session:temp "abc123xyz" EX 30
OK

127.0.0.1:6379> GET missing_key
(nil)

Python SDK Example

with KacheClient() as client:
    client.set("user:100", "Alice")
    val = client.get("user:100")  # b'Alice'

`MSET` & `MGET`

Batch operations that store and retrieve multiple keys in a single network round-trip.

Syntax

MSET key value [key value ...]
MGET key [key ...]

`kachedb-cli` Example

127.0.0.1:6379> MSET config:theme "dark" config:lang "en" config:tz "UTC"
OK

127.0.0.1:6379> MGET config:theme config:lang config:missing config:tz
1) "dark"
2) "en"
3) (nil)
4) "UTC"

`INCR`, `DECR`, `INCRBY`, `DECRBY`

Atomic integer arithmetic executed in-place on string values. If the key does not exist, it is initialized to 0 before applying the operation.

Syntax

INCR key
DECR key
INCRBY key delta
DECRBY key delta

`kachedb-cli` Example

127.0.0.1:6379> INCR page_views
(integer) 1

127.0.0.1:6379> INCRBY page_views 100
(integer) 101

127.0.0.1:6379> DECR page_views
(integer) 100

127.0.0.1:6379> DECRBY page_views 50
(integer) 50

`APPEND` & `STRLEN`

String manipulation and length inspection.

Syntax

APPEND key value
STRLEN key

`kachedb-cli` Example

127.0.0.1:6379> SET doc:title "KacheDB"
OK

127.0.0.1:6379> APPEND doc:title " Architecture"
(integer) 20

127.0.0.1:6379> GET doc:title
"KacheDB Architecture"

127.0.0.1:6379> STRLEN doc:title
(integer) 20

`DEL` & `EXISTS`

Key deletion and existence verification.

Syntax

DEL key [key ...]
EXISTS key [key ...]

`kachedb-cli` Example

127.0.0.1:6379> EXISTS user:1 user:2
(integer) 1

127.0.0.1:6379> DEL user:1 user:2
(integer) 1

127.0.0.1:6379> EXISTS user:1
(integer) 0

`DBSIZE`

Returns the count of active, unexpired keys stored in the database.

Syntax

DBSIZE

`kachedb-cli` Example

127.0.0.1:6379> SET k1 "v1"
OK
127.0.0.1:6379> SET k2 "v2"
OK
127.0.0.1:6379> DBSIZE
(integer) 2

`TYPE`

Returns the underlying data structure type of the specified key.

Syntax

TYPE key

`kachedb-cli` Example

127.0.0.1:6379> SET greeting "hello"
OK
127.0.0.1:6379> TYPE greeting
string

127.0.0.1:6379> TYPE nonexistent
none

`FLUSHDB` & `FLUSHALL`

Deletes all keys in the database and recycles Megaslab blocks back to the free-list.

Syntax

FLUSHDB
FLUSHALL

`kachedb-cli` Example

127.0.0.1:6379> DBSIZE
(integer) 1000
127.0.0.1:6379> FLUSHDB
OK
127.0.0.1:6379> DBSIZE
(integer) 0

KacheDB Documentation