# Kdb
This library integrates RocksDB as a persistent storage backend with ETS as an in-memory cache featuring configurable TTL (time-to-live) support. It is purpose-built for high-demand environments that require both rapid read performance and robust, fault-tolerant write operations.
By leveraging ETS for ultra-low-latency access and utilizing RocksDB for durable, disk-based storage, the system achieves a finely balanced architecture that handles heavy write loads without compromising speed or data integrity.
## Key Features
- Fast, TTL-enabled ETS layer for short-lived, memory-resident data.
- Reliable RocksDB persistence with efficient key-value write performance.
- Unified read/write interface with cache-first logic and optional async sync to disk.
- Configurable batching and write coalescing for high-throughput pipelines.
- Suitable for event processors, caching proxies, ephemeral data stores, and real-time systems under sustained load.
>Tested exclusively on Linux x86_64 systems (Ubuntu 22.04.3 LTS)
>Note: This library is under active development and evolving rapidly, with the goal of reaching a stable release at version v0.2.0. Contributions, testing, and feedback are welcome as the project matures toward production readiness
## Installation
The package can be installed by adding `kdb` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:kdb, "~> 0.1.0"}
]
end
```
## Roadmap
- [✅] Start
- [✅] Get & put
- [✅] Fetch & Access
- [✅] Batching
- [❌] TTL (No tested yet)
- [❌] Count keys
- [✅] Encoding/Decoding
- [✅] Streaming
- [✅] List
- [✅] Increment
- [✅] Decrement
- [✅] Delete
- [✅] Commit
- [✅] Close
- [❌] Backup & Restore
- [✍️] Testing
- [❌] Indexing
- [❌] Sharding
- [❌] Replication
- [❌] Benchmarking
- [❌] Documentation
## Usage
```elixir
# Create a bucket
defmodule MyBucket do
use Kdb.Bucket,
# atom or module, default module name
name: :my_bucket,
# default is true
ttl: true,
# default values
decoder: &Kdb.binary_to_term/1,
encoder: &Kdb.term_to_binary/1
end
# Start the Kdb database
{:ok, _sup} = Kdb.start_link(name: :dbname, folder: "database", buckets: [MyBucket])
# Get the database instance
kdb = Kdb.get(:dbname)
# Start/Get batch
kdb = Kdb.batch(kdb, "first batch")
# Get the bucket instance and the batch loaded inside
myb = Kdb.get_bucket(kdb, :my_bucket)
# Write data (batch is necessary for transactional operations)
MyBucket.put(myb, "key", "value")
MyBucket.put(myb, "mykey", 10)
MyBucket.put(myb, "mymap", %{a: 1, b: 2, c: 3})
MyBucket.put(myb, "mytuple", {3, 2, 1, :go})
MyBucket.incr(myb, "mykey", 12)
MyBucket.incr(myb, "mykey", -2)
# Read data
{:ok, "value"} = MyBucket.fetch(myb, "key")
myb["mykey"] == 20
"value" == MyBucket.get(myb, "key")
# Delete data
:ok = MyBucket.delete(myb, "key")
# Commit changes from first batch
:ok = Kdb.commit(kdb, "first batch")
# Transactional operations (memory isolation)
Kdb.transaction(kdb, fn kdb ->
myb = Kdb.get_bucket(kdb, :my_bucket)
Bucket.put(myb, "jess", 700)
Bucket.incr(myb, "carlos", 1000)
Bucket.put(myb, "jim", 950)
Bucket.put(myb, "caroline", 100)
Bucket.put(myb, "jony", 500)
end)
# List data
myb |> Enum.to_list() |> IO.inspect()
# Stream data
myb |> Kdb.Stream.stream() |> Enum.to_list() |> IO.inspect()
# Close the database
:ok = Kdb.close(kdb)
```
## Configuration
```elixir
# config/config.exs
config :myapp, :kdb,
name: :dbname,
folder: "database",
buckets: [MyBucket]
```
```elixir
# lib/application.ex
defmodule MyApp do
use Application
def start(_type, _args) do
children = [
{Kdb, Application.get_env(:myapp, :kdb)}
]
opts = [strategy: :one_for_one, name: MyApp.Supervisor]
Supervisor.start_link(children, opts)
end
end
```
## Testing
```bash
mix test test/kdb_test.exs
```
## License
This library is licensed under the MIT License.
