clj-ttldb

A wrapper around RocksDB with Time to live (TTL) support based on the TtlDB class, provided by RocksDB Java API.

The source code and the documentation is based on rotyo/clj-rocksdb library.

Basic Usage

[org.clojars.vaugusto92/clj-ttldb "0.1.0"]

To create or access a database, use clj-ttldb/create-db: The returned database object can be used with clj-ttldb/get, put, delete, batch, and iterator. RocksDB by default stores the keys and values in byte arrays. We may want to define custom encoders and decoders. This can be done in create-db:

Notice that the value returned is a byte-array. This is because byte arrays are the native storage format for RocksDB, and we haven't defined custom encoders and decoders. This can be done in create-db:

;; A map with options (at least :create-if-missing?)
;; {:key-decoder
;;  :key-encoder
;;  :val-decoder
;;  :val-encoder
;;  :create-if-missing?
;;  :error-if-exists?
;;  :write-buffer-size
;;  :block-size
;;  :max-open-files
;;  :cache-size
;;  :comparator
;;  :compress?
;;  :paranoid-checks?
;;  :block-restart-interval
;;  :logger}
clj-ttldb> (def options {:create-if-missing? true})

;; Time to live in seconds
clj-ttldb> (def ttl 1000)

;; open the database with write option
clj-ttldb> (def readonly? false) 

clj-ttldb> (def db (create-db "/tmp/rocksdb" 
                              options
                              ttl
                              readonly?))
#'clj-ttldb/db
clj-ttldb> (put db "a" "b")
nil
clj-ttldb> (get db "a")
"b"

Both put and delete can take multiple values, which will be written in batch:

clj-ttldb> (put db "a" "b" "c" "d" "e" "f")
nil
clj-ttldb> (delete db "a" "c" "e")
nil

If you need to batch a collection of puts and deletes, use batch:

clj-ttldb> (batch db {:put ["a" "b" "c" "d"] :delete ["j" "k" "l"]})

Syncing writes to disk can be forced via sync, and compaction can be forced via compact.

License

EPL-v1.0 Distributed under the Eclipse Public License, the same as Clojure.