t44k/clj-rocksdb

clj-rocksdb

This is a self-contained wrapper around RocksDB, which provides all the necessary binaries via RocksDB Java API.

The source code and the documentation is hevaily based on Factual/clj-leveldb library.

basic usage

[kotyo/clj-rocksdb "0.1.6"]

To create or access a database, use clj-rocksdb/create-db: The returned database object can be used with clj-rocksdb/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:

clj-rocksdb> (def db (create-db "/tmp/rocksdb" 
                       {:key-encoder taoensso.nippy/freeze :key-decoder taoensso.nippy/thaw 
                        :val-encoder taoensso.nippy/freeze :val-decoder taoensso.nippy/thaw}))
#'clj-rocksdb/db
clj-rocksdb> (put db "a" "b")
nil
clj-rocksdb> (get db "a")
"b"

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

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

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

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

We can also get a sequence of all key/value pairs, either in the entire database or within a given range using iterator:

clj-rocksdb> (put db "a" "b" "c" "d" "e" "f")
nil
clj-rocksdb> (iterator db)
(["a" "b"] ["c" "d"] ["e" "f"])
clj-rocksdb> (iterator db "c" nil)
(["c" "d"] ["e" "f"])
clj-rocksdb> (iterator db nil "c")
(["a" "b"] ["c" "d"])

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

license

done by kotyo

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