rocksdb.cr

RocksDB client for Crystal.

• crystal: 0.20.3 (at least 0.20.1 needed)

Supported API

See API

Installation

Add this to your application's shard.yml:

dependencies:
  rocksdb:
    github: maiha/rocksdb.cr
    version: 0.5.0

Usage

require "rocksdb"

db = RocksDB::DB.new("tmp/db1")

db.put("foo", "1")
db.get("foo")      # => "1"
db.delete("foo")

db.get("foo")      # => ""
db.get?("foo")     # => nil
db.get!("foo")     # raise RocksDB::NotFound.new("foo")

db.close

readonly mode

db = RocksDB::DB.new("tmp/db1", readonly: true)
# or RocksDB::DB.read("tmp/db1")
db.put("foo", "1")  # raise RocksDB::Error("Not supported operation in read only mode.")

Iterations

3.times{|i| db.put("k#{i}", i) }
db.keys            # => ["k0","k1","k2"]
db.keys(2)         # => ["k0","k1"]

db.each do |k,v|
  ...

Iterator

iter = db.new_iterator
iter.key           # => "k0"
iter.next
iter.value         # => "1"
iter.first
iter.key           # => "k0"
iter.seek("k2")
iter.next
iter.valid?        # => false

iter.close  # memory leaks when you forget this

• same as each

iter = db.new_iterator
iter.first
while (iter.valid?)
  # yield {iter.key, iter.value}
  iter.next
end  
iter.close  # memory leaks when you forget this

binary data

Although all data are stored as Binary in RocksDB, return value will be converted to String when accessed by String key.

db.put(Bytes[0], Bytes[9])
db.get(Bytes[0])  # => Bytes[9]
db.get("\u{0}")   # => "\t"

binary iterator

binary_XXX is available to treat data as binary

• binary_keys
• binary_each
• new_binary_iterator

db.keys        # => ["\t"]
db.binary_keys # => [Bytes[9]]

database options

• options for opening database
• read_options for reading data
• write_options for writing data

opts = RocksDB::Options.new
opts.set_create_if_missing(1)

ropts = RocksDB::ReadOptions.new
ropts.set_verify_checksum(1)

wopts = RocksDB::WriteOptions.new
wopts.set_sync(1)
wopts.disable_wal(1)

db = RocksDB::DB.new("tmp/db1", options: opts, read_options: ropts, write_options: wopts)

• all options: options.cr

Roadmap

0.5.0

• [x] Iterations for Binary

Testing

• Manual test has passed in local with librocksdb-dev
• Unfortunately, we can't run ci on TravisCI which doesn't support ubuntu-16.04.

Contributing

1. Fork it ( https://github.com/maiha/rocksdb.cr/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• maiha maiha - creator, maintainer