kona

It is a project created to manage various key-value stores.
Currently, only RocksDB is supported, but we will continue to increase the number of key-value stores that can be supported.

Prerequisite

• python >= 3.8

Supported Key-Value Store

• RocksDB v6.26.1
• LMDB v1.4.x

Installation

$ pip install kona

Example

from kona.key_value_store import KeyValueStore

db = KeyValueStore.new(
    'file://./key_value_store_test_database',
    store_type='rocksdb',
    create_if_missing=True
)

db.put(b'foo', b'bar')
print(db.get(b'foo'))
db.close()
db.destroy_store()

# Result
# b'bar'

Batch

You can write to DataBase at a specific point in time using WriteBatch().

from kona.key_value_store import KeyValueStore

db = KeyValueStore.new(
    'file://./key_value_store_test_database',
    store_type='rocksdb',
    create_if_missing=True
)

batch = db.WriteBatch()

batch.put(b'test_key_1', b'test_value_1')
batch.put(b'test_key_2', b'test_value_2')

batch.write()

print(db.get(b'test_key_1'))
print(db.get(b'test_key_2'))

db.destroy_store()

# Result
# b'test_value_1'
# b'test_value_2'

CancelableBatch

You can cancel data written in batches using CancelableWriteBatch().

from kona.key_value_store import KeyValueStore

db = KeyValueStore.new(
    'file://./key_value_store_test_database',
    store_type='rocksdb',
    create_if_missing=True
)

test_items = {
    b'test_key_1': b'test_value_1',
    b'test_key_2': b'test_value_2',
    b'test_key_3': b'test_value_3',
    b'test_key_4': b'test_value_4',
    b'test_key_5': b'test_value_5',
}

for key, value in test_items.items():
    db.put(key, value)

cancelable_batch = db.CancelableWriteBatch()
cancelable_batch.put(b'cancelable_key_1', b'cancelable_value_1')
cancelable_batch.put(b'test_key_2', b'edited_test_value_2')
cancelable_batch.put(b'cancelable_key_2', b'cancelable_value_2')
cancelable_batch.put(b'test_key_4', b'edited_test_value_4')
cancelable_batch.write()

for key, value in db.Iterator():
    print(f'Before Cancel: key={key}, value={value}')

cancelable_batch.cancel()

for key, value in db.Iterator():
    print(f'After Cancel: key={key}, value={value}')

db.destroy_store()

# Before Cancel
# Before Cancel: key=b'cancelable_key_1', value=b'cancelable_value_1'
# Before Cancel: key=b'cancelable_key_2', value=b'cancelable_value_2'
# Before Cancel: key=b'test_key_1', value=b'test_value_1'
# Before Cancel: key=b'test_key_2', value=b'edited_test_value_2'
# Before Cancel: key=b'test_key_3', value=b'test_value_3'
# Before Cancel: key=b'test_key_4', value=b'edited_test_value_4'
# Before Cancel: key=b'test_key_5', value=b'test_value_5'

# After Cancel
# After Cancel: key=b'test_key_1', value=b'test_value_1'
# After Cancel: key=b'test_key_2', value=b'test_value_2'
# After Cancel: key=b'test_key_3', value=b'test_value_3'
# After Cancel: key=b'test_key_4', value=b'test_value_4'
# After Cancel: key=b'test_key_5', value=b'test_value_5'

Benchmark

You can run the benchmark with the following command

$ benchmark

LMDB Options

As a result of our benchmarks, we found the following lmdb options for performance. However, stability is under review and has not been reflected at this time. It will be provided for users to set in a future update. (LMDB Options)

writemap = True
map_async = True
sync = False

Log

Add the below configuration for loguru.

KONA_LOG_ENABLE_LOGGER=[true|false]