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 3.7.5
Supported Key-Value Store
- RocksDB
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'
