https://github.com/vida-nyu/kvdb4j
A simple Java interface for multiple key-value databases.
https://github.com/vida-nyu/kvdb4j
Last synced: 3 months ago
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A simple Java interface for multiple key-value databases.
- Host: GitHub
- URL: https://github.com/vida-nyu/kvdb4j
- Owner: VIDA-NYU
- License: apache-2.0
- Created: 2021-10-15T22:51:35.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2022-07-10T21:47:14.000Z (almost 3 years ago)
- Last Synced: 2025-01-24T15:36:41.995Z (4 months ago)
- Language: Java
- Size: 88.9 KB
- Stars: 0
- Watchers: 8
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
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README
# KVDB4J
A simple Java interface for multiple key-value databases.
## Usage
#### Creating a key-value DB (KVDB) instance
The first step is to create a key-value DB instance. Currently,
[RocksDB](https://github.com/facebook/rocksdb/) and
[LevelDB](https://github.com/dain/leveldb) implementations are available.
```java
// RocksDB
boolean readOnly = false;
KVDB db = RocksDBBackend.create(path, readOnly);
// LevelDB
KVDB db = LevelDBBackend.create(path)
```
#### Storing and reading data
The KVDB interface only allows storing raw byte arrays. To store higher-level
data easily, the `StringObjectKVDB` class can be used to automatically serialize
and store Java objects. `StringObjectKVDB` we transform objects into bytes and
store them using the underlying `KVDB` implementation provided.
In the following example, objects are automatically serialized using the Kryo library:
```java
StringObjectKVDB odb = new StringObjectKVDB<>(db, new KryoIO<>(String.class));
odb.put("a", "1");
odb.put("b", "2");
assertEquals("1", odb.get("a"));
assertEquals("2", odb.get("b"));
try(CloseableIterator> it = odb.iterator()){
assertTrue(it.hasNext());
KV next;
next = it.next();
assertEquals("a", next.getKey());
assertEquals("1", next.getValue());
assertTrue(it.hasNext());
next = it.next();
assertEquals("b", next.getKey());
assertEquals("2", next.getValue());
assertFalse(it.hasNext());
assertNull(it.next());
} catch (Exception e) {
throw new RuntimeException("Failed to close the database iterator", e);
}
odb.close();
```
Instead of using Kryo serialization, users can configure custom
serialization strategies by providing an object that implements
the `IO` interface (`KryoIO` implements this interface).
#### KVDB for specific data types
Storing native data types is also possible using specialized classes:
- `StringIntKVDB`, key is `String` and value is `int`.
- `IntStringKVDB`, key is `int` and value is `String`.
- `BytesBytesKVDB`, key is `byte[]` and value is `byte[]`.
- `IntStringKVDB`, key is `int` and value is `String`.
- `StringObjectKVDB`, key is `String` and value is `Object`.