rocksdb/java/RocksDBColumnFamilySample.java

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// Copyright (c) 2014, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
import org.rocksdb.*;
import java.util.ArrayList;
import java.util.List;
public class RocksDBColumnFamilySample {
static {
RocksDB.loadLibrary();
}
public static void main(String[] args) throws RocksDBException {
if (args.length < 1) {
System.out.println(
"usage: RocksDBColumnFamilySample db_path");
return;
}
String db_path = args[0];
System.out.println("RocksDBColumnFamilySample");
RocksDB db = null;
Options options = null;
ColumnFamilyHandle columnFamilyHandle = null;
WriteBatch wb = null;
try {
options = new Options().setCreateIfMissing(true);
db = RocksDB.open(options, db_path);
assert(db != null);
// create column family
columnFamilyHandle = db.createColumnFamily(
new ColumnFamilyDescriptor("new_cf", new ColumnFamilyOptions()));
assert(columnFamilyHandle != null);
} finally {
if (columnFamilyHandle != null) {
columnFamilyHandle.dispose();
}
if (db != null) {
db.close();
db = null;
}
}
// open DB with two column families
List<ColumnFamilyDescriptor> columnFamilyDescriptors = new ArrayList<>();
// have to open default column family
columnFamilyDescriptors.add(new ColumnFamilyDescriptor(
RocksDB.DEFAULT_COLUMN_FAMILY, new ColumnFamilyOptions()));
// open the new one, too
columnFamilyDescriptors.add(new ColumnFamilyDescriptor(
"new_cf", new ColumnFamilyOptions()));
List<ColumnFamilyHandle> columnFamilyHandles = new ArrayList<>();
try {
db = RocksDB.open(new DBOptions(), db_path,
columnFamilyDescriptors, columnFamilyHandles);
assert(db != null);
// put and get from non-default column family
db.put(columnFamilyHandles.get(0), new WriteOptions(),
"key".getBytes(), "value".getBytes());
String value = new String(db.get(columnFamilyHandles.get(0),
"key".getBytes()));
// atomic write
wb = new WriteBatch();
wb.put(columnFamilyHandles.get(0), "key2".getBytes(), "value2".getBytes());
wb.put(columnFamilyHandles.get(1), "key3".getBytes(), "value3".getBytes());
wb.remove(columnFamilyHandles.get(0), "key".getBytes());
db.write(new WriteOptions(), wb);
// drop column family
db.dropColumnFamily(columnFamilyHandles.get(1));
} finally {
for (ColumnFamilyHandle handle : columnFamilyHandles){
handle.dispose();
}
if (db != null) {
db.close();
}
if (wb != null) {
wb.dispose();
}
}
}
}