-
Notifications
You must be signed in to change notification settings - Fork 354
Deleting many rows from Cassandra
Turbo87 edited this page Oct 11, 2014
·
4 revisions
In case you need to delete many rows from Cassandra and cannot just drop and re-create your CF, then you can leverage the MutationBatch object. Here is an example of deleting many rows from a CF. We use a fixed batch size and just submit a bunch of MutationBatch tasks to a bounded threadpool.
private void deleteManyRows() {
final ColumnFamily<String, Long> cf =
new ColumnFamily<String, Long>("MyCF", StringSerializer.get(), LongSerializer.get());
final Keyspace ks = null; // Assume you have this
final Iterator<String> rowKeys = null; // Assume you have this built
int batchSize = 1000;
int nThreads = 10;
final ExecutorService threadPool = Executors.newFixedThreadPool(nThreads);
MutationBatch currentBatch = ks.prepareMutationBatch();
int currentBatchSize = 0;
while (rowKeys.hasNext()) {
String rowKey = rowKeys.next();
currentBatch.withRow(cf, rowKey).delete();
currentBatchSize++;
if (!rowKeys.hasNext() || (currentBatchSize > batchSize)) {
threadPool.submit(new MutationBatchExec(currentBatch));
currentBatch = ks.prepareMutationBatch();
currentBatchSize = 0;
}
}
}
private class MutationBatchExec implements Callable<Void> {
private final MutationBatch myBatch;
private MutationBatchExec(MutationBatch batch) {
myBatch = batch;
}
@Override
public Void call() throws Exception {
myBatch.execute();
return null;
}
}
A Netflix Original Production
Tech Blog | Twitter @NetflixOSS | Jobs
- Getting-Started
- Configuration
- Features
- Monitoring
- Thread Safety
- Timeouts
- Recipes
- Examples
- Javadoc
- Utilities
- Cassandra-Compatibility
- FAQ
- End-to-End Examples
- Astyanax Integration with Java Driver