hector

Right now, I have to manually generate the composite key by formatting the subkeys together. It's ugly and not efficient. I wonder if Hector provides such set of APIs to handle composite keys in a more decent way. yes it does. You can look at DynamicCompositeTest for examples: https://github.com/rantav/hector/blob/master/core/src/test/java/me/prettyprint/hector/api/beans/DynamicCompositeTest.java @Test public void allTypesSerialize() { DynamicComposite composite = new DynamicComposite(); UUID lexUUID = UUID.randomUUID(); com.eaio.uuid.UUID timeUUID = new com.eaio.uuid.UUID(); //add all forward

I'm using Hectors EmbeddedServerHelper to set up embedded Cassandra. It has teardown() and cleanup() methods. The problem is that cleanup method cannot delete some commit log files created by cassandra. Probably because there are still some cassandra daemons that were not properly shut down by the teardown() method. Here us the setup and teardown code: @BeforeClass public static void setUpBeforeClass() throws Exception { EmbeddedServerHelper sh = new EmbeddedServerHelper(); sh.setup(); } @AfterClass public static void tearDownAfterClass() throws Exception { EmbeddedServerHelper.teardown();

Using hector (cassandra client) when I try to do delete, it deletes the columns…but leaves the row key behind…does anyone know why, and how can I delete that row key as well ? This is expected when using Cassandra. Since it deletes by writing tombstones the data is still there until the next compaction. Eventually it will go a way completely, but your application code must be aware that an empty row is the same as a deleted row. Patricio Actually, it will go away in the next compaction that happens after the grace period for that row. Check this out: Wikipedia 来源： https://stackoverflow.com

We are doing the following to update the value of a counter, now we wonder if there is a straightforward way to get back the updated counter value immediately. mutator.incrementCounter(rowid1, "cf1", "counter1", value); Wildfire There's no single 'incrementAndGet' operation in Cassandra thrift API. Counters in Cassandra are eventually consistent and non-atomic. Fragile ConsistencyLevel.ALL operation is required to get "guaranteed to be updated" counter value, i.e. perform consistent read. ConsistencyLevel.QUORUM is not sufficient (as specified in counters design document: https://issues.apache

I am running into an issue "me.prettyprint.hector.api.exceptions.HUnavailableException: : May not be enough replicas present to handle consistency level." when I have RF=1, Read Consistency Level = 1 and one of the nodes in 6 node ring/ cluster is down. All of my reads are failing with this exception. Any idea? Ideally only reads that are looking for data in the node which is down should fail and all other reads should be successful? There could be a few possibilities: You're running a multi-row query (get_range, get_indexed_slices, multiget, or the cql equivalents) that requires multiple

How does a Cassandra Secondary-Index work internally? The docs state it is some kind of Hash Index: Given i have the colum username="foobar" (Column username will be scondary index) in a CF User with RandomOrderingPartitioner Is my asumption correct, that cassandra uses a "Distributed Hash Index" (=so the index is not on one single node=the index is splitted)? On how many nodes are the index-parts held (the same amout as the replicatio factor)? On which nodes are the index-parts held (does Cassandra split the index by the same logic as the key with RandomOrderingPartitioner)? In case the index

I have a row of counters and I want to get its' columns sorted by values. Is there any strategies or data models for that? I'm afraid there is no way of having Cassandra do this for you; you will need to get the entire row from Cassandra (paging for large rows) and sort it in the client. You could use a periodic MapReduce job to do this for you, and cache the result of the job back into Cassandra, if your solution can cope with non-uptodate results. 来源： https://stackoverflow.com/questions/8428364/how-to-get-sorted-counters-from-cassandra