That is the order I would expect to find if I read the CF, but if I do, I obtain (with any client or library I've tried):What happens if you export sstables with sstable2json ?Put some logging in Memtable.FlushRunnable.writeSortedContents to see the order the rows are writtenCheersOn 28/03/2013, at 5:05 AM, Carlos Pérez Miguel <email@example.com> wrote:Thanks, Lanny. That is what I am doing.Let's suppouse that I have a Users CF where each row represents a user in a cluster of 1 node. Rows are ordered by TimeUUID. I create some users in the next order:
Actually I'm having another problem. My UUIDOrderedPartitioner doesn't order by time. Instead, it orders by byte order and I cannot find why. Which are the functions that control ordering between tokens? I have implemented time ordering in the "compareTo" function of my UUID token class, but it seems that Cassandra is ignoring it. For example:
user a created with user_id: eac850fa-96f4-11e2-9f22-72ad6af0e500
user b created with user_id: f17f9ae8-96f4-11e2-98aa-421151417092
user c created with user_id: f82fccfa-96f4-11e2-8d99-26f8461d074c
user d created with user_id: fee21cec-96f4-11e2-945b-f9a2a2e32308
user e created with user_id: 058ec180-96f5-11e2-8c88-4aaf94e4f04e
user f created with user_id: 0c5032ba-96f5-11e2-95a5-60a128c0b3f4
user g created with user_id: 13036b86-96f5-11e2-80dd-566654c686cb
user h created with user_id: 19b245f6-96f5-11e2-9c8f-b315f455e5e0
That is the order I would expect to find if I read the CF, but if I do, I obtain (with any client or library I've tried):
user_id: 058ec180-96f5-11e2-8c88-4aaf94e4f04e name:"e"
user_id: 0c5032ba-96f5-11e2-95a5-60a128c0b3f4 name:"f"
user_id: 13036b86-96f5-11e2-80dd-566654c686cb name:"g"
user_id: 19b245f6-96f5-11e2-9c8f-b315f455e5e0 name:"h"
user_id: eac850fa-96f4-11e2-9f22-72ad6af0e500 name:"a"
user_id: f17f9ae8-96f4-11e2-98aa-421151417092 name:"b"
user_id: f82fccfa-96f4-11e2-8d99-26f8461d074c name:"c"
user_id: fee21cec-96f4-11e2-945b-f9a2a2e32308 name:"d"
Any idea what's happening?
Carlos Pérez Miguel2013/3/27 Lanny Ripple <firstname.lastname@example.org>Ah. TimeUUID. Not as useful for you then but still something for the toolbox.
On Mar 27, 2013, at 8:42 AM, Lanny Ripple <email@example.com> wrote:
> A type 4 UUID can be created from two Longs. You could MD5 your strings giving you 128 hashed bits and then make UUIDs out of that. Using Scala:
> import java.nio.ByteBuffer
> import java.security.MessageDigest
> import java.util.UUID
> val key = "Hello, World!"
> val md = MessageDigest.getInstance("MD5")
> val dig = md.digest(key.getBytes("UTF-8"))
> val bb = ByteBuffer.wrap(dig)
> val msb = bb.getLong
> val lsb = bb.getLong
> val uuid = new UUID(msb, lsb)
> On Mar 26, 2013, at 3:22 PM, aaron morton <firstname.lastname@example.org> wrote:
>>> Any idea?
>> Not off the top of my head.
>> Aaron Morton
>> Freelance Cassandra Consultant
>> New Zealand
>> On 26/03/2013, at 2:13 AM, Carlos Pérez Miguel <email@example.com> wrote:
>>> Yes it does. Thank you Aaron.
>>> Now I realized that the system keyspace uses string as keys, like "Ring" or "ClusterName", and I don't know how to convert these type of keys into UUID. Any idea?
>>> Carlos Pérez Miguel
>>> 2013/3/25 aaron morton <firstname.lastname@example.org>
>>> The best thing to do is start with a look at ByteOrderedPartitoner and AbstractByteOrderedPartitioner.
>>> You'll want to create a new TimeUUIDToken extends Token<UUID> and a new UUIDPartitioner that extends AbstractPartitioner<>
>>> Usual disclaimer that ordered partitioners cause problems with load balancing.
>>> Hope that helps.
>>> Aaron Morton
>>> Freelance Cassandra Consultant
>>> New Zealand
>>> On 25/03/2013, at 1:12 AM, Carlos Pérez Miguel <email@example.com> wrote:
>>>> I store in my system rows where the key is a UUID version1, TimeUUID. I would like to maintain rows ordered by time. I know that in this case, it is recomended to use an external CF where column names are UUID ordered by time. But in my use case this is not possible, so I would like to use a custom Partitioner in order to do this. If I use ByteOrderedPartitioner rows are not correctly ordered because of the way a UUID stores the timestamp. What is needed in order to implement my own Partitioner?
>>>> Thank you.
>>>> Carlos Pérez Miguel