On 2010-04-05 03:42, Paul Prescod wrote:
> On Sun, Apr 4, 2010 at 5:06 PM, Benjamin Black wrote:
>> ...
>>
>> Are you suggesting this would give you counter semantics?
>
> Yes: My understanding of cassandra-580 is that it gives you increment
> and decrement which are the basis of counters.
There
Dear all,
How can I flush all Commit Log for Cassandra version 042?
I use nodeprobe flush but It seem does not run.
Thank a lot for support.
--
Best regards,
JKnight
On Mon, Apr 5, 2010 at 12:01 AM, David Strauss wrote:
> On 2010-04-05 03:42, Paul Prescod wrote:
>...
>
> There is a difference between Cassandra allowing inc/dec on values and
> actually *knowing* the resultant value at the time of the write. It's
> likely that inc/dec support will still feature
On 2010-04-05 07:47, Paul Prescod wrote:
> On Mon, Apr 5, 2010 at 12:01 AM, David Strauss wrote:
>> On 2010-04-05 03:42, Paul Prescod wrote:
>> ...
>>
>> There is a difference between Cassandra allowing inc/dec on values and
>> actually *knowing* the resultant value at the time of the write. It's
Thanks for for reply, David.
I will tell more the detail about the system. My system is used to store the
score (point) user earn when they play game.
"Mark" is the score.
User's score changes when user win game, buy or sell anything.
Sorry I make a mistake. My data model is:
Mark{ //Column Fam
I need the question about monotonicity answered, too.
You should also know: Cassandra is not ideal for directly tracking
values you increment or decrement.
On 2010-04-05 08:04, JKnight JKnight wrote:
> Thanks for for reply, David.
>
> I will tell more the detail about the system. My system is us
Thanks David,
But what's does "monotonicity" mean?
User's score belongs to their action. When they win the game or sale
something, user's score will increase. When user lose the game or buy
something, user's score will decrease.
On Mon, Apr 5, 2010 at 4:09 AM, David Strauss wrote:
> I need the
Hello guys
I have a pretty similar task. There's a need to store tags of products
with score. Score may go up and down and tags have to be ordered by
their score for each product. Score is updated "very" often.
I was thinking of using the following model (simplified here for clarity):
Product =
If user scores move in more than one direction, as they apparently do in your
case, they are not monotonic. Monotonicity can make system design a bit easier
for various reasons.
- "JKnight JKnight" wrote:
Thanks David,
But what's does "monotonicity" mean?
User's score belongs to thei
In any case, the common approach to this in Cassandra is to not directly
manipulate the user's total score but to insert columns representing changes to
the score, later totaling them (and possibly inserting them elsewhere so you
get the automatic sort). There are many fancy ways to approach th
Cache the => map as you write values (a "write-through"
cache) so that reading the current score hits something like memcached instead
of Cassandra. With a cache hit, you get an ideal, write-only path in Cassandra.
Three blind writes in Cassandra is cheap -- no matter what your scale. The only
It makes sense.
Thanks, David!
On Mon, Apr 5, 2010 at 2:34 PM, David Timothy Strauss
wrote:
> Cache the => map as you write values (a
> "write-through" cache) so that reading the current score hits something like
> memcached instead of Cassandra. With a cache hit, you get an ideal,
> write-
It seems pretty clear to me that the full memcached protocol is not
appropriate for Cassandra. The question is whether some subset of it is of
any use to anybody. The only advantage I can see is that there are a large
number of clients out there that can speak it already; but any app that is
making
On Sat, 3 Apr 2010 13:52:22 -0700 Benjamin Black wrote:
BB> What happens if the IP I get back is for a seed that happens to be
BB> down right then? And then that IP is cached locally by my resolver?
You have to set the TTL to be the right number of seconds for your
environment. With tinydns o
On Sat, 3 Apr 2010 14:10:37 -0500 Jonathan Ellis wrote:
JE> IMO the "right" way to do it is to configure your machines so that
JE> autodetecting listenaddress Just Works, so you can deploy exactly the
JE> same config to all nodes.
It would be nice if Cassandra looked at all the available interf
Thanks for your help, David.
On Mon, Apr 5, 2010 at 7:25 PM, Andriy Bohdan wrote:
> It makes sense.
>
> Thanks, David!
>
> On Mon, Apr 5, 2010 at 2:34 PM, David Timothy Strauss
> wrote:
> > Cache the => map as you write values (a
> "write-through" cache) so that reading the current score hi
On Mon, Apr 5, 2010 at 1:02 AM, David Strauss wrote:
> ...
>
> But your "write then read" model lacks the atomicity of the memcached
> API. It's possible for two clients to read the same value.
Do you have an example application where this particular side effect
of eventual consistency is problem
On Mon, Apr 5, 2010 at 5:29 AM, Ryan Daum wrote:
> It seems pretty clear to me that the full memcached protocol is not
> appropriate for Cassandra. The question is whether some subset of it is of
> any use to anybody. The only advantage I can see is that there are a large
> number of clients out t
Are these applications using memcached for caching or for something else?
I don't see the point in putting Cassandra in as a level 1 or 2 cache
replacement? Especially given as it does not support any reasonable
expiration policy that would be of use in those circumstances.
Ryan
On Mon, Apr 5, 2
On Mon, Apr 5, 2010 at 10:19 AM, Ryan Daum wrote:
> Are these applications using memcached for caching or for something else?
> I don't see the point in putting Cassandra in as a level 1 or 2 cache
> replacement? Especially given as it does not support any reasonable
> expiration policy that would
>
> Here are a couple of example projects for info.
>
> Django:
>
> http://docs.djangoproject.com/en/dev/topics/cache/
>
> It says of "increment/decrement": "incr()/decr() methods are not
> guaranteed to be atomic. On those backends that support atomic
> increment/decrement (most notably, the memca
2010/4/5 Ted Zlatanov
> On Sat, 3 Apr 2010 14:10:37 -0500 Jonathan Ellis
> wrote:
>
> JE> IMO the "right" way to do it is to configure your machines so that
> JE> autodetecting listenaddress Just Works, so you can deploy exactly the
> JE> same config to all nodes.
>
> It would be nice if Cassand
On Mon, Apr 5, 2010 at 10:45 AM, Mike Malone wrote:
> ...
>
> FWIW, I added the atomic increment/decrement operations to the Django cache
> interface (and wrote that documentation) because the functionality was
> useful for large scale apps. I didn't implement atomic increment/decrement
> or atomi
On Mon, 5 Apr 2010 13:10:38 -0500 Brandon Williams wrote:
BW> 2010/4/5 Ted Zlatanov
>> It would be nice if Cassandra looked at all the available interfaces and
>> selected the one whose reverse DNS lookup returned ".*cassandra.*" (or
>> some keyword the user provided).
>>
>> In other words, wh
>
> That's useful information Mike. I am a bit curious about what the most
> common use cases are for atomic increment/decrement. I'm familiar with
> atomic add as a sort of locking mechanism.
>
They're useful for caching denormalized counts of things. Especially things
that change rapidly. Instea
On Mon, Apr 5, 2010 at 1:35 PM, Mike Malone wrote:
>> That's useful information Mike. I am a bit curious about what the most
>> common use cases are for atomic increment/decrement. I'm familiar with
>> atomic add as a sort of locking mechanism.
>
> They're useful for caching denormalized counts of
On Mon, Mar 29, 2010 at 6:42 PM, Tatu Saloranta wrote:
> Perhaps it would be good to have convenience workflow for replacing
> broken host ("squashing lemons")? I would assume that most common use
> case is to effectively replace host that can't be repaired (or perhaps
> it might sometimes be best
When you're saying you can check 50 or 100 per second, how many rows
and columns does a check involve? What query api are you using?
Your cassandra nodes look mostly idle. Is each client thread getting
the same amount of work or are some finishing sooner than others? Is
your client cpu or disk
On Fri, Apr 2, 2010 at 10:06 AM, S Ahmed wrote:
> Greetings!
>
> Content management systems usually have complex sort operations, how would
> this be best handled with Cassandra?
>
> Is the only way to handle this type of situation to build indexes for each
> and every sort?
>
> example model:
>
Usually sudden heap jumps involve compacting large rows.
0.6 (since beta3) includes a warning log when it finishes compacts a
row over 500MB by default, in the hopes that this will give you enough
time to fix things before whatever is making large rows makes one too
large to fit in memory.
On Fri
Short answer: upgrade to 0.6.
On Sat, Apr 3, 2010 at 7:56 AM, Anty wrote:
> Does anyone have solve the problem?I encounter the same error too.
>
> On Mon, Mar 29, 2010 at 12:12 AM, Benoit Perroud wrote:
>>
>> I got the same error when the nodes are using lot of I/O, i.e during
>> compaction.
>>
Cool, you should add it to
http://wiki.apache.org/cassandra/ClientOptions. (Click Login to get a
sign up page.)
On Sat, Apr 3, 2010 at 11:38 AM, Chris Shorrock wrote:
> For the past week or so I've been developing (another) Scala based high
> level Cassandra client - Cascal. While I know there's
On Mon, Apr 5, 2010 at 1:46 PM, Paul Prescod wrote:
> On Mon, Apr 5, 2010 at 1:35 PM, Mike Malone wrote:
> >> That's useful information Mike. I am a bit curious about what the most
> >> common use cases are for atomic increment/decrement. I'm familiar with
> >> atomic add as a sort of locking me
You'll have to give a more detailed error. "nodeprobe flush" is
exactly what you should be trying.
On Mon, Apr 5, 2010 at 2:37 AM, JKnight JKnight wrote:
> Dear all,
>
> How can I flush all Commit Log for Cassandra version 042?
> I use nodeprobe flush but It seem does not run.
>
> Thank a lot fo
On Sat, Apr 3, 2010 at 12:12 PM, Matthew Chambers
wrote:
> Your git page looks great, I like your cassandra explanation and graphic.
+1 on the docs - they're very nice. Off-topic, but what'd you use to create
that graphic?
Mike
Thanks guys - Will definitely toss mention of it in the Wiki..(the graphic
was created using http://yuml.me/ - Great tool for quickly throwing
something together using pretty simple syntax)
On Mon, Apr 5, 2010 at 2:43 PM, Mike Malone wrote:
> On Sat, Apr 3, 2010 at 12:12 PM, Matthew Chambers >
On 4/5/10 2:11 PM, Jonathan Ellis wrote:
On Mon, Mar 29, 2010 at 6:42 PM, Tatu Saloranta wrote:
Perhaps it would be good to have convenience workflow for replacing
broken host ("squashing lemons")? I would assume that most common use
[ snip ]
Does anyone have numbers on how badly "nodetool re
On Mon, Apr 5, 2010 at 5:20 PM, Rob Coli wrote:
> On 4/5/10 2:11 PM, Jonathan Ellis wrote:
>>
>> On Mon, Mar 29, 2010 at 6:42 PM, Tatu Saloranta
>> wrote:
>>>
>>> Perhaps it would be good to have convenience workflow for replacing
>>> broken host ("squashing lemons")? I would assume that most com
On Mon, Apr 5, 2010 at 1:46 PM, Paul Prescod wrote:
> On Mon, Apr 5, 2010 at 1:35 PM, Mike Malone wrote:
>>> That's useful information Mike. I am a bit curious about what the most
>>> common use cases are for atomic increment/decrement. I'm familiar with
>>> atomic add as a sort of locking mechan
Is there a generic GUI tool for viewing cassandra datastore? being able to
view and edit data from a GUI tool like oracle sqldeveloper is very useful.
-aj
On Mon, Apr 5, 2010 at 4:48 PM, Tatu Saloranta wrote:
> ...
>
> I would think that there is also possibility of losing some
> increments, or perhaps getting duplicate increments?
I believe that with vector clocks in Cassandra 0.7 you won't lose
anything. The conflict resolver will do the summatio
look at chiton on github.
On Tue, Apr 6, 2010 at 3:06 AM, AJ Chen wrote:
> Is there a generic GUI tool for viewing cassandra datastore? being able to
> view and edit data from a GUI tool like oracle sqldeveloper is very useful.
> -aj
>
--
Saygılar && İyi Çalışmalar
Timu EREN ( a.k.a selam )
Thanks Jonathan,
When I run "nodeprobe flush" with parameter -host is Cassandra server setup
on my computer, my computer is hang up by Cassandra. (When I kill all Java
process, the computer will work well)
Yesterday, when run "nodeprobe flush" on my live server, I didn't flush all
keyspace so tha
On Mon, Apr 5, 2010 at 9:11 PM, JKnight JKnight wrote:
> Thanks Jonathan,
>
> When I run "nodeprobe flush" with parameter -host is Cassandra server setup
> on my computer, my computer is hang up by Cassandra. (When I kill all Java
> process, the computer will work well)
Sounds like flush generate
Hi all,
I've just started experimenting with Cassandra to get a feel for the
system. I've set up a test cluster and to get a ballpark idea of its
performance I wrote a simple tool to load some toy data into the
system. Surprisingly, I am able to "overwhelm" my 4-node cluster with
writes from a sin
I just tried the same test with ConsistencyLevel.ALL, and the problem
went away - the writes are somewhat slower but the cluster never gets
into a bad state. So, I wonder if this is a bug in Cassandra's
handling of async / "non-ConsistencyLevel.ALL" writes ...
-- Ilya
On Mon, Apr 5, 2010 at 9:31
You are running out of memory on your nodes. Before the final crash
your nodes are probably slow due to GC. What is your memtable size?
What cache options did you configure?
On Tue, Apr 6, 2010 at 7:31 AM, Ilya Maykov wrote:
> Hi all,
>
> I've just started experimenting with Cassandra to get a f
I'm running the nodes with a JVM heap size of 6GB, and here are the
related options from my storage-conf.xml. As mentioned in the first
email, I left everything at the default value. I briefly googled
around for "Cassandra performance tuning" etc but haven't found a
definitive guide ... any help wi
Do you see one of the disks used by cassandra filled up when a node crashes?
On Tue, Apr 6, 2010 at 9:39 AM, Ilya Maykov wrote:
> I'm running the nodes with a JVM heap size of 6GB, and here are the
> related options from my storage-conf.xml. As mentioned in the first
> email, I left everything a
No, the disks on all nodes have about 750GB free space. Also as
mentioned in my follow-up email, writing with ConsistencyLevel.ALL
makes the slowdowns / crashes go away.
-- Ilya
On Mon, Apr 5, 2010 at 11:46 PM, Ran Tavory wrote:
> Do you see one of the disks used by cassandra filled up when a no
You are blowing away the mostly saner JVM_OPTS running it that way.
Edit cassandra.in.sh (or wherever config is on your system) to
increase mx to 4G (not 6G, for now) and leave everything else
untouched and do not specify JVM_OPTS on the command line. See if you
get the same behavior.
b
On Mon,
On Mon, Apr 5, 2010 at 5:10 PM, Paul Prescod wrote:
> On Mon, Apr 5, 2010 at 4:48 PM, Tatu Saloranta wrote:
>> ...
>>
>> I would think that there is also possibility of losing some
>> increments, or perhaps getting duplicate increments?
>
> I believe that with vector clocks in Cassandra 0.7 you w
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