RE: cassandra reads are unbalanced

: Jack Krupansky [mailto:jack.krupan...@gmail.com] Sent: 04 December 2015 16:46 To: user@cassandra.apache.org Subject: Re: cassandra reads are unbalanced Thanks for the elaboration. A few more questions... Is there only a single thread in each client or are there multiple threads doing reading in

Re: cassandra reads are unbalanced

> > We monitor the number of reads / writes of every table via the cassandra > JMX metrics. (cassandra.db.read_count) > > … > > -- > > We can only monitor in 1 hour moving window > > > > > > > > > > Maybe the other two nodes

RE: cassandra reads are unbalanced

casionally has net connectivity issues Unlikely seems its AWS From: Jack Krupansky [mailto:jack.krupan...@gmail.com] Sent: 03 December 2015 16:11 To: user@cassandra.apache.org Subject: Re: cassandra reads are unbalanced How many clients do you have performing reads? Is your load balance

Re: cassandra reads are unbalanced

om] > *Sent:* 02 December 2015 16:27 > > *To:* user@cassandra.apache.org > *Subject:* Re: cassandra reads are unbalanced > > > > If you're using the Java driver with LOCAL_ONE and the default load > balancing strategy (TokenAware wrapped on DCAwareRoundRobin), the > dri

RE: cassandra reads are unbalanced

: DuyHai Doan [mailto:doanduy...@gmail.com] Sent: 02 December 2015 16:27 To: user@cassandra.apache.org Subject: Re: cassandra reads are unbalanced If you're using the Java driver with LOCAL_ONE and the default load balancing strategy (TokenAware wrapped on DCAwareRoundRobin), the driver

Re: cassandra reads are unbalanced

ode 1 (DC2) = 2.06k (seeder) > > Node 2 (DC2) = 1.38k > > Node 3 (DC2) = 1.43k > > > > > > *From:* DuyHai Doan [mailto:doanduy...@gmail.com] > *Sent:* 02 December 2015 14:22 > *To:* user@cassandra.apache.org > *Subject:* Re: cassandra reads are unbalanced

RE: cassandra reads are unbalanced

December 2015 14:22 To: user@cassandra.apache.org Subject: Re: cassandra reads are unbalanced Which Consistency level do you use for reads ? ONE ? Are you reading from only DC1 or from both DC ? What is the LoadBalancingStrategy you have configured for your driver ? TokenAware wrapped on

Re: cassandra reads are unbalanced

Which Consistency level do you use for reads ? ONE ? Are you reading from only DC1 or from both DC ? What is the LoadBalancingStrategy you have configured for your driver ? TokenAware wrapped on DCAwareRoundRobin ? On Wed, Dec 2, 2015 at 3:36 PM, Walsh, Stephen wrote: > Hey all, > > > > Tha

cassandra reads are unbalanced

Hey all, Thanks for taking the time to help. So we have 6 cassandra nodes in 2 Data Centers. Both Data Centers have a replication of 3 - so all nodes have all the data. Over the last 2 days we've noticed that data reads / writes has shifted from balanced to unbalanced (Nodetool status still sho

Re: Cassandra Reads

It only reads till that column (a sequential scan, I believe) and do not read the whole row. It uses a row-level column index to reduce the amount of data read. Much more details at (first 2-3 are must-reads in fact): http://thelastpickle.com/blog/2011/07/04/Cassandra-Query-Plans.html http://www.d

Cassandra Reads

Folks, When I read Column(s) from a table, does Cassandra read only that column? Or, does it read the entire row into memory and then filters out the contents to send only the requested column(s) ?

Re: Logging Cassandra Reads/Writes

gt; Blair >> >> On Jul 9, 2013, at 12:50 PM, hajjat <[hidden >> email]<http://user/SendEmail.jtp?type=node&node=7588930&i=2>> >> wrote: >> >> > Blair, thanks for the clarification! My friend actually just told me the >> > same.. &g

Re: Logging Cassandra Reads/Writes

air > > On Jul 9, 2013, at 12:50 PM, hajjat wrote: > > > Blair, thanks for the clarification! My friend actually just told me the > > same.. > > > > Any idea on how to do logging?? > > > > Thanks! > > > > > > > > -- > > View

Re: Logging Cassandra Reads/Writes

ir, thanks for the clarification! My friend actually just told me the > > same.. > > > > Any idea on how to do logging?? > > > > Thanks! > > > > > > > > -- > > View this message in context: > http://cassandra-user-incubator-apache-or

Re: Logging Cassandra Reads/Writes

; -- > View this message in context: > http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Logging-Cassandra-Reads-Writes-tp7588893p7588896.html > Sent from the cassandra-u...@incubator.apache.org mailing list archive at > Nabble.com. >

Re: Logging Cassandra Reads/Writes

Blair, thanks for the clarification! My friend actually just told me the same.. Any idea on how to do logging?? Thanks! -- View this message in context: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Logging-Cassandra-Reads-Writes-tp7588893p7588896.html Sent from the

Re: Logging Cassandra Reads/Writes

On 07/09/2013 12:25 PM, hajjat wrote: Hi, In a quorum read, my understanding is that Cassandra gets a digest of the object to be read from all nodes, and then chooses the fastest node for retrieving the data (if the quorum is met). According to this talk at Cassandra summit, that's incorrect.

Logging Cassandra Reads/Writes

possible to log the different delays involved in each operation-- for example, 0.1 seconds to get digests from all nodes, 1 second to transfer data, etc.? Thanks, Mohammad Hajjat -- View this message in context: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Logging-Cassandra

Re: : Cassandra reads under write-only load, read degradation after massive writes

Indexed columns cause read before write so that the index can be updated if the column already exists. On 11/09/2011 02:46 PM, Oleg Tsernetsov wrote: When monitoring JMX metrics of cassandra 0.8.7 loaded by write-only test I observe significant read activity on column family where I write to.

: Cassandra reads under write-only load, read degradation after massive writes

When monitoring JMX metrics of cassandra 0.8.7 loaded by write-only test I observe significant read activity on column family where I write to. It seems strange to me, but I expected no read activity on write-only load. The read activity is caused by writes, as when I stop the write test, reads act

Re: Questions about Cassandra reads

Thanks for the update, that is very useful! On Tue, Jul 12, 2011 at 3:16 PM, Philippe wrote: > Hi Jonathan, > Thanks for the answer, I wanted to report on the improvements I got because > someone else is bound to run into the same questions... > >> >> > C) I want to access a key that is at the 50

Re: Questions about Cassandra reads

Hi Jonathan, Thanks for the answer, I wanted to report on the improvements I got because someone else is bound to run into the same questions... > > C) I want to access a key that is at the 50th position in that table, > > Cassandra will seek position 0 and then do a sequential read of the file >

Re: Questions about Cassandra reads

Ah, I get it. Your normal access pattern should be one row at a time. On Sun, Jul 3, 2011 at 11:41 AM, David Boxenhorn wrote: >>> What do you think ? >> >> I think you should strongly consider denormalizing so that you can >> read ranges from a single row instead. > > Why do you recommend denorma

Re: Questions about Cassandra reads

>> What do you think ? > > I think you should strongly consider denormalizing so that you can > read ranges from a single row instead. Why do you recommend denormalizing instead of secondary indexes?

Re: Questions about Cassandra reads

On Fri, Jun 24, 2011 at 3:58 PM, Philippe wrote: > A) Upon opening an SSTTable for read, Cassandra samples one key in 100 to > speed up disk access. Close enough. > Is the percentage configurable ? # The Index Interval determines how large the sampling of row keys # is for a given SSTable. The

Questions about Cassandra reads

Hello, I am trying to understand the way cassandra reads data. I've been reading a lot and here is what I understand. Can I get some feedback on the following claims ? Which are right and which are wrong? A) Upon opening an SSTTable for read, Cassandra samples one key in 100 to speed up