Hi
I see in the log of my node cassandra that the parameter -XX:HeapDumpPath
is charged two times.
INFO [main] 2016-10-03 04:21:29,941 CassandraDaemon.java:205 - JVM
Arguments: [-ea, -javaagent:/usr/share/cassandra/lib/jamm-0.3.0.jar,
-XX:+CMSClassUnloadingEnabled, -XX:+UseThreadPriorities,
-XX:
While that sentence leaves a lot to be desired (for me because it confers a
different meaning on row store), it doesn't say "Cassandra is like a RDBMS"
- it says "like an RDBMS, it organises data by rows and columns" - i.e., in
this regard only it is like an RDBMS, not more generally.
I believe it
OK I got the response to one of my questions. In the script
/etc/init.d/cassandra we set the path for the heap dump by default in the
cassandra_home.
Now the thing I don't understand is, why do the dumps are located by the
file set by /etc/init.d/cassandra and not by the conf file
cassandra-env.s
Can someone please reply?
On Fri, Sep 30, 2016 at 11:25 PM, laxmikanth sadula wrote:
> Hi Eric,
>
> Thanks for the reply...
> RF=3 for all DCs...
>
> On Fri, Sep 30, 2016 at 9:57 PM, Eric Stevens wrote:
>
>> What is your replication factor in this DC?
>>
>> On Fri, Sep 30, 2016 at 8:08 AM techp
The phrase is defensible, but that is the root of the problem. Take for
example a skateboard.
"A skateboard is like a bike because it has wheels and you ride on it."
That is true and defensively true. :) However with not much more text you
can accurately describe what it is, as opposed to somethi
Also every piece of techincal information that describes a rowstore
http://cs-www.cs.yale.edu/homes/dna/talks/abadi-sigmod08-slides.pdf
https://en.wikipedia.org/wiki/Column-oriented_DBMS#Row-oriented_systems
Does it like this:
001:10,Smith,Joe,4;
002:12,Jones,Mary,5;
003:11,Johnson,Cathy
The equivalent statement would be: "Like a bike, a scooter has wheels."
This is a really important linguistic distinction you seem to be glossing
over. It is not saying "A is like X," it is saying "A has specific traits
in common with X."
For example "Like cancer, heart disease is a leading cau
Sorry Ed, but you're really stretching here. A table in Cassandra is
structured by a schema with the data for each row stored together in each
data file. Just because it uses log structured storage, sparse fields, and
semi-flexible collections doesn't disqualify it from calling it a "row
store"
Po
Whether a storage engine requires schema isn't really critical for row
oriented storage. How about CSV that doesn't have a header row? CSV is
probably the most commonly used row oriented storage and tons of businesses
still use it for B2B transactions.
As you pointed out, some traditional RDBMS ha
A couple things I would like to note:
1. Cassandra does not determine how data is stored on disk, the compaction
strategy does. One could, in theory, (and I believe some are trying) could
create a column-store compaction strategy. There is a large effort in the
database community overall to sepa
My original point can be summed up as:
Do not define cassandra in terms SMILES & METAPHORS. Such words include
"like" and "close relative".
For the specifics:
Any relational db could (and I'm sure one does!) allow for sparse fields as
well. MySQL can be backed by rocksdb now, does that make it n
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On Monday, October 3, 2016, Benedict Elliott Smith
wrote:
> While that sentence leaves a lot to be desired (for me because it confers
> a different meaning on row store), it doesn't say "Cassandra is like a
> RDBMS" - it says "like an RDBMS, it organises data by rows and columns" -
>
I was wondering: is (2) a direct consequence of a repair on the full
token range (and thus anti-compaction ran only on a subset of the RF
nodes)?. If I understand correctly, a repair with -pr should fix this,
at the cost of all nodes performing the anticompaction phase?
Cheers,
Stefano
On Tue, Se
It sounds like you're trying to avoid the latency of waiting for a write
confirmation to a remote data center?
App ==> DC1 ==high-latency==> DC2
If you need the write to be confirmed before you consider the write
successful in your application (definitely recommended unless you're ok
with losing
Thanks for the explanation Eric.
I would think it as something like:
The keyspace will be on dc1 + dc2, with the option that no long-term-data
is in dc1. So you write to dc1 (to the right nodes), they write to
commit-log/memtable and when they push for inter-dc-replication dc1 then
deletes local d
Hello All,
I am getting the below error repeatedly in the system log of C* 2.1.0
WARN [SharedPool-Worker-64] 2016-09-27 00:43:35,835 SliceQueryFilter.java:236
- Read 0 live and 1923 tombstoned cells in test_schema.test_cf.test_cf_col1_idx
(see tombstone_warn_threshold). 5000 columns was reques
Nobody is claiming Cassandra is a relational I'm not sure why that keeps
coming up.
On Mon, Oct 3, 2016 at 10:53 AM Edward Capriolo
wrote:
> My original point can be summed up as:
>
> Do not define cassandra in terms SMILES & METAPHORS. Such words include
> "like" and "close relative".
>
> For th
It's a row store because its schemed (vs ad hoc documents), and data (rows)
are stored together. What would you call the things you iterate over when
you query a partition? Rows. That makes it a thing that stores "rows" of
data, row store isn't some crazy stretch.
On Mon, Oct 3, 2016 at 12:33 PM Jo
... and my response can be summed up as "you are not parsing English
correctly." The word "like" does not mean what you think it means in this
context. It does not mean "close relative." It is constrained to the
similarities expressed, and no others. You don't seem to be reading any of
my respo
I've met clients that read the cassandra docs and then said in a big
meeting "it's just like relational database, it has tables just like
sqlserver/oracle."
I'm not putting words in other people's mouth either, but I've heard that
said enough times to want to puke. Does the docs claim cassandra is
"X-store" refers to how data is stored, in almost every case it refers to
what logical constructs are grouped together physically on disk. It has
nothing to do with whether a database is relational or not.
Cassandra does, in fact meet the definition of row-store, however, I would
like to re-itera
Nobody is disputing that the docs can and should be improved to avoid this
misreading. I've invited Ed to file a JIRA and/or pull request twice now.
You are of course just as welcome to do this. Perhaps you will actually do
it, so we can all move on with our lives!
On 3 October 2016 at 17:45
Hello All,
I am getting the below error repeatedly in the system log of C* 2.1.0
WARN [SharedPool-Worker-64] 2016-09-27 00:43:35,835 SliceQueryFilter.java:236
- Read 0 live and 1923 tombstoned cells in test_schema.test_cf.test_cf_col1_idx
(see tombstone_warn_threshold). 5000 columns was requ
@INDRANIL
Please go find your own thread and don't hijack mine.
On Mon, Oct 3, 2016 at 6:19 PM, INDRANIL BASU wrote:
> Hello All,
>
> I am getting the below error repeatedly in the system log of C* 2.1.0
>
> WARN [SharedPool-Worker-64] 2016-09-27 00:43:35,835
> SliceQueryFilter.java:236 - Read
Hi,
I was working on a utility which can be used for cassandra full table scan,
at a tremendously high velocity, cassandra fast full table scan.
How fast?
The script dumped ~ 229 million rows in 116 seconds, with a cluster of size
6 nodes.
Data transfer rates were upto 25MBps was observed on cassan
Hello Siddarth
I just throw an eye over the architecture diagram. The idea of using
multiple threads, one for each token range is great. It help maxing out
parallelism.
With https://issues.apache.org/jira/browse/CASSANDRA-11521 it would be even
faster.
On Mon, Oct 3, 2016 at 7:51 PM, siddharth v
Hi DuyHai,
Thanks for your reply.
A few more features planned in the next one(if there is one) like,
custom policy keeping in mind the replication of token range on specific
nodes,
fine graining the token range(for more speedup),
and a few more.
I think, as fine graining a token range,
If one toke
Hi, can anyone please help me with this
Thanks,
Abhinav
On Fri, Sep 30, 2016 at 6:20 PM Abhinav Solan
wrote:
> Hi Everyone,
>
> My table looks like this -
> CREATE TABLE test.reads (
> svc_pt_id bigint,
> meas_type_id bigint,
> flags bigint,
> read_time timestamp,
> value do
You know what don't "go low" and suggest the recent un-subscriber on me.
If your so eager to deal with my pull request please review this one:
I would rather you review this pull request:
https://issues.apache.org/jira/browse/CASSANDRA-10825
On Mon, Oct 3, 2016 at 1:04 PM, Benedict Elliott Sm
It will be interesting to have a comparison with spark here for basic use
cases.
>From a naive observation it appears that this could be slower than spark as
a lot of data is streamed over network.
On the other hand in this approach we have seen that Young GC takes nearly
full CPU (possibly becau
It almost sounds like you're duplicating all the work of both spark and the
connector. May I ask why you decided to not use the existing tools?
On Mon, Oct 3, 2016 at 2:21 PM siddharth verma
wrote:
> Hi DuyHai,
> Thanks for your reply.
> A few more features planned in the next one(if there is on
Hi Jon,
We couldn't setup a spark cluster.
For some use case, a spark cluster was required, but for some reason we
couldn't create spark cluster. Hence, one may use this utility to iterate
through the entire table at very high speed.
Had to find a work around, that would be faster than paging on r
Couldn't set up as couldn't get it working, or its not allowed?
On Mon, Oct 3, 2016 at 3:23 PM Siddharth Verma
wrote:
> Hi Jon,
> We couldn't setup a spark cluster.
>
> For some use case, a spark cluster was required, but for some reason we
> couldn't create spark cluster. Hence, one may use this
Hi Jon,
It wan't allowed.
Moreover, if someone who isn't familiar with spark, and might be new to map
filter reduce etc. operations, could also use the utility for some simple
operations assuming a sequential scan of the cassandra table.
Regards
Siddharth Verma
On Tue, Oct 4, 2016 at 1:32 AM, Jon
Hi Jonathan,
If full scan is a regular requirement then setting up a spark cluster in
locality with Cassandra nodes makes perfect sense. But supposing that it is
a one off requirement, say a weekly or a fortnightly task, a spark cluster
could be an added overhead with additional capacity, resource
I was thinking about this issue. I was wondering on the dev side if it
would make sense to make a utility for the unit tests that could enable
tracing and then assert that a number of steps in the trace happened.
Something like:
setup()
runQuery("SELECT * FROM X")
Assertion.assertTrace("Preparing
Which version of Cassandra are you running (I can tell it’s newer than 2.1, but
exact version would be useful)?
From: Abhinav Solan
Reply-To: "user@cassandra.apache.org"
Date: Monday, October 3, 2016 at 11:35 AM
To: "user@cassandra.apache.org"
Subject: Re: Row cache not working
Hi, ca
I undertook a similar effort a while ago.
https://issues.apache.org/jira/browse/CASSANDRA-7014
Other than the fact that it was closed with no comments, I can tell you
that other efforts I had to embed things in Cassandra did not go
swimmingly. Although at the time ideas were rejected like groovy
It's cassandra 3.0.7,
I had to set caching = {'keys': 'ALL', 'rows_per_partition': 'ALL'}, then
only it works don't know why.
If I set 'rows_per_partition':'1' then it does not work.
Also wanted to ask one thing, if I set row_cache_save_period: 60 then this
cache would be refreshed automatically o
Seems like it’s probably worth opening a jira issue to track it (either to
confirm it’s a bug, or to be able to better explain if/that it’s working as
intended – the row cache is probably missing because trace indicates the read
isn’t cacheable, but I suspect it should be cacheable).
Since the feature is off by default. The coverage might could be only as
deep as the specific tests that test it.
On Mon, Oct 3, 2016 at 4:54 PM, Jeff Jirsa
wrote:
> Seems like it’s probably worth opening a jira issue to track it (either to
> confirm it’s a bug, or to be able to better explain i
I did not ascribe blame. I only empathised with their predicament; I
don't want to listen to either of us, either!
On 3 October 2016 at 19:45, Edward Capriolo wrote:
> You know what don't "go low" and suggest the recent un-subscriber on me.
>
> If your so eager to deal with my pull request
If I remember correctly row cache caches only N rows from the beginning of the
partition. N being some configurable number.
See this link which is suggesting that:
http://www.datastax.com/dev/blog/row-caching-in-cassandra-2-1
Br,
Hannu
> On 4 Oct 2016, at 1.32, Edward Capriolo wrote:
>
> Sin
That’s true for versions 2.1 and newer. However, it’s possible that 3.0 engine
rewrite introduced a bug or two that haven’t yet been found.
From: Hannu Kröger
Reply-To: "user@cassandra.apache.org"
Date: Monday, October 3, 2016 at 3:52 PM
To: "user@cassandra.apache.org"
Subject: Re: Row
Dorian, I don't think Cassandra is able to achieve what you want natively.
In short words, what you want to achieve is conditional data replication.
Yabin
On Mon, Oct 3, 2016 at 1:37 PM, Dorian Hoxha wrote:
> @INDRANIL
> Please go find your own thread and don't hijack mine.
>
> On Mon, Oct 3,
Have you restarted Cassandra after making changes in cassandra-env.sh?
Yabin
On Mon, Oct 3, 2016 at 7:44 AM, Jean Carlo
wrote:
> OK I got the response to one of my questions. In the script
> /etc/init.d/cassandra we set the path for the heap dump by default in the
> cassandra_home.
>
> Now the
Most likely node A has some gossip related problems. You can try purging
the gossip state on node A, as per the procedure:
https://docs.datastax.com/en/cassandra/2.1/cassandra/operations/ops_gossip_purge.html
.
Yabin
On Mon, Oct 3, 2016 at 2:38 AM, Girish Kamarthi <
girish.kamar...@stellapps.com>
Are you sure cassandra.yaml file of the new node is correctly configured?
What is your seeds and listen_address setup of your new node and existing
nodes?
Yabin
On Fri, Sep 30, 2016 at 7:56 PM, Rajath Subramanyam
wrote:
> Hello Cassandra-users,
>
> I was running some tests today. My end goal wa
@Dorain, yes i did that by mistake. I rectified it by starting a new thread.
Thanks and regards,-- Indranil Basu
From: Dorian Hoxha
To: user@cassandra.apache.org; INDRANIL BASU
Sent: Monday, 3 October 2016 11:07 PM
Subject: Re: Way to write to dc1 but keep data only in dc2
@INDRA
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