"range query" vs "slice range query"
hi guys, i'm reading up on the book "Cassandra - Definitive guide" and i don't seem to understand what it says about "ranges and slices" my understanding is a range as in "a mathematical range to define a subset from an ordered set of elements", in cassandra typically means a range of rows whereas a slice means a range of columns. a range query refers to a query to retrieve a range of rows whereas a slice range queyr refers to a query to retrieve range of columns within a row. i may be talking about total nonsense but i really am more confused after reading this portion of the book http://books.google.com/books?id=MKGSbCbEdg0C&pg=PA134&lpg=PA134&dq=cassandra+%22range+query%22+%22range+slice%22&source=bl&ots=XoPB4uA60u&sig=uDDoQe0FRkQobHnr-vPvvQ3B8TQ&hl=en&ei=ub3cTcvGLZLevQOuxs3CDw&sa=X&oi=book_result&ct=result&resnum=4&ved=0CCwQ6AEwAw#v=onepage&q=cassandra%20%22range%20query%22%20%22range%20slice%22&f=false many thanx in advance david
Re: "range query" vs "slice range query"
so, that was actually simpler than i thought ay? cheers guys~ On 26 May 2011 05:38, Roland Gude wrote: > That is correct. Random partitioner orders rows according to the MD5 sum. > > Am 25.05.2011 um 16:11 schrieb "Robert Jackson" >: > > Also, it is my understanding that if you are not using > OrderPreservingPartitioner a get_range_slices may not return what you would > expect. > > With the RandomPartitioner you can iterate over the complete list by using > the last row key as the start for subsequent requests, but if you are using > a single query you will be returned all the rows where the returned row > key's md5 is between the md5 of the start row key and stop row key. > > Reference: > http://wiki.apache.org/cassandra/FAQ - "Why aren't range slices/sequential > scans giving me the expected results?" > > Robert Jackson > > -- > *From: *"Jonathan Ellis" > *To: *user@cassandra.apache.org > *Sent: *Wednesday, May 25, 2011 8:54:34 AM > *Subject: *Re: "range query" vs "slice range query" > > get_range_slices is the api to get a slice (of columns) from each of a > range (of rows) > > On Wed, May 25, 2011 at 3:42 AM, david lee wrote: > > hi guys, > > i'm reading up on the book "Cassandra - Definitive guide" > > and i don't seem to understand what it says about "ranges and slices" > > my understanding is > > a range as in "a mathematical range to define a subset from an ordered > set > > of elements", > > in cassandra typically means a range of rows whereas > > a slice means a range of columns. > > a range query refers to a query to retrieve a range of rows whereas > > a slice range queyr refers to a query to retrieve range of columns within > a > > row. > > i may be talking about total nonsense but i really am more confused after > > reading this portion of the book > > > http://books.google.com/books?id=MKGSbCbEdg0C&pg=PA134&lpg=PA134&dq=cassandra+%22range+query%22+%22range+slice%22&source=bl&ots=XoPB4uA60u&sig=uDDoQe0FRkQobHnr-vPvvQ3B8TQ&hl=en&ei=ub3cTcvGLZLevQOuxs3CDw&sa=X&oi=book_result&ct=result&resnum=4&ved=0CCwQ6AEwAw#v=onepage&q=cassandra%20%22range%20query%22%20%22range%20slice%22&f=false > > many thanx in advance > > david > > > > > > -- > Jonathan Ellis > Project Chair, Apache Cassandra > co-founder of DataStax, the source for professional Cassandra support > http://www.datastax.com > >
minimum number of machines for RF=3
hi guys, is there a minimum(recommended) number of machines for RF=3? i encountered a test result where # of nodes = 3 RF = 3 CL.READ=QUORUM and when 1 node was taken out and back in after which node repair was run, the TPS dropped significantly. is this behaviour expected since the RF (for the duration of when 1 node was taken out) is higher than the # of nodes? cheers, david
Re: minimum number of machines for RF=3
cheers~ On 7 July 2011 19:41, Watanabe Maki wrote: > It is expected behaviour and not relate on number of node. > After the failed node bringing back, the ring will be busy by Hinted > Handoff rewriting and Read Repair. If you run repair, all your 3 nodes need > to build Merkel Tree, compare the hash values, then transfer latest data to > each other. > > You can tune the HH, read repair to reduce performance impact on self > healing activities. > > maki > > On 2011/07/07, at 18:10, david lee wrote: > > > hi guys, > > > > is there a minimum(recommended) number of machines for RF=3? > > > > i encountered a test result where > > # of nodes = 3 > > RF = 3 > > CL.READ=QUORUM > > and when 1 node was taken out and back in after which node repair was > run, > > the TPS dropped significantly. > > > > is this behaviour expected since the RF (for the duration of when 1 node > was taken out) > > is higher than the # of nodes? > > > > cheers, > > david > >
log4j settings inquiry
hi,
i'm trying to run cassandra 0.7 on my windows machine,
and i don't seem to be able to go beyond the warning message
C:\Program Files\Apache Software
Foundation\apache-cassandra-0.7.4\bin>cassandra
-f
Starting Cassandra Server
log4j:WARN No appenders could be found for logger
(org.apache.cassandra.service.
AbstractCassandraDaemon).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for
more in
fo.
in my conf folder, i have log4j-server.properties which looks like
log4j.rootLogger=INFO,stdout,R
# stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p %d{HH:mm:ss,SSS} %m%n
# rolling log file
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.maxFileSize=20MB
log4j.appender.R.maxBackupIndex=50
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%5p [%t] %d{ISO8601} %F (line %L)
%m%n
# Edit the next line to point to your logs directory
log4j.appender.R.File=file:C:/var/log/cassandra/system.log
any help will be much appreciated.
thanx in advnace
Re: log4j settings inquiry
specifying the path using the file:// protocol worked like a charm.
thank you very much Aaron for your help.
but i was wondering why
-Dlog4j.configuration=log4j-server.properties didn't work and
-Dlog4j.configuration=file://"C:\Program Files\Apache Software
Foundation\apache-cassandra-0.7.4\conf\log4j-server.properties"^ worked so i
tried to place cassandra's home folder to a folder without any space
characters
and it worked without using file:// protocol as well.
i guess it's the issue with log4j not being able to handle space characters
well.
On 25 March 2011 05:14, aaron morton wrote:
> Just checking the obvious thing, are you running cassandra or cassandra.bat
> ? (cannot imagine you would even get as far as you did but I like asking
> questions).
>
> It's all a bit strange because the code in 0.7.4 will throw some errors if
> it cannot resolve a path to load the config from.
>
> You can hard code the log config path by modifying the line
> -Dlog4j.configuration=log4j-server.properties^
>
> in cassandra.bat and specifying a path using the file:// protocol
>
> Hope that helps.
> Aaron
>
> On 24 Mar 2011, at 19:40, david lee wrote:
>
> hi,
> i'm trying to run cassandra 0.7 on my windows machine,
> and i don't seem to be able to go beyond the warning message
>
> C:\Program Files\Apache Software
> Foundation\apache-cassandra-0.7.4\bin>cassandra
> -f
> Starting Cassandra Server
> log4j:WARN No appenders could be found for logger
> (org.apache.cassandra.service.
> AbstractCassandraDaemon).
> log4j:WARN Please initialize the log4j system properly.
> log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for
> more in
> fo.
>
> in my conf folder, i have log4j-server.properties which looks like
> log4j.rootLogger=INFO,stdout,R
>
> # stdout
> log4j.appender.stdout=org.apache.log4j.ConsoleAppender
> log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
> log4j.appender.stdout.layout.ConversionPattern=%5p %d{HH:mm:ss,SSS} %m%n
>
> # rolling log file
> log4j.appender.R=org.apache.log4j.RollingFileAppender
> log4j.appender.R.maxFileSize=20MB
> log4j.appender.R.maxBackupIndex=50
> log4j.appender.R.layout=org.apache.log4j.PatternLayout
> log4j.appender.R.layout.ConversionPattern=%5p [%t] %d{ISO8601} %F (line %L)
> %m%n
> # Edit the next line to point to your logs directory
> log4j.appender.R.File=file:C:/var/log/cassandra/system.log
>
> any help will be much appreciated.
>
> thanx in advnace
>
>
>
