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Posted to user@cassandra.apache.org by "David G. Boney" <db...@semanticartifacts.com> on 2010/12/28 06:01:17 UTC

Supercolumn Maximums

1. What are the maximum number of supercolumns that a row can have?
2. Are supercolumns indexed?
3. What are the maximum number of subcolumns in a supercolumn?
-------------
Sincerely,
David G. Boney
dboney1@semanticartifacts.com
http://www.semanticartifacts.com

Re: Which Java on Fedora? Sun's or GNU's?

Posted by Eric Evans <ee...@rackspace.com>.
On Thu, 2010-12-30 at 14:34 +0800, Zhu Han wrote:
> Do you use the default GC settings?  Can you show me the openJDK version by
> "java -version"? Thank you!

Yes, the default GC settings.  OpenJDK is b11, from Debian Lenny.

http://packages.debian.org/lenny/openjdk-6-jre-headless

> If everything is the same, I suspect I need to upgrade the kernel.

We're also running Lenny's default kernel, 2.6.26.

-- 
Eric Evans
eevans@rackspace.com

Re: Which Java on Fedora? Sun's or GNU's?

Posted by Zhu Han <sc...@gmail.com>.
Eric,

Do you use the default GC settings?  Can you show me the openJDK version by
"java -version"? Thank you!

If everything is the same, I suspect I need to upgrade the kernel.

best regards,
hanzhu


On Wed, Dec 29, 2010 at 11:44 PM, Eric Evans <ee...@rackspace.com> wrote:

> On Wed, 2010-12-29 at 11:11 +0100, Peter Schuller wrote:
> > > Which is best?
> > > Which is preferred?
> >
> > If by "GNU" you mean the gcj stuff, then absolutely no. :)
> >
> > If you mean OpenJDK it's less obvious but I believe the general
> > recommendation is to go with the Sun JVM.
>
> FWIW, I'm using OpenJDK with Cassandra (always have) and haven't had any
> problems.
>
> --
> Eric Evans
> eevans@rackspace.com
>
>

Re: Which Java on Fedora? Sun's or GNU's?

Posted by Eric Evans <ee...@rackspace.com>.
On Wed, 2010-12-29 at 11:11 +0100, Peter Schuller wrote:
> > Which is best?
> > Which is preferred?
> 
> If by "GNU" you mean the gcj stuff, then absolutely no. :)
> 
> If you mean OpenJDK it's less obvious but I believe the general
> recommendation is to go with the Sun JVM.

FWIW, I'm using OpenJDK with Cassandra (always have) and haven't had any
problems.

-- 
Eric Evans
eevans@rackspace.com

Re: Which Java on Fedora? Sun's or GNU's?

Posted by Zhu Han <sc...@gmail.com>.
I met with native memory leak with OpenJDK. Still try to figure it out...

best regards,
hanzhu


On Wed, Dec 29, 2010 at 6:11 PM, Peter Schuller <peter.schuller@infidyne.com
> wrote:

> > Which is best?
> > Which is preferred?
>
> If by "GNU" you mean the gcj stuff, then absolutely no. :)
>
> If you mean OpenJDK it's less obvious but I believe the general
> recommendation is to go with the Sun JVM.
>
> --
> / Peter Schuller
>

Re: Which Java on Fedora? Sun's or GNU's?

Posted by Peter Schuller <pe...@infidyne.com>.
> Which is best?
> Which is preferred?

If by "GNU" you mean the gcj stuff, then absolutely no. :)

If you mean OpenJDK it's less obvious but I believe the general
recommendation is to go with the Sun JVM.

-- 
/ Peter Schuller

Re: Which Java on Fedora? Sun's or GNU's?

Posted by "Andrey V. Panov" <pa...@gmail.com>.
At the moment I'm use Sun JDK. But I think in some future I should migrate
to openJDK because it's more safety!? JRocket will be merged with HotSpot
and I think they already did it.

On 29 December 2010 14:21, AJ <aj...@dude.podzone.net> wrote:

> I did install by hand with the previous release.  I suppose the RPM's are
> just a convenience, eh?  But, if the only real dependency is Java, then
> there isn't much need for an RPM right now?
>
> But, what do you think about other JREs?  Sun, JRocket, or Gnu?
>
> Thanks,
> aj
>
>
> On 12/28/2010 11:11 PM, Andrey V. Panov wrote:
>
>> Why not install Cassandra by hands? You should only download it and
>> unpack... Only thing left is boot script.
>>
>
>

Re: Which Java on Fedora? Sun's or GNU's?

Posted by AJ <aj...@dude.podzone.net>.
I did install by hand with the previous release.  I suppose the RPM's 
are just a convenience, eh?  But, if the only real dependency is Java, 
then there isn't much need for an RPM right now?

But, what do you think about other JREs?  Sun, JRocket, or Gnu?

Thanks,
aj

On 12/28/2010 11:11 PM, Andrey V. Panov wrote:
> Why not install Cassandra by hands? You should only download it and 
> unpack... Only thing left is boot script.

Re: Which Java on Fedora? Sun's or GNU's?

Posted by "Andrey V. Panov" <pa...@gmail.com>.
Why not install Cassandra by hands? You should only download it and
unpack... Only thing left is boot script.

Re: Which Java on Fedora? Sun's or GNU's?

Posted by Edward Capriolo <ed...@gmail.com>.
On Wed, Dec 29, 2010 at 11:29 AM, Eric Evans <ee...@rackspace.com> wrote:
> On Wed, 2010-12-29 at 10:56 -0500, Edward Capriolo wrote:
>> Cassandra pushes your JVM hard. Do not count on your distro which
>> might provide versions of things that are 3 months to 2 years old.
>
> Come on.  If it worked fine 3 months ago, then chances are it will
> continue to.  This is one of the reasons that people choose
> (environmentally )stable distro releases (which are often supported for
> much longer than 2 years).
>
>> Chosing what your distro gives your prepare to be disappointed and
>> have to upgrade as soon as you get some respectable load.  If you are
>> using sun/oracle (That still feels strange to say JVM oracle) you want
>> something much higher then just 1.6.0. Go for the latest and greatest
>> 1.6.21 or higher JRE/JDK 1.6.23.
>
> FWIW, the wiki says: "For Sun's jvm, this means at least u19; u21 is
> better."
>
>> I install the JDK (not the JRE) because its a super set and hey I just
>> might feel like compiling something.
>>
>> Other not so great options... rpm -Uvh --force --skip-deps (If you
>> know you have a Java that your RPM manager does not know about)
>
> No.  If this is really the situation, then it's disingenuous to offer
> the package at all, and it should be dropped.   I don't think these
> command line arguments should ever appear on a public mailing list.
>
>> Get source RPM strip out the Java dependency (If you know you have a
>> Java that your RPM manager does not know about)
>> Create a source RPM with nothing in it that "PROVIDES JAVA" (If you
>> know you have a Java that your RPM manager does not know about)
>
> --
> Eric Evans
> eevans@rackspace.com
>
>
If it worked fine three months ago and you came into Cassandra IRC
with a random JVM problem the first thing someone would tell you to do
is probably update to the latest JVM :)

Some distro's go for perceived stability over bug/performance
enhancements in there package choices. For example (a major unnamed
linux distribution) still ships mysql 5.0 rather then 5.1, or
BerkelyDB that NEVER gets upgraded. Why? Tracking these packages and
all the downstream changes from code that links to mysql or BDB would
result in way to much churn, that would make them look less stable and
"enterprise like".

Another major distribution allows anyone to submit a package, as a
result they end up with hundreds/thousands of packages that NEVER get
updated or supported in any meaningful way.

As for Cassandra there are two key components Java and Cassandra. If
you are just taking whatever the distro gives you for these things,
you should probably do more research.

As to not letting the cat out of the bag on what you can do with RPM.
I agree, half heartedly. RPM is a glorified tar, and when it begins
insisting you need 40 dependent libraries you do not really need
(which is very common especially in the RPM Java world) because some
applet in the buried in an example somewhere just might need
x11....Well I am more likely to edit the source RPM and make myself
happy then let RPM install all of gnome just so the RPM is happy.

In this case OpenJDK or SUN should meet the java >=1.6.0 requirement.

Edward

Re: Which Java on Fedora? Sun's or GNU's?

Posted by Eric Evans <ee...@rackspace.com>.
On Wed, 2010-12-29 at 10:56 -0500, Edward Capriolo wrote:
> Cassandra pushes your JVM hard. Do not count on your distro which
> might provide versions of things that are 3 months to 2 years old.

Come on.  If it worked fine 3 months ago, then chances are it will
continue to.  This is one of the reasons that people choose
(environmentally )stable distro releases (which are often supported for
much longer than 2 years).

> Chosing what your distro gives your prepare to be disappointed and
> have to upgrade as soon as you get some respectable load.  If you are
> using sun/oracle (That still feels strange to say JVM oracle) you want
> something much higher then just 1.6.0. Go for the latest and greatest
> 1.6.21 or higher JRE/JDK 1.6.23.

FWIW, the wiki says: "For Sun's jvm, this means at least u19; u21 is
better."

> I install the JDK (not the JRE) because its a super set and hey I just
> might feel like compiling something.
> 
> Other not so great options... rpm -Uvh --force --skip-deps (If you
> know you have a Java that your RPM manager does not know about)

No.  If this is really the situation, then it's disingenuous to offer
the package at all, and it should be dropped.   I don't think these
command line arguments should ever appear on a public mailing list.

> Get source RPM strip out the Java dependency (If you know you have a
> Java that your RPM manager does not know about)
> Create a source RPM with nothing in it that "PROVIDES JAVA" (If you
> know you have a Java that your RPM manager does not know about) 

-- 
Eric Evans
eevans@rackspace.com

Re: Which Java on Fedora? Sun's or GNU's?

Posted by Edward Capriolo <ed...@gmail.com>.
On Wed, Dec 29, 2010 at 10:47 AM, Eric Evans <ee...@rackspace.com> wrote:
> On Tue, 2010-12-28 at 19:32 -0700, AJ wrote:
>> Which is best?
>> Which is preferred?
>
> The RPM depends on "java >= 1.6.0", so you need something that provides
> that.  Maybe someone who uses Redhat can chime in with what exactly?
> Does Fedora have OpenJDK packages?
>
> --
> Eric Evans
> eevans@rackspace.com
>
>

Cassandra pushes your JVM hard. Do not count on your distro which
might provide versions of things that are 3 months to 2 years old.
Chosing what your distro gives your prepare to be disappointed and
have to upgrade as soon as you get some respectable load.  If you are
using sun/oracle (That still feels strange to say JVM oracle) you want
something much higher then just 1.6.0. Go for the latest and greatest
1.6.21 or higher JRE/JDK 1.6.23.

I install the JDK (not the JRE) because its a super set and hey I just
might feel like compiling something.

Other not so great options... rpm -Uvh --force --skip-deps (If you
know you have a Java that your RPM manager does not know about)
Get source RPM strip out the Java dependency (If you know you have a
Java that your RPM manager does not know about)
Create a source RPM with nothing in it that "PROVIDES JAVA" (If you
know you have a Java that your RPM manager does not know about)

I prefer the Sun JDK which meets the requirements ( and hey I love
that compressed Oopse option!)

Re: Which Java on Fedora? Sun's or GNU's?

Posted by Eric Evans <ee...@rackspace.com>.
On Tue, 2010-12-28 at 19:32 -0700, AJ wrote:
> Which is best?
> Which is preferred?

The RPM depends on "java >= 1.6.0", so you need something that provides
that.  Maybe someone who uses Redhat can chime in with what exactly?
Does Fedora have OpenJDK packages?

-- 
Eric Evans
eevans@rackspace.com

Which Java on Fedora? Sun's or GNU's?

Posted by AJ <aj...@dude.podzone.net>.
Hi,

Which is best?
Which is preferred?

If Sun's JRE is better, then how do I get it installed so that the 
Cassandra rpm/yum installer recognizes it?

I was trying to install the Cassandra 0.7.0-rc3 rpm release and it 
doesn't recognize the installed jre from Sun, so the install fails.  
This was on Oracle's RHEL.  But, I think I'm going to ditch Oracle and 
go with Fedora since Cassandra seems to support it, right?

Thanks,
aj

Re: Supercolumn Maximums

Posted by "David G. Boney" <db...@semanticartifacts.com>.
I am confused. In NEWS.txt in the source code, it says for Cassandra 7.0,"Row size limit increased from 2GB to 2 billion columns". Does this mean that the maximum number of supercolumns is also 2 billion?

I am not asking about secondary indexes. I am asking if the keys for the supercolumns are indexed in a row.

-------------
Sincerely,
David G. Boney
dboney1@semanticartifacts.com
http://www.semanticartifacts.com




On Dec 27, 2010, at 11:33 PM, Narendra Sharma wrote:

> #1 - No limit
> #2 - If you are referring to secondary indexes then NO. Also see https://issues.apache.org/jira/browse/CASSANDRA-598
> #3 - No limit
> 
> Following are key limitations:
> 1. All data for a single row must fit (on disk) on a single machine in the cluster
> 2. A single column value may not be larger than 2GB. 
> 
> See more on:
> http://wiki.apache.org/cassandra/CassandraLimitations
> 
> 
> -Naren
> 
> On Mon, Dec 27, 2010 at 9:01 PM, David G. Boney <db...@semanticartifacts.com> wrote:
> 1. What are the maximum number of supercolumns that a row can have?
> 2. Are supercolumns indexed?
> 3. What are the maximum number of subcolumns in a supercolumn?
> -------------
> Sincerely,
> David G. Boney
> dboney1@semanticartifacts.com
> http://www.semanticartifacts.com
> 
> 
> 
> 
>

Re: Supercolumn Maximums

Posted by Narendra Sharma <na...@gmail.com>.
#1 - No limit
#2 - If you are referring to secondary indexes then NO. Also see
https://issues.apache.org/jira/browse/CASSANDRA-598
#3 - No limit

Following are key limitations:
1. All data for a single row must fit (on disk) on a single machine in the
cluster
2. A single column value may not be larger than 2GB.

See more on:
http://wiki.apache.org/cassandra/CassandraLimitations


-Naren

On Mon, Dec 27, 2010 at 9:01 PM, David G. Boney <
dboney1@semanticartifacts.com> wrote:

> 1. What are the maximum number of supercolumns that a row can have?
> 2. Are supercolumns indexed?
> 3. What are the maximum number of subcolumns in a supercolumn?
> -------------
> Sincerely,
> David G. Boney
> dboney1@semanticartifacts.com
> http://www.semanticartifacts.com
>
>
>
>
>