cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Stephen Pope <Stephen.P...@quest.com>
Subject RE: Replacing supercolumns with composite columns; Getting the equivalent of retrieving a list of supercolumns by name
Date Wed, 04 Jan 2012 13:33:36 GMT
I don't think I can tell my exact column names in many cases. For example most of our queries
are for specific keys, and an unknown range of numbers (like key1, key where number > 10000).
How can I set up my slice in this case to retrieve only the columns that match both criteria?

Cheers,
Steve

From: rajkumar.w93@gmail.com [mailto:rajkumar.w93@gmail.com] On Behalf Of Asil Klin
Sent: Wednesday, January 04, 2012 12:21 AM
To: user@cassandra.apache.org
Subject: Re: Replacing supercolumns with composite columns; Getting the equivalent of retrieving
a list of supercolumns by name

@Stephan: in that case, you can easily tell the names of all columns you want to retrieve,
so you can make a query to retrieve those list of composite columns.


@Jeremiah,
So where is my best bet ? Should I leave the supercolumns as it is as of now, since I can
find a good way to use them incase I replace them with composite columns?


On Wed, Jan 4, 2012 at 4:01 AM, Stephen Pope <Stephen.Pope@quest.com<mailto:Stephen.Pope@quest.com>>
wrote:
 The bonus you're talking about here, how do I apply that?

 For example, my columns are in the form of number.id<http://number.id> such as 4.steve,
4.greg, 5.steve, 5.george. Is there a way to query a slice of numbers with a list of ids?
As in, I want all the columns with numbers between 4 and 10 which have ids steve or greg.

 Cheers,
 Steve

-----Original Message-----
From: Jeremiah Jordan [mailto:jeremiah.jordan@morningstar.com<mailto:jeremiah.jordan@morningstar.com>]
Sent: Tuesday, January 03, 2012 3:12 PM
To: user@cassandra.apache.org<mailto:user@cassandra.apache.org>
Cc: Asil Klin
Subject: Re: Replacing supercolumns with composite columns; Getting the equivalent of retrieving
a list of supercolumns by name

The main issue with replacing super columns with composite columns right now is that if you
don't know all your sub-column names you can't select multiple "super columns" worth of data
in the same query without getting extra stuff.  You have to use a slice to get all subcolumns
of a given super column, and you can't have disjoint slices, so if you want two super columns
full, you have to get all the other stuff that is in between them, or make two queries.
If you know what all of the sub-column names are you can ask for all of the super/sub column
pairs for all of the super columns you want and not get extra data.

If you don't need to pull multiple super columns at a time with slices like that, then there
isn't really an issue.

A bonus of using composite keys like this, is that if there is a specific sub column you want
from multiple super columns, you can pull all those out with a single multiget and you don't
have to pull the rest of the columns...

So there are pros and cons...

-Jeremiah


On 01/03/2012 01:58 PM, Asil Klin wrote:
> I have a super columns family which I always use to retrieve a list of
> supercolumns(with all subcolumns) by name. I am looking forward to
> replace all SuperColumns in my schema with the composite columns.
>
> How could I design schema so that I could do the equivalent of
> retrieving a list of supercolumns by name, in case of using composite
> columns.
>
> (As of now I thought of using the supercolumn name as the first
> component of the composite name and the subcolumn name as 2nd
> component of composite name.)


Mime
View raw message