incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Michal August├Żn <augustyn.mic...@gmail.com>
Subject Re: Are row-keys sorted by the compareWith?
Date Fri, 18 Feb 2011 21:29:32 GMT
Hi,

I see "The CompareWith attribute tells Cassandra how to sort the columns for
slicing operations." on wiki (
http://wiki.apache.org/cassandra/StorageConfiguration). So the CompareWith
defines how to sort column (or super-columns) in scope of one row. So this
option is relate to (multi)get_slice operation.

I'm not sure if you can retrieve sorted rows. The only way how to get more
rows is "get_range_slices" method (and "get_indexed_slices") and there is no
sorting.

Augi

2011/2/18 cbertu81@libero.it <cbertu81@libero.it>

> Hi all,
> I created a CF in which i need to get, sorted by time, the Rows inside.
> Each
> Row represents a comment.
>
> <ColumnFamily name="Comments" compareWith="TimeUUIDType" / >
>
> I've created a few rows using as Row Key a generated TimeUUID but when I
> call
> the Pelops method "GetColumnsFromRows" I don't get the data back as I
> expect:
> rows are not sorted by TimeUUID.
> I though it was probably cause of the random-part of the TimeUUID so I
> create
> a new CF ...
>
> <ColumnFamily name="Comments2" compareWith="LongType" / >
>
> This time I created a few rows using the java System.CurrentTimeMillis()
> that
> retrieve a long. I call again the "GetColumnsFromRows" and again the same
> results: data are not sorted!
> I've read many times that Rows are sorted as specified in the compareWith
> but
> I can't see it.
> To solve this problem for the moment I've used a SuperColumnFamily with an
> UNIQUE ROW ... but I think this is just a workaround and not the solution.
>
> <ColumnFamily name="Comments" type="Super" compareWith="TimeUUIDType"
> CompareSubcolumnsWith="BytesType"/ >
>
> Now when I call the "GetSuperColumnsFromRow" I get all the SuperColumns as
> I
> expected: sorted by TimeUUID. Why it does not happen the same with the
> Rows?
> I'm confused.
>
> TIA for any help.
>
> Best Regards
>
> Carlo
>

Mime
View raw message