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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: Dynamic CF
Date Tue, 10 Jul 2012 14:37:19 GMT
On Tue, Jul 10, 2012 at 4:17 PM, Leonid Ilyevsky
<lilyevsky@mooncapital.com> wrote:
> So I guess, in the batch_mutate call, in the map that I pass to it, only the first element
of the composite key should be used as a key (because it is the real key), and the other parts
of the key should be passed as regular columns? Is this correct? While I am waiting for your
confirmation, I am going to try it.

I would really advise you to use the BATCH statement of CQL3 rather
than the thrift batch_mutate call. If only because until
https://issues.apache.org/jira/browse/CASSANDRA-4377 is resolved it
won't work at all, but also because the whole point of CQL3 is to hide
that kind of complexity.

--
Sylvain

>
> -----Original Message-----
> From: Sylvain Lebresne [mailto:sylvain@datastax.com]
> Sent: Tuesday, July 10, 2012 8:24 AM
> To: user@cassandra.apache.org
> Subject: Re: Dynamic CF
>
> On Fri, Jul 6, 2012 at 10:49 PM, Leonid Ilyevsky
> <lilyevsky@mooncapital.com> wrote:
>> At this point I am really confused about what direction Cassandra is going. CQL 3
has the benefit of composite keys, but no dynamic columns.
>> I thought, the whole point of Cassandra was to provide dynamic tables.
>
> CQL3 absolutely provide "dynamic tables"/wide rows, the syntax is just
> different. The typical example for wide rows is a time serie, for
> instance keeping all the events for a given event_kind in the same C*
> row ordered by time. You declare that in CQL3 using:
>   CREATE TABLE events (
>     event_kind text,
>     time timestamp,
>     event_name text,
>     event_details text,
>     PRIMARY KEY (event_kind, time)
>   )
>
> The important part in such definition is that one CQL row (i.e a given
> event_kind, time, event_name, even_details) does not map to an internal
> Cassandra row. More precisely, all events sharing the same event_kind will be
> in the same internal row. This is a wide row/dynamic table in the sense of
> thrift.
>
>
>> I need to have a huge table to store market quotes, and be able to query it by name
and timestamp (t1 <= t <= t2), therefore I wanted the composite key.
>> Loading data to such table using prepared statements (CQL 3-based) was very slow,
because it makes a server call for each row.
>
> You should use a BATCH statement which is the equivalent to batch_mutate.
>
> --
> Sylvain
>
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