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From "Vegard Berget" <p...@fantasista.no>
Subject Re: how to handle join properly in this case
Date Mon, 27 May 2013 06:56:53 GMT
Hi,
I am no expert, but a couple of suggestions:1)  Remember that writes
are very fast i Cassandra, so don't be afraid to store more
information than you would in an Sql-ish server. 2)  It would be
better with an example, but again - by storing more than you would in
an sql-schema, would you still need to compute a table C?  Is it
possible to have just the CF A, and have all data in that CF?  Would
it be possible/easier to have the rules applied on the client, so that
you don't have to change the schema/recalculate CF C?  
.vegard,

----- Original Message -----
From: user@cassandra.apache.org
To:
Cc:
Sent:Sat, 25 May 2013 15:22:00 -0700
Subject:how to handle join properly in this case

 Hi Experts,

 We have tables (a.k.a. column family) A and B. The row of the table
is
 simply a key value pair. Table A and B are written by clients all the
 time. We need to transform the row key of table A and B according to
 a set of rules, join these two tables and save the results to table C
 for read.

 Questions
 1) Schema like this is very close to a schema in SQL. We mainly want
 to separate read and write operations by different column families.
Is
 this a correct way to model the join in Cassandra?

 2) If the rules change a little bit, which is quite possible, we will
 have to drop table C, and recompute the join result, which seems to
be
 cumbersome because not all the join results need to be changed, just
 some of them. Are there any better ways to handle such change?

 Thanks a lot.

 --
 Regards,
 Jiaan


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