How to quickly install and start experimenting with Cassandra. Part 2

This is a continuation of the article "How to quickly install and start experimenting with Cassandra" , published in Habré

What you can not do in Cassandra, but would like to:

• Indexing, and search by ... generally for some reason. Indexing will have to do manually. Partly can help project Lucandra - Lucene for Cassandra
• You can not quickly (for O (1)) find out the total number of records
• Don't even think about transactions
• You can forget about map reduce, at least in the upcoming versions.
• There are no delimitations of tables by users (this is not in the current stable version 0.51, in the future it will be)
• There are difficulties in adding new bases, for this you have to stop Cassandra (they promise to fix it in the upcoming versions)
• Only simple requests, for example, to get the 10 most popular blogs, will have to work
• In irc, I was extremely advised not to store pictures in Cassandra

Rails

For Rails, there is a cassandra_object analogue to active_record. It is interesting in that it builds the index itself for some fields, but you will have to manually edit the configuration file. I talked to the developers, there are plans to do this automatically.

Tests

There is still such advice, if you are thinking of using Cassandra, test absolutely everything, even the simplest queries.
After each test will have to clean up the database, it can be done like this:

 class ActiveSupport :: TestCase
   def teardown
     CassandraObject :: Base.connection.clear_keyspace!
   end
 end

By the way, this command does not guarantee complete cleaning of all records, but it is usually suitable for tests.
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More well-known gem'om (cassandra, cassandra_object) no. Maybe my work will be useful to you:

• attribute_normalizer for Cassandra is fork of attribute_normalizer for active_record. Tests are still in the process of writing, but fork works
• Cassandra session store (not yet published)
• Simple authorization system. This is a converted clearence plugin (not yet published)