Sonia, If you haven't visited the site below, I think it does the best job of explaining what Cassandra is all about:
http://arin.me/blog/wtf-is-a-supercolumn-cassandra-data-model Consider a group of ColumFamilies within a Keyspace like a group of tables in a database. CompareWith tells Cassandra how to sort the data and it is sorted by the types you described. So if you tell it to sort by UTF8Type it will consider the in the column that matches your row key to be UTF8 data and will sort accordingly. From: sonia gehlot <sonia.geh...@gmail.com> To: user@cassandra.apache.org Subject: Cassandra basics Date: Fri, 23 Jul 2010 15:48:12 -0700 Hi Guys, Recently I have started reading about Cassandra from the material available on net. But I have very confused with the basic understanding of Cassandra. I understand columnFamilies, supper columnFamilies but I have no clear understanding of <Keyspace Name="Twitter"> <ColumnFamily CompareWith="UTF8Type" Name="Statuses" /> <ColumnFamily CompareWith="UTF8Type" Name="StatusAudits" /> <ColumnFamily CompareWith="UTF8Type" Name="StatusRelationships" CompareSubcolumnsWith="TimeUUIDType" ColumnType="Super" /> <ColumnFamily CompareWith="UTF8Type" Name="Users" /> <ColumnFamily CompareWith="UTF8Type" Name="UserRelationships" CompareSubcolumnsWith="TimeUUIDType" ColumnType="Super" /> </Keyspace> <ColumnFamily Name = "LocationUserIndexSCF" CompareWith = "UTF8Types" CompareSubcolumnsWith= "UTF8Type" ColumnType = "Super"/> 1. I don't understand what is this "CompareWith", "CompareSuperColumnWith", "CompareSubcolumnsWith" etc is? 2. What is "UTF8Type", "TimeUUIDType", "LongType", "ASCIIType" etc.. is these are datatypes? as we have datatype in SQL, if so then is this is datatype of value stored in this column family? May be I am getting confused because I am mixing my Relational databases fundamentals with distributed. Please If someone can explain me significance of these things then it would be very helpful. Thanks in advance. Please reply. Sonia ____________________________________________________________ FIRE SALE: iPads for $23.74? SPECIAL REPORT: iPads are being auctioned for an incredible 85% off! http://thirdpartyoffers.juno.com/TGL3131/4c4a393b224513eab65st05duc
