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The "ThomasBoose/EERD model components to Cassandra Column family's" page has been changed by ThomasBoose. http://wiki.apache.org/cassandra/ThomasBoose/EERD%20model%20components%20to%20Cassandra%20Column%20family%27s?action=diff&rev1=11&rev2=12 -------------------------------------------------- If this is not yet making sence, read on. - - === Indexing === In order to add an index to a column, other then the ColumnFamily key, we should to create a second ColumnFamily. Every insert, which can be either an insert or update in Cassandra, on the original ColumnFamily we will update the corresponding index. @@ -29, +27 @@ This way a hash will be created containing columns for every person's key that lives in a specific City. The ColumnFamily architecture of Cassandra can store a unlimited number of columns for each key. This meens that when deleting a person it's reference in the cfi_Person_City index should be removed first. When updating a person, maybe moving to anothor City, we have to remove the element from the cfi_Person_City first and then store it with the corresponding new City.'' '' === Deleting values === - Because of the way Cassandra clusters operate it is nearly impossible to delete values and know for sure the values are deleted on everynode. If values would simply be deleted and afterwards a node turns up which still holds the given value it would replicate ths value back to the existing nodes. Read more about deleting values at: DistributedDeletes + Because of the way Cassandra clusters operate it is nearly impossible to delete values and know for sure the values are deleted on every node. If values would simply be deleted and afterwards a node turns up which still holds the given value it would replicate ths value back to the existing nodes. Read more about deleting values at: DistributedDeletes Cassandra on the other hand is isanely fast at inserting and updating values. This is why I would advise any programmer trying to build DBMS logic to introduce a value that "meens " deleted and have you DBMS tier respond "Does not exist" in both cases, when values actualy do not exist or contain the "deleted" value. Cassandra makes no distinction between updates and inserts so updating from "deleted" and inserting can be achieved the same way.
