I mean if I have secondary indexes. Apparently they are calculated in the background... On 9 December 2010 18:33, David Boxenhorn wrote: > What do you mean by indexing? > > On Thu, Dec 9, 2010 at 7:30 PM, Sébastien Druon wrote: > >> Thanks a lot for the answer >> >> What about the indexing when adding a new element? Is it incremental? >> >> Thanks again >> >> >> On 9 December 2010 14:38, David Boxenhorn wrote: >> >>> How about a regular CF where keys are N@N ? >>> >>> Then, getting a matrix row would be the same cost as getting a matrix >>> column (N gets), and it would be very easy to add element N+1. >>> >>> >>> On Thu, Dec 9, 2010 at 1:48 PM, Sébastien Druon wrote: >>> >>>> Hello, >>>> >>>> For a specific case, we are thinking about representing a N to N >>>> relationship with a NxN Matrix in Cassandra. >>>> The relations will be only between a subset of elements, so the Matrix >>>> will mostly contain empty elements. >>>> >>>> We have a set of questions concerning this: >>>> - what is the best way to represent this matrix? what would have the >>>> best performance in reading? in writing? >>>> . a super column family with n column families, with n columns each >>>> . a column family with n columns and n lines >>>> >>>> In the second case, we would need to extract 2 kinds of information: >>>> - all the relations for a line: this should be no specific problem; >>>> - all the relations for a column: in that case we would need an index >>>> for the columns, right? and then get all the lines where the value of the >>>> column in question is not null... is it the correct way to do? >>>> When using indexes, say we want to add another element N+1. What impact >>>> in terms of time would it have on the indexation job? >>>> >>>> Thanks a lot for the answers, >>>> >>>> Best regards, >>>> >>>> Sébastien Druon >>>> >>> >>> >> >