Interesting idea, Jim. Is there a reason you don't you use "metadata:{accountId}" instead? For performance reasons?
On Sat, Feb 4, 2012 at 6:24 PM, Jim Ancona <j...@anconafamily.com> wrote: > I've used "special" values which still comply with the Composite > schema for the metadata columns, e.g. a column of > 1970-01-01:{accountId} for a metadata column where the Composite is > DateType:UTF8Type. > > Jim > > On Sat, Feb 4, 2012 at 2:13 PM, Yiming Sun <yiming....@gmail.com> wrote: > > Thanks Andrey and Chris. It sounds like we don't necessarily have to use > > composite columns. From what I understand about dynamic CF, each row may > > have completely different data from other rows; but in our case, the > data > > in each row is similar to other rows; my concern was more about the > > homogeneity of the data between columns. > > > > In our original supercolumn-based schema, one special supercolumn is > called > > "metadata" which contains a number of subcolumns to hold metadata > describing > > each collection (e.g. number of documents, etc.), then the rest of the > > supercolumns in the same row are all IDs of documents belong to the > > collection, and for each document supercolumn, the subcolumns contain the > > document content as well as metadata on individual document (e.g. > checksum > > of each document). > > > > To move away from the supercolumn schema, I could either create two CFs, > one > > to hold metadata, the other document content; or I could create just one > CF > > mixing metadata and doc content in the same row, and using composite > column > > names to identify if the particular column is metadata or a document. I > am > > just wondering if you have any inputs on the pros and cons of each > schema. > > > > -- Y. > > > > > > On Fri, Feb 3, 2012 at 10:27 PM, Chris Gerken < > chrisger...@mindspring.com> > > wrote: > >> > >> > >> > >> > >> On 4 February 2012 06:21, Yiming Sun <yiming....@gmail.com> wrote: > >>> > >>> I cannot have one composite column name with 3 components while another > >>> with 4 components? > >> > >> Just put 4 components and left last empty (if it is same type)?! > >> > >>> Another question I have is how flexible composite columns actually are. > >>> If my data model has a CF containing US zip codes with the following > >>> composite columns: > >>> > >>> {OH:Spring Field} : 45503 > >>> {OH:Columbus} : 43085 > >>> {FL:Spring Field} : 32401 > >>> {FL:Key West} : 33040 > >>> > >>> I know I can ask cassandra to "give me the zip codes of all cities in > >>> OH". But can I ask it to "give me the zip codes of all cities named > Spring > >>> Field" using this model? Thanks. > >> > >> No. You set first composite component at first. > >> > >> > >> I'd use a dynamic CF: > >> row key = state abbreviation > >> column name = city name > >> column value = zip code (or a complex object, one of whose properties is > >> zip code) > >> > >> you can iterate over the columns in a single row to get a state's city > >> names and their zip code and you can do a get_range_slices on all keys > for > >> the columns starting and ending on the city name to find out the zip > codes > >> for a cities with the given name. > >> > >> I think > >> > >> - Chris > > > > >