I'm having a difficult time understanding your syntax. Could you provide an example with actual data?
On May 10, 2010, at 5:25 PM, AJ Chen wrote: > your suggestion works for fixed supercolumn name. the blog example now > becomes: > { blog-id {name, title, ...} > blog-id-comments {time:commenter} > } > > what about supercolumn names that are not fixed? for example, I want to store > comment's details with the blog like this: > { blog-id { blog { name, title, ...} > comments {comment-id:commenter} > comment-id {commenter, time, text, ...} > } > > a comment-id is generated on-the-fly when the comment is made. how do you > flatten the comment-id supercolumn to normal column? just for brain > exercise, not meant to pick on you. > > thanks, > -aj > > > > On Mon, May 10, 2010 at 4:39 PM, William Ashley <wash...@gmail.com> wrote: > If you're storing your super column under a fixed name, you could just > concatenate that name with the row key and use normal columns. Then you get > your paging and sorting the way you want it. > > > On May 10, 2010, at 4:31 PM, AJ Chen wrote: > >> supercolumn is good for modeling profile type of data. simple example is >> blog: >> blog { blog {author, title, ...} >> comments {time: commenter} //sort by TimeUUID >> } >> when retrieving a blog, you get all the comments sorted by time already. >> without supercolumn, you would need to concatenate multiple comment times >> together as you suggested. >> >> requiring user to concatenating data fields together is not only an extra >> burden on user but also a less clean design. there will be cases where the >> list property of a profile data is a long list (say a million items). in >> such cases, user wants to be able to directly insert/delete an item in that >> list because it's more efficient. Retrieving the whole list, updating it, >> concatenating again, and then putting it back to datastore is awkward and >> less efficient. >> >> -aj >> >> >> On Mon, May 10, 2010 at 2:20 PM, Mike Malone <m...@simplegeo.com> wrote: >> On Mon, May 10, 2010 at 1:38 PM, AJ Chen <ajc...@web2express.org> wrote: >> Could someone confirm this discussion is not about abandoning supercolumn >> family? I have found modeling data with supercolumn family is actually an >> advantage of cassadra compared to relational database. Hope you are going to >> drop this important concept. How it's implemented internally is a different >> matter. >> >> SuperColumns are useful as a convenience mechanism. That's pretty much it. >> There's _nothing_ (as far as I can tell) that you can do with SuperColumns >> that you can't do by manually concatenating key names with a separator on >> the client side and implementing a custom comparator on the server (as ugly >> as that is). >> >> This discussion is about getting rid of SuperColumns and adding a more >> generic mechanism that will actually be useful and interesting and will >> continue to be convenient for the types of use cases for which people use >> SuperColumns. >> >> If there's a particular use case that you feel you can only implement with >> SuperColumns, please share! I honestly can't think of any. >> >> Mike >> >> >> On Mon, May 10, 2010 at 10:08 AM, Jonathan Shook <jsh...@gmail.com> wrote: >> Agreed >> >> On Mon, May 10, 2010 at 12:01 PM, Mike Malone <m...@simplegeo.com> wrote: >> > On Mon, May 10, 2010 at 9:52 AM, Jonathan Shook <jsh...@gmail.com> wrote: >> >> >> >> I have to disagree about the naming of things. The name of something >> >> isn't just a literal identifier. It affects the way people think about >> >> it. For new users, the whole naming thing has been a persistent >> >> barrier. >> > >> > I'm saying we shouldn't be worried too much about coming up with names and >> > analogies until we've decided what it is we're naming. >> > >> >> >> >> As for your suggestions, I'm all for simplifying or generalizing the >> >> "how it works" part down to a more generalized set of operations. I'm >> >> not sure it's a good idea to require users to think in terms building >> >> up a fluffy query structure just to thread it through a needle of an >> >> API, even for the simplest of queries. At some point, the level of >> >> generic boilerplate takes away from the semantic hand rails that >> >> developers like. So I guess I'm suggesting that "how it works" and >> >> "how we use it" are not always exactly the same. At least they should >> >> both hinge on a common conceptual model, which is where the naming >> >> becomes an important anchoring point. >> > >> > If things are done properly, client libraries could expose simplified query >> > interfaces without much effort. Most ORMs these days work by building a >> > propositional directed acyclic graph that's serialized to SQL. This would >> > work the same way, but it wouldn't be converted into a 4GL. >> > Mike >> > >> >> >> >> Jonathan >> >> >> >> On Mon, May 10, 2010 at 11:37 AM, Mike Malone <m...@simplegeo.com> wrote: >> >> > Maybe... but honestly, it doesn't affect the architecture or interface >> >> > at >> >> > all. I'm more interested in thinking about how the system should work >> >> > than >> >> > what things are called. Naming things are important, but that can happen >> >> > later. >> >> > Does anyone have any thoughts or comments on the architecture I >> >> > suggested >> >> > earlier? >> >> > >> >> > Mike >> >> > >> >> > On Mon, May 10, 2010 at 8:36 AM, Schubert Zhang <zson...@gmail.com> >> >> > wrote: >> >> >> >> >> >> Yes, the "column" here is not appropriate. >> >> >> Maybe we need not to create new terms, in Google's Bigtable, the term >> >> >> "qualifier" is a good one. >> >> >> >> >> >> On Thu, May 6, 2010 at 3:04 PM, David Boxenhorn <da...@lookin2.com> >> >> >> wrote: >> >> >>> >> >> >>> That would be a good time to get rid of the confusing "column" term, >> >> >>> which incorrectly suggests a two-dimensional tabular structure. >> >> >>> >> >> >>> Suggestions: >> >> >>> >> >> >>> 1. A hypercube (or hypocube, if only two dimensions): replace "key" >> >> >>> and >> >> >>> "column" with "1st dimension", "2nd dimension", etc. >> >> >>> >> >> >>> 2. A file system: replace "key" and "column" with "directory" and >> >> >>> "subdirectory" >> >> >>> >> >> >>> 3. A tuple tree: "Column family" replaced by top-level tuple, whose >> >> >>> value >> >> >>> is the set of keys, whose value is the set of supercolumns of the key, >> >> >>> whose >> >> >>> value is the set of columns for the supercolumn, etc. >> >> >>> >> >> >>> 4. Etc. >> >> >>> >> >> >>> On Thu, May 6, 2010 at 2:28 AM, Mike Malone <m...@simplegeo.com> >> >> >>> wrote: >> >> >>>> >> >> >>>> Nice, Ed, we're doing something very similar but less generic. >> >> >>>> Now replace all of the various methods for querying with a simple >> >> >>>> query >> >> >>>> interface that takes a Predicate, allow the user to specify (in >> >> >>>> storage-conf) which levels of the nested Columns should be indexed, >> >> >>>> and >> >> >>>> completely remove Comparators and have people subclass Column / >> >> >>>> implement >> >> >>>> IColumn and we'd really be on to something ;). >> >> >>>> Mock storage-conf.xml: >> >> >>>> <Column Name="ThingThatsNowKey" Indexed="True" >> >> >>>> ClusterPartitioned="True" Type="UTF8"> >> >> >>>> <Column Name="ThingThatsNowColumnFamily" DiskPartitioned="True" >> >> >>>> Type="UTF8"> >> >> >>>> <Column Name="ThingThatsNowSuperColumnName" Type="Long"> >> >> >>>> <Column Name="ThingThatsNowColumnName" Indexed="True" >> >> >>>> Type="ASCII"> >> >> >>>> <Column Name="ThingThatCantCurrentlyBeRepresented"/> >> >> >>>> </Column> >> >> >>>> </Column> >> >> >>>> </Column> >> >> >>>> </Column> >> >> >>>> Thrift: >> >> >>>> struct NamePredicate { >> >> >>>> 1: required list<binary> column_names, >> >> >>>> } >> >> >>>> struct SlicePredicate { >> >> >>>> 1: required binary start, >> >> >>>> 2: required binary end, >> >> >>>> } >> >> >>>> struct CountPredicate { >> >> >>>> 1: required struct predicate, >> >> >>>> 2: required i32 count=100, >> >> >>>> } >> >> >>>> struct AndPredicate { >> >> >>>> 1: required Predicate left, >> >> >>>> 2: required Predicate right, >> >> >>>> } >> >> >>>> struct SubColumnsPredicate { >> >> >>>> 1: required Predicate columns, >> >> >>>> 2: required Predicate subcolumns, >> >> >>>> } >> >> >>>> ... OrPredicate, OtherUsefulPredicates ... >> >> >>>> query(predicate, count, consistency_level) # Count here would be >> >> >>>> total >> >> >>>> count of leaf values returned, whereas CountPredicate specifies a >> >> >>>> column >> >> >>>> count for a particular sub-slice. >> >> >>>> Not fully baked... but I think this could really simplify stuff and >> >> >>>> make >> >> >>>> it more flexible. Downside is it may give people enough rope to hang >> >> >>>> themselves, but at least the predicate stuff is easily distributable. >> >> >>>> I'm thinking I'll play around with implementing some of this stuff >> >> >>>> myself if I have any free time in the near future. >> >> >>>> Mike >> >> >>>> >> >> >>>> On Wed, May 5, 2010 at 2:04 PM, Jonathan Ellis <jbel...@gmail.com> >> >> >>>> wrote: >> >> >>>>> >> >> >>>>> Very interesting, thanks! >> >> >>>>> >> >> >>>>> On Wed, May 5, 2010 at 1:31 PM, Ed Anuff <e...@anuff.com> wrote: >> >> >>>>> > Follow-up from last weeks discussion, I've been playing around >> >> >>>>> > with a >> >> >>>>> > simple >> >> >>>>> > column comparator for composite column names that I put up on >> >> >>>>> > github. I'd >> >> >>>>> > be interested to hear what people think of this approach. >> >> >>>>> > >> >> >>>>> > http://github.com/edanuff/CassandraCompositeType >> >> >>>>> > >> >> >>>>> > Ed >> >> >>>>> > >> >> >>>>> > On Wed, Apr 28, 2010 at 12:52 PM, Ed Anuff <e...@anuff.com> wrote: >> >> >>>>> >> >> >> >>>>> >> It might make sense to create a CompositeType subclass of >> >> >>>>> >> AbstractType for >> >> >>>>> >> the purpose of constructing and comparing these types of >> >> >>>>> >> "composite" >> >> >>>>> >> column >> >> >>>>> >> names so that if you could more easily do that sort of thing >> >> >>>>> >> rather >> >> >>>>> >> than >> >> >>>>> >> having to concatenate into one big string. >> >> >>>>> >> >> >> >>>>> >> On Wed, Apr 28, 2010 at 10:25 AM, Mike Malone >> >> >>>>> >> <m...@simplegeo.com> >> >> >>>>> >> wrote: >> >> >>>>> >>> >> >> >>>>> >>> The only thing SuperColumns appear to buy you (as someone >> >> >>>>> >>> pointed >> >> >>>>> >>> out to >> >> >>>>> >>> me at the Cassandra meetup - I think it was Eric Florenzano) is >> >> >>>>> >>> that you can >> >> >>>>> >>> use different comparator types for the Super/SubColumns, I >> >> >>>>> >>> guess..? >> >> >>>>> >>> But you >> >> >>>>> >>> should be able to do the same thing by creating your own Column >> >> >>>>> >>> comparator. >> >> >>>>> >>> I guess my point is that SuperColumns are mostly a convenience >> >> >>>>> >>> mechanism, as >> >> >>>>> >>> far as I can tell. >> >> >>>>> >>> Mike >> >> >>>>> > >> >> >>>>> > >> >> >>>>> >> >> >>>>> >> >> >>>>> >> >> >>>>> -- >> >> >>>>> Jonathan Ellis >> >> >>>>> Project Chair, Apache Cassandra >> >> >>>>> co-founder of Riptano, the source for professional Cassandra support >> >> >>>>> http://riptano.com >> >> >>>> >> >> >>> >> >> >> >> >> > >> >> > >> > >> > >> >> >> >> -- >> AJ Chen, PhD >> Chair, Semantic Web SIG, sdforum.org >> http://web2express.org >> twitter @web2express >> Palo Alto, CA, USA >> >> >> >> >> -- >> AJ Chen, PhD >> Chair, Semantic Web SIG, sdforum.org >> http://web2express.org >> twitter @web2express >> Palo Alto, CA, USA > > > > > -- > AJ Chen, PhD > Chair, Semantic Web SIG, sdforum.org > http://web2express.org > twitter @web2express > Palo Alto, CA, USA