Hi Aaron, Thank you for your reply, i appreciate the suggestions you made.
Yesterday i managed to get everything (our main read) in one CF, with the use of a structure in a value like you suggested. Designing a new data model is different from what i'm used to, but if you keep in mind that you designing for performance instead of flexibility then everything gets a bit easier. Kind regards, T. Akhayo 2011/3/30 aaron morton <aa...@thelastpickle.com> > I would go with the solution that means you only have to make one request > to serve your reads, so consider the super CF approach. > > There are some downsides to super columns see > http://wiki.apache.org/cassandra/CassandraLimitations and they tend to > have a love-them-hate-them reputation. > > One thing to consider is that you do not need to model every attribute of > your entity as a column in cassandra. Especially if you are always going to > pull back all the attributes. So you could do your super CF approach with a > standard CF, just pack the columns into some sort of structure such as JSON > and store them as a blob. > > Or you can use a naming scheme in the column names with a standard CF, e.g. > uuid1.text and uuid2.text > > Hope that helps. > Aaron > > On 30 Mar 2011, at 01:05, T Akhayo wrote: > > Good afternoon, > > I'm making my data model from scratch for cassandra, this means i can tune > and fine tune it for performance. > > At this time i'm having problems choosing between a 2 column families or 1 > super column family. I will illustrate with a example. > > Sector, this defines a place, this is one or two properties. > Entry, a entry that is bound to a sector, this is simply some text and a > few properties. > > I can model this with a super column family: > > sectors{ //super column family > sector1{ > uid1{ > text: a text > user: joop > } > uid2{ > text: more text > user: piet > } > } > sector2{ > uid10{ > text: even more text > user: marie > } > } > } > > But i can also model this with 2 column families: > > sectors{ // column family > sector1{ > textid1: null > textid2: null > } > sector2{ > textid4: null > } > } > > texts{ //column family > textid1{ > text: a text > user: joop > } > textid2{ > text: more text > user: piet > } > } > > With the super column family i can retrieve a list of texts for a specific > sector with only 1 request to cassandra. > > With the 2 column families i need to send 2 requests to cassandra: > 1. give me all textids from sector x. (returns x, y, z) > 2. give me all texts that have id x, y, z. > > In my final application it is likely that there will be a bit more writes > compared to reads. > > I was wondering what the best approach is when it comes to performance. I > suspect that using super column families is slower compared the using column > families, but is it stil slower when using 2 column families and with 2 > request to cassandra instead of 1 (with super column family). > > Kind regards, > T. Akhayo > > >
