ok this makes sense thank u. -- francesco.tangari....@gmail.com Inviato con Sparrow (http://www.sparrowmailapp.com/?sig)
Il giorno giovedì 26 gennaio 2012, alle ore 21.36, aaron morton ha scritto: > Yes it is. > > But it depends on what you want to select. > > Cassandra does not have a complete query language like SQL in an RDBMS. You > need to design your data model to support the queries you wish to make. > Normally this means denormlising data so that queries are essentially reading > from a materialized view. > > So if you store users by user id, you can insert/update and select users by > user id. > > If you want so select all users who live in Spain then you need to have a > Secondary Index on the country column. Secondary indexes have overheads and > limitations just like indexes in a RDBMS. So if this is a common query may > want to denomalise the data so users are stored by user id and country. > > If one day you decide to select all users who are older than 30 but younger > than 40 you have to do some extra work. You could add another index on the > birthdate, but secondary indexes queries must have an equality clause so you > cannot do birthdate > x and birthday < y. This is where other query languages > such as HIVE or PIG and HADOOP come into play. > > Hope that helps. > > ----------------- > Aaron Morton > Freelance Developer > @aaronmorton > http://www.thelastpickle.com > > > > > > > On 26/01/2012, at 4:13 PM, francesco.tangari....@gmail.com > (mailto:francesco.tangari....@gmail.com) wrote: > > i don't get it. Suppose i have a data model and i have million of rows and > > suppose i want perform some select and some insert , it is not feasible to > > use cassandra for those reasons? > > > > -- > > francesco.tangari....@gmail.com (mailto:francesco.tangari....@gmail.com) > > Inviato con Sparrow (http://www.sparrowmailapp.com/?sig) > > > > > > Il giorno mercoledì 25 gennaio 2012, alle ore 09.13, aaron morton ha > > scritto: > > > > > You data load is fine. > > > > > > It sounds like you will run into issues with the data model and > > > functionality of cassandra. "Standard Analysis" in the RDBMS sense of > > > throwing any ad-hoc query at the data and letting the query engine work > > > it out is not possible without using HIVE/PIG or some other query > > > language. > > > > > > You will need to understand what sort of questions you want from the data > > > up from. The best way to learn this lesson is put together and quick > > > prototype and see how the data model works. > > > > > > Hope that helps. > > > > > > ----------------- > > > Aaron Morton > > > Freelance Developer > > > @aaronmorton > > > http://www.thelastpickle.com (http://www.thelastpickle.com/) > > > > > > > > > > > > > > > > > > > > > On 25/01/2012, at 8:09 PM, francesco.tangari....@gmail.com > > > (mailto:francesco.tangari....@gmail.com) wrote: > > > > make example of cases please? > > > > > > > > -- > > > > francesco.tangari....@gmail.com (mailto:francesco.tangari....@gmail.com) > > > > Inviato con Sparrow (http://www.sparrowmailapp.com/?sig) > > > > > > > > > > > > Il giorno mercoledì 25 gennaio 2012, alle ore 05.29, Gustavo Gustavo ha > > > > scritto: > > > > > > > > > That's for sure not much. > > > > > Your rdbms can probably hold the entire dataset in memory, and you > > > > > can do all kinds for queries that you want. Cassandra is for some > > > > > very specific use cases. > > > > > If you really need a cluster, have you thought about MySQL Cluster? > > > > > > > > > > 2012/1/25 <francesco.tangari....@gmail.com > > > > > (mailto:francesco.tangari....@gmail.com)> > > > > > > Standard analysis, display or aggregate some rows > > > > > > or standard operations that i can do on a normal dbms > > > > > > > > > > > > > > > > > > -- > > > > > > francesco.tangari....@gmail.com > > > > > > (mailto:francesco.tangari....@gmail.com) > > > > > > Inviato con Sparrow (http://www.sparrowmailapp.com/?sig) > > > > > > > > > > > > > > > > > > Il giorno mercoledì 25 gennaio 2012, alle ore 04.26, Maxim Potekhin > > > > > > ha scritto: > > > > > > > > > > > > > You provide zero information on what you are planning to do with > > > > > > > the data. > > > > > > > Thus, your question is impossible to answer. > > > > > > > > > > > > > > > > > > > > > On 1/24/2012 9:38 PM, francesco.tangari....@gmail.com > > > > > > > (mailto:francesco.tangari....@gmail.com) wrote: > > > > > > > > Do you think that for a standard project with 50.000.000 of > > > > > > > > rows on 2-3 machines cassandra is appropriate > > > > > > > > or i should use a normal dbms? > > > > > > > > > > > > > > > > -- > > > > > > > > francesco.tangari....@gmail.com > > > > > > > > (mailto:francesco.tangari....@gmail.com) > > > > > > > > Inviato con Sparrow (http://www.sparrowmailapp.com/?sig) > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
