Thanks, that's great! Truly an awesome project. Is there a way to specify a composite row key composed of the fields specified in the table schema much like a definition of a primary key in oracle table? For example a rowkey can look like: (CustomerID)(StartTimeMs)(RequestId)
Sent from my iPhone On 15 בנוב 2012, at 20:26, Aaron Kimball <akimbal...@gmail.com> wrote: > Hi Asaf, > > This is a good point. Our user guide is vague on the subject, but under the > hood, we are actually storing in each cell an integer id that is assigned > to the writer schema. KijiSchema maintains the id-to-schema mappings in a > metadata table (also stored in HBase) and looks them up as needed. I have > logged https://jira.kiji.org/browse/DOCS-2 to note this improvement > > Cheers, > - Aaron > > > On Wed, Nov 14, 2012 at 9:58 PM, Asaf Mesika <asaf.mes...@gmail.com> wrote: > >> Hi, >> This looks great! >> >> I have a question regarding schema. It is written in the user guide that >> the schema of a cell is saved next to the data in the cell. I presume it >> would: >> Takes more spaces, as schema is duplicated for each row this cell is saved >> at >> Makes reading records slower since it needs to parse the Avro Schema >> before reading each cell >> >> Did I manage to understand the guide correctly? >> >> Thanks! >> >> Asaf >> >> >> On 15 בנוב 2012, at 00:18, Aaron Kimball <akimbal...@gmail.com> wrote: >> >>> HBase fans, >>> >>> I’m writing to announce the first release of KijiSchema, a new project to >>> help developers build applications on HBase. You can download it at >>> www.kiji.org. It is open source and published under the Apache 2 >> license. >>> >>> KijiSchema simplifies the development of applications on HBase by >> providing >>> developer-friendly Java APIs for storing and managing typed data using >> Avro. >>> >>> As an application grows, developers can gracefully evolve the application >>> schema at the cell level to handle new fields. These features are >>> particularly well suited for entity-centric data schemas where all >>> information about a given entity, including dimensional and transaction >>> data, is encoded within the same row. >>> >>> Column names and associations of columns with schemas are maintained in a >>> data dictionary; developers don’t need to rely on reading source code to >>> remember where data is stored. >>> >>> Table schemas can be defined in JSON or by using KijiSchema’s declarative >>> DDL. Developers can also easily run MapReduce over Kiji tables in HBase >>> using included MR Input- and OutputFormats. >>> >>> KijiSchema is an open and highly modular system. It runs on top of an >>> existing HBase 0.92 (CDH4) cluster, and can be run entirely on the client >>> with no server-side daemons. KijiSchema can also be downloaded as part >> of a >>> Kiji BentoBox, which provides a clean install of a mini-cluster of >> Hadoop, >>> HBase and Kiji on your laptop in under 15 min. You do not need to have >>> Hadoop or HBase pre-installed to run the BentoBox. >>> >>> KijiSchema is inspired by work we have done at WibiData developing >>> applications for recommendations and personalization on top of HBase. We >>> will be developing and releasing other components into the Kiji project >> to >>> provide additional functionality enabling easy development of data >>> applications on HBase, including improvements for MapReduce support and >>> querying tools. We welcome feedback and contributions from the community >> to >>> the Kiji Project at www.kiji.org. >>> >>> Regards, >>> - Aaron Kimball >> >>
