Also every piece of techincal information that describes a rowstore http://cs-www.cs.yale.edu/homes/dna/talks/abadi-sigmod08-slides.pdf https://en.wikipedia.org/wiki/Column-oriented_DBMS#Row-oriented_systems
Does it like this: 001:10,Smith,Joe,40000; 002:12,Jones,Mary,50000; 003:11,Johnson,Cathy,44000; 004:22,Jones,Bob,55000; The never depict a scenario where a the data looks like this on disk: 001:10,Smith 001:10,40000; Which is much closer to how Cassandra *stores* it's data. On Fri, Sep 30, 2016 at 5:12 PM, Benedict Elliott Smith <bened...@apache.org > wrote: > Absolutely. A "partitioned row store" is exactly what I would call it. > As it happens, our README thinks the same, which is fantastic. > > I thought I'd take a look at the rest of our cohort, and didn't get far > before disappointment. HBase literally calls itself a "*column-oriented* > store" > - which is so totally wrong it's simultaneously hilarious and tragic. > > I guess we can't blame the wider internet for misunderstanding/misnaming > us poor "wide column stores" if even one of the major examples doesn't know > what it, itself, is! > > > > > On 30 September 2016 at 21:47, Jonathan Haddad <j...@jonhaddad.com> wrote: > >> +1000 to what Benedict says. I usually call it a "partitioned row store" >> which usually needs some extra explanation but is more accurate than >> "column family" or whatever other thrift era terminology people still use. >> On Fri, Sep 30, 2016 at 1:53 PM DuyHai Doan <doanduy...@gmail.com> wrote: >> >>> I used to present Cassandra as a NoSQL datastore with "distributed" >>> table. This definition is closer to CQL and has some academic background >>> (distributed hash table). >>> >>> >>> On Fri, Sep 30, 2016 at 7:43 PM, Benedict Elliott Smith < >>> bened...@apache.org> wrote: >>> >>>> Cassandra is not a "wide column store" anymore. It has a schema. Only >>>> thrift users no longer think they have a schema (though they do), and >>>> thrift is being deprecated. >>>> >>>> I really wish everyone would kill the term "wide column store" with >>>> fire. It seems to have never meant anything beyond "schema-less, >>>> row-oriented", and a "column store" means literally the opposite of this. >>>> >>>> Not only that, but people don't even seem to realise the term "column >>>> store" existed long before "wide column store" and the latter is often >>>> abbreviated to the former, as here: http://www.planetcassandra.org >>>> /what-is-nosql/ >>>> >>>> Since it no longer applies, let's all agree as a community to forget >>>> this awful nomenclature ever existed. >>>> >>>> >>>> >>>> On 30 September 2016 at 18:09, Joaquin Casares < >>>> joaq...@thelastpickle.com> wrote: >>>> >>>>> Hi Mehdi, >>>>> >>>>> I can help clarify a few things. >>>>> >>>>> As Carlos said, Cassandra is a Wide Column Store. Theoretically a row >>>>> can have 2 billion columns, but in practice it shouldn't have more than >>>>> 100 >>>>> million columns. >>>>> >>>>> Cassandra partitions data to certain nodes based on the partition >>>>> key(s), but does provide the option of setting zero or more clustering >>>>> keys. Together, the partition key(s) and clustering key(s) form the >>>>> primary >>>>> key. >>>>> >>>>> When writing to Cassandra, you will need to provide the full primary >>>>> key, however, when reading from Cassandra, you only need to provide the >>>>> full partition key. >>>>> >>>>> When you only provide the partition key for a read operation, you're >>>>> able to return all columns that exist on that partition with low latency. >>>>> These columns are displayed as "CQL rows" to make it easier to reason >>>>> about. >>>>> >>>>> Consider the schema: >>>>> >>>>> CREATE TABLE foo ( >>>>> bar uuid, >>>>> >>>>> boz uuid, >>>>> >>>>> baz timeuuid, >>>>> data1 text, >>>>> >>>>> data2 text, >>>>> >>>>> PRIMARY KEY ((bar, boz), baz) >>>>> >>>>> ); >>>>> >>>>> >>>>> When you write to Cassandra you will need to send bar, boz, and baz >>>>> and optionally data*, if it's relevant for that CQL row. If you chose not >>>>> to define a data* field for a particular CQL row, then nothing is stored >>>>> nor allocated on disk. But I wouldn't consider that caveat to be >>>>> "schema-less". >>>>> >>>>> However, all writes to the same bar/boz will end up on the same >>>>> Cassandra replica set (a configurable number of nodes) and be stored on >>>>> the >>>>> same place(s) on disk within the SSTable(s). And on disk, each field >>>>> that's >>>>> not a partition key is stored as a column, including clustering keys (this >>>>> is optimized in Cassandra 3+, but now we're getting deep into internals). >>>>> >>>>> In this way you can get fast responses for all activity for bar/boz >>>>> either over time, or for a specific time, with roughly the same number of >>>>> disk seeks, with varying lengths on the disk scans. >>>>> >>>>> Hope that helps! >>>>> >>>>> Joaquin Casares >>>>> Consultant >>>>> Austin, TX >>>>> >>>>> Apache Cassandra Consulting >>>>> http://www.thelastpickle.com >>>>> >>>>> On Fri, Sep 30, 2016 at 11:40 AM, Carlos Alonso <i...@mrcalonso.com> >>>>> wrote: >>>>> >>>>>> Cassandra is a Wide Column Store http://db-engines.com/en >>>>>> /system/Cassandra >>>>>> >>>>>> Carlos Alonso | Software Engineer | @calonso >>>>>> <https://twitter.com/calonso> >>>>>> >>>>>> On 30 September 2016 at 18:24, Mehdi Bada < >>>>>> mehdi.b...@dbi-services.com> wrote: >>>>>> >>>>>>> Hi all, >>>>>>> >>>>>>> I have a theoritical question: >>>>>>> - Is Apache Cassandra really a column store? >>>>>>> Column store mean storing the data as column rather than as a rows. >>>>>>> >>>>>>> In fact C* store the data as row, and data is partionned with row >>>>>>> key. >>>>>>> >>>>>>> Finally, for me, Cassandra is a row oriented schema less DBMS.... Is >>>>>>> it true for you also??? >>>>>>> >>>>>>> Many thanks in advance for your reply >>>>>>> >>>>>>> Best Regards >>>>>>> Mehdi Bada >>>>>>> ---- >>>>>>> >>>>>>> *Mehdi Bada* | Consultant >>>>>>> Phone: +41 32 422 96 00 | Mobile: +41 79 928 75 48 | Fax: +41 32 >>>>>>> 422 96 15 >>>>>>> dbi services, Rue de la Jeunesse 2, CH-2800 Delémont >>>>>>> mehdi.b...@dbi-services.com >>>>>>> www.dbi-services.com >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> *⇒ dbi services is recruiting Oracle & SQL Server experts ! – Join >>>>>>> the team >>>>>>> <http://www.dbi-services.com/fr/dbi-services-et-ses-collaborateurs/offres-emplois-opportunites-carrieres/>* >>>>>>> >>>>>> >>>>>> >>>>> >>>> >>> >
