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/>* >>>> >>> >>> >> >
