> On Thursday, February 19, 2015, Thomas Steinmaurer <t...@iblogmanager.com > <mailto:t...@iblogmanager.com>> wrote: > > Jim, > > > > > http://www.cio.co.uk/insight/data-management/jim-starkeys-nosql-low-down-it-wont-solve-big-data-3598479/ > > What do you think about "tunable consistency" instead of "eventual > consistency"? > > > http://www.datastax.com/documentation/cassandra/2.0/cassandra/dml/dml_config_consistency_c.html > > > I stand by my statement that any adjective used to modify "consistency" > ie equivalent to "not." > > The Cassandra page seriously confuses the concepts of consistency and > durability. How can you have any form of consistency without > durability?
Are you using the durability term strictly in the area of transactions or in a sense that a successful write survives a system crash? If later, Cassandra has durable writes by first persisting a write operation into a commit log on disk before acknowledging a write operation as successful to the client. > It's completely legitimate to have settable durability > (NuoDB has more options than you can shake a stick at), but at the end > of the day, a transaction is either committed or it must appear that it > never existed. > > For me, consistency is dirt simple: A transaction sees a stable view of > the database but can't update a version of a record it could not see as > well as enforcement of any declared consistency constraints. A > corollary is that any and all reduced consistency modes are for the > birds and exist solely because record locking database systems cannot > perform without them. > > I invented MVCC to bring transactions to the masses; to make > transactions easier to use than not. All of the other crap are bandaids > on systems that essentially don't work. > > I learned at DEC that most options are the product of bad design where > the designer didn't have a right answer so gave the users a choice > between two bad answers. Bah! Why has NuoDB more durability options than you can shake a stick at it then? ;-) Na, seriously, thanks for your insights. Regards, Thomas ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=190641631&iu=/4140/ostg.clktrk Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
