 |
 |
SQL-style JOINs can be done in CouchDB (can't speak for the other NoSQL DB's). In CouchDB, it's called view collation: http://chrischandler.name/couchdb/view-collation-for-join-like-behavior-in-couchdb/ It's a different way of thinking (as there are no tables, and map/reduce goes through every document to generate it's output), but it is possible to get interestingly combined data out of the whole database. Later, Benjamin -- President BigBlueHat P: 864.232.9553 W: http://www.bigbluehat.com/ http://www.linkedin.com/in/benjaminyoung On 4/12/10 11:08 AM, Robert Sanderson wrote: > Depends on the sort of features required, in particular the access > patterns, and the hardware it's going to run on. > > In my experience, NoSQL systems (for example apache's Cassandra) have > extremely good distribution properties over multiple machines, much > better than SQL databases. Essentially, it's easier to store a bunch > of key/values in a distributed fashion, as you don't need to do joins > across tables (there aren't any) and eventually consistent systems > (such as Cassandra) don't even need to always be internally consistent > between nodes. > > If many concurrent write accesses are required, then NoSQL can also be > a good choice, for the same reasons as it's easily distributed. > And for the same reasons, it can be much faster than SQL systems with > the same data given a data model that fits the access patterns. > > The flip side is that if later you want to do something that just > requires the equivalent of table joins, it has to be done at the > application level. This is going to be MUCH MUCH slower and harder > than if there was SQL underneath. > > > Rob > > > On Mon, Apr 12, 2010 at 7:55 AM, Thomas Dowling<[log in to unmask]> wrote: > >> So let's say (hypothetically, of course) that a colleague tells you he's >> considering a NoSQL database like MongoDB or CouchDB, to store a couple >> tens of millions of "documents", where a document is pretty much an >> article citation, abstract, and the location of full text (not the full >> text itself). Would your reaction be: >> >> "That's a sensible, forward-looking approach. Lots of sites are putting >> lots of data into these databases and they'll only get better." >> >> "This guy's on the bleeding edge. Personally, I'd hold off, but it could >> work." >> >> "Schedule that 2012 re-migration to Oracle or Postgres now." >> >> "Bwahahahah!!!" >> >> Or something else? >> >> >> >> (<http://en.wikipedia.org/wiki/NoSQL> is a good jumping-in point.) >> >> >> -- >> Thomas Dowling >> [log in to unmask] >> >>