NoSQL Movement?

Duncan Booth duncan.booth at invalid.invalid
Fri Mar 5 10:07:49 CET 2010


Gregory Ewing <greg.ewing at canterbury.ac.nz> wrote:

> Duncan Booth wrote:
>> Did I mention that bigtable doesn't require you to have the same 
>> columns in every record? The main use of bigtable (outside of 
Google's 
>> internal use) is Google App Engine and that apparently uses one 
table.
>> 
>> Not one table per application, one table total. It's a big table.
> 
> Seems to me in that situation the term "table" ceases to
> have any meaning. If every record can have its own unique
> structure, and data from completely unrelated applications
> can all be thrown in together, there's no more reason to
> call it a "table" than, say, "file", "database" or "big
> pile of data".
> 
I think it depends on how you look at things.

AppEngine uses a programming model which behaves very much as though you 
do have multiple tables: you use Django's programming model to wrap each 
record in a class, or you can use Gql query languages which looks very 
similar to SQL and again the class names appear in the place of table 
names.

So conceptually thinking of it as separate tables make a lot of sense, 
but the underlying implementation is apparently a single table where 
records simply have a type field that is used to instantiate the proper 
class on the Python side (and another hidden application field to 
prevent you accessing another application's data). Also of course 
records with the same type still may not all have the same columns if 
you change the class definition between runs, so even at this level they 
aren't tables in the strict SQL sense.

There may of course be other applications using bigtable where the 
bigtable(s) look much more like ordinary tables, but I don't know what 
they are.

>From your suggested terms, I'd agree you could call it a database rather 
than a table but I think it's too structured for "file" or "big pile of 
data" to be appropriate.

-- 
Duncan Booth http://kupuguy.blogspot.com



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