Joshua Tolley wrote:
> http://en.wikipedia.org/wiki/Column_oriented_database
> This has come up on the lists from time to time; the short answer is it's
> really hard.
>
indeed. among other issues is, just what order should those columns be
stored in? database tables have no implicit order, they are abstractly
unordered sets of rows. an index can impose an order but a given table
can have multiple indexes, and a given query can sort on most any
arbitrary thing it wants. and, say you are storing the columns sorted
by the primary key, how do you do inserts or updates that change this
order?
instead of one table with (key, v1, v2, v3) how about N tables, (k,v1),
(k,v2), (k,v3) ? or at least, one extra table with just the value
that you want columnar access to?