It's true there is overlap. But the original article as well as that dbms2 link focus on "query" performance. Mapreduce is specifically not designed for live queries, or really anything where the output is less than 10G or so. So its performance is no good for those things. On the other hand, at least as far as I am aware, with a data warehouse you can do some batch processing but SQL UDFs are fundamentally restricted. It is implausible to communicate with remote servers or parse html using a database. But those are normal things to do in a mapreduce.
the original article as well as that dbms2 link focus on "query" performance. Mapreduce is specifically not designed for live queries
"query" != "live query".
[MapReduce was not designed for] anything where the output is less than 10G or so
Where does the MapReduce architecture make any such assumption?
It is implausible to communicate with remote servers or parse html using a database. But those are normal things to do in a mapreduce.
Sure -- while it is quite possible to do such things using SQL UDFs, I can believe it isn't done very often. Nevertheless, there is considerable overlap between the two tools, and plenty of scope for comparison.
