I'm pretty sure there are at least a few bugs in that article. The problem described below goes away if "rank" is added to the outer select statement. If there's one error I suppose there may be others. Although I have gotten the query to run, I'm not getting properly ranked results yet. I'm still working on it.
On Apr 2, 2013, at 10:03 , Keith Wiley wrote: > On Apr 1, 2013, at 16:12 , Alexander Pivovarov wrote: > >> http://ragrawal.wordpress.com/2011/11/18/extract-top-n-records-in-each-group-in-hadoophive/ > > Is there any possibility there is a bug in Ritesh Agrawal's query statement > from that article? I created a test table with the exact column names from > the example in the article and used a minimally altered version of the > command (I removed the where clause to simplify things a bit) and got an > error which suggests there is something slightly wrong with the command (or > perhaps the table has to be configured a special way). Here's what I get > when I almost perfectly duplicate that example: > > hive> describe test; > OK > user string > category string > value int > Time taken: 0.082 seconds > ================================================== > hive> select * from test; > OK > user1 cat1 1 > user1 cat1 2 > user1 cat1 3 > user1 cat2 10 > user1 cat2 20 > user1 cat2 30 > user2 cat1 11 > user2 cat1 21 > user2 cat1 31 > user2 cat2 5 > user2 cat2 6 > user2 cat2 7 > Time taken: 0.202 seconds > ================================================== > hive> SELECT user, category, value >> FROM ( >> SELECT user, category, rank(user) as rank, value >> FROM test >> DISTRIBUTE BY user >> SORT BY user, value desc >> ) a >> WHERE rank > 1 >> ORDER BY user, rank; > FAILED: Error in semantic analysis: Line 9:15 Invalid table alias or column > reference 'rank': (possible column names are: _col0, _col1, _col2) > hive> > > ________________________________________________________________________________ > Keith Wiley kwi...@keithwiley.com keithwiley.com > music.keithwiley.com > > "What I primarily learned in grad school is how much I *don't* know. > Consequently, I left grad school with a higher ignorance to knowledge ratio > than > when I entered." > -- Keith Wiley > ________________________________________________________________________________ > ________________________________________________________________________________ Keith Wiley kwi...@keithwiley.com keithwiley.com music.keithwiley.com "Yet mark his perfect self-contentment, and hence learn his lesson, that to be self-contented is to be vile and ignorant, and that to aspire is better than to be blindly and impotently happy." -- Edwin A. Abbott, Flatland ________________________________________________________________________________
