Netezza LAST_VALUE filter

Question

Am trying to create a NETEZZA table which has only the most recent records for a particular key - eg imagine a table (MYTABLE) as follows:

Col1 Col2 TIMESTAMP
xxxx xxxx 13:45
xxxx xxxx 13:46
xxxx yyyy 10:00

I would like to return a table as follows:

Col1 Col2 TIMESTAMP
xxxx xxxx 13:46
xxxx yyyy 10:00

I'm guessing I need some code along the lines of:

  Create table MYNEWTABLE as
    select *
    from MYTABLE
    WHERE rowid in
    (
    SELECT LAST_VALUE(rowid)
    OVER (PARTITION BY COL1, COL2
          ORDER BY TIMESTAMP)
          FROM MYTABLE
    )
    ORDER BY COL1,COL2
    distribute on (COL1)

However this isn't really working, can anyone please advise? (specifically how to filter the table by the last value of timestamp within the col1 / col2 partition)

Answer 1

Got it - finally! rowid was a misnomer. Credit to Shawn Fox of Netezza Community for inspiration.

  Create table MYNEWTABLE as select * from
    (select *
            ,row_number() over (
                 partition by COL1, COL2 order by TIMESTAMP desc
                               ) row
       from MYTABLE 
    ) x
    WHERE x.row=1
    distribute on (COL1)