[PERFORM] ORDER BY and LIMIT with SubSelects

[Ron St-Pierre]

I need to get 200 sets of the most recent data from a table for further 
processing, ordered by payDate. My
current solution is to use subselects to:
1 - get a list of unique data
2 - get the 200 most recent records (first 200 rows, sorted descending)
3 - sort them in ascending order

SELECT SSS.* FROM
(SELECT SS.* FROM
  (SELECT DISTINCT ON (nonUniqField)
   first, second, third, cost, payDate, nonUniqField
   FROM histdata
   WHERE userID = 19048 AND cost IS NOT NULL
  )
 SS  
 ORDER BY SS.payDate DESC LIMIT 200
) SSS
ORDER BY payDate;

My question is in regards to steps 2 and 3 above. Is there some way that 
I can combine both steps into one to save some time?

PostgreSQL 7.4beta2 on i686-pc-linux-gnu, compiled by GCC 2.95.4

Thanks
Ron


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