Qingqing Zhou wrote:
Oracle 9 uses the grammar like this:

    CREATE INDEX ... [ COMPRESS <number_of_first_columns> ]

So it gives the flexibility of choosing optimal number of coulumns to the user. The script mentioned in the article guesses the optimal number by estimating the size of each choice. But I am thinking we can do it better: (1) we don't require that the compressed number of columns on each page are the same; (2) when we build up index bottom-up, we can determine this number for each page automatically by maximizing the number of items within a page.

Are there any gains in eliminating duplicate values in result-sets? I'd guess that many/most large result-sets are sorted which should make it possible to get away with a "same as last row" marker when the whole set is returned to a client.

Of course, this is where someone turns around and tells me we do this already :-)

--
  Richard Huxton
  Archonet Ltd

---------------------------(end of broadcast)---------------------------
TIP 6: explain analyze is your friend

Reply via email to