Re: getting rownum 500000 - 500050 from a database

From: Jerry Gitomer <jgitomer_at_erols.com>
Date: Tue, 16 Nov 1999 00:23:46 -0500
Message-ID: <80qpns$ipl$1@autumn.news.rcn.net>

Hi Marc,

    What you are trying to do won't work! Oracle may or may not store data at the end of a data file. In fact, if rows have been deleted from a table new rows may be stored in the space formerly occupied by the deleted rows. In addition, when doing full table scans, there is no guarantee that Oracle will start at the beginning of the file and read consecutive blocks. I seem to recall (and my memory may be faulty or the source I heard this from may be wrong, but....) if some blocks of a table are in memory and a full scan is required Oracle will start with the blocks that are already in memory. This means that the rownum of the data read from memory -- no matter where located in the table -- will have the lowest rownums.

    If you must retrieve data sequentially based on order of storage you will have to add a column to your table and then use a sequence to increment it as rows are added to the table.

hth
jerry gitomer

Marc Parkinson wrote in message <3830B8E4.DB5D4B3B_at_uswest.net>...

|I need to get row numbers 500000 through 500050 from a database.
|I also need to do an order by clause before I retreive the data.
|
|Any ideas on how to do this other then reading the fir 500000
rows of
|data??
|
|
|thanks
|
|Marc Parkinson
|marcpark_at_uswest.net
|
|
Received on Mon Nov 15 1999 - 23:23:46 CST