Hi,
I am new to datastage, learning the basic concepts of all the stages.
Can anyone help me,when to use sparse lookup? What is the difference between normal & sparse look up? And Also how to do a 'Cross Join'?
Sparse look up
Moderators: chulett, rschirm, roy
Sparse look up
Thanks & Regards,
Badga.
Badga.
A "normal" lookup will read all of the reference data into memory to speed up subsequent lookups. A "sparse" lookup will perform a read of the reference for each data row. The latter is best when there are a large number of reference rows and just a few data rows, or where the reference data values can change during the course of a single run.
A "cross join" is an inner join where the condition is always met.
A "cross join" is an inner join where the condition is always met.
<a href=http://www.worldcommunitygrid.org/team/ ... TZ9H4CGVP1 target="WCGWin">
</a>
</a>
Yes (normal lookup loaded into RAM)
Yes (specify normal or sparse lookup in the source DB stage)
Yes (specify normal or sparse lookup in the source DB stage)
<a href=http://www.worldcommunitygrid.org/team/ ... TZ9H4CGVP1 target="WCGWin">
</a>
</a>
-
- Participant
- Posts: 54607
- Joined: Wed Oct 23, 2002 10:52 pm
- Location: Sydney, Australia
- Contact:
Sparse lookup is only supported against certain databases (DB2 and Oracle, if memory serves), and the option to use it is actually made on the database stage rather than in the Lookup stage.
IBM Software Services Group
Any contribution to this forum is my own opinion and does not necessarily reflect any position that IBM may hold.
Any contribution to this forum is my own opinion and does not necessarily reflect any position that IBM may hold.
I know its old post, but the information is wrong, just want to highlightArndW wrote:A "cross join" is an inner join where the condition is always met.
CROSS JOIN returns the Cartesian product of rows from tables in the join. In other words, it will produce rows which combine each row from the first table with each row from the second table.