Re: LF on 2 files with 'UNION'

[Pete Hall <pbhall@xxxxxxxxxxxxx>]

At 11:48 11/06/2002, Sudha Ramanujan wrote:
> I am trying to fine tune a performance issue I have in my project where I
> am using a 'Union' over 2 large files.  This returns me a distinct result
> of selected fields from both the files, which is wonderful.  But the time
> taken is quite significant since each call creates a union. I cannot
> create a view on Union, so I am trying to find an easier way to do this
> like say via maybe a LF.  Is this possible?  Else, creating 2 separate
> indexes/views on the 2 files on the selected fields will help?
Sudha,

Why can you not create a view with a union? Is that a company policy or
something? Create View will certainly work with a union. More significant,
however is the availability of appropriate indexes to implement the query.
If you can, run the query from operations navigator visual explain, or if
you can't do that, just run the job in debug and read the joblog to see the
query optimizer recommendations. Add whatever indexes are indicated.

hth


Pete Hall
pbhall@ameritech.net
http://www.ameritech.net/users/pbhall/index.html