Re: Varying fields and SQL predicate LIKE

[Vern Hamberg <vhamberg@xxxxxxxxxxx>]

Charles

First blush - do a DSPPFM F10 F11 and verify that the length in the 
first 2 bytes actually reflects the trimmed length. When I've needed to 
change to varying in the DB, I've used the STRIP function in an SQL 
UPDATE statement with no WHERE clause - unless you wanted to use a 
condition that length(field) <> length(strip(field))!

HTH
Vern

On 7/22/2010 10:12 AM, Charles Wilt wrote:
> All,
>
> I've got a 3.1 million row table with a 25 character field that holds
> a street address, ex. '123 MAIN ST.'
>
> We currently perform seraches by address like so:
> select *
> from myTable
> where address like '%MAIN%'
>
> Given the leading '%', I know the search will require a full table
> (perhaps full index) scan.
>
> Given that the average TRIM'd length of the data in the field is 16
> and that RPG works much faster with varying fields.  I was thinking
> that if I changed the field to varying, the DB wouldn't have any
> trailing blanks to compare too and thus my searches should be about
> 36% faster...
>
> However, I'm not seeing a 36% improvement.  In fact, it appears that
> performance is worse by a couple of percent!
>
> Any thoughts as to why this is the case?
>
> I've double checked the following:
> - The varying field is set ALLOCATE(25)
> - The data in the varying field is TRIM'd
>
> Thanks!
> Charles
>