SQL problem -- batch vs. interactive

The following SQL statement runs in maybe 25 seconds in iSQL (V5R2, of course, 
current PTFs) but a batch run as embedded SQL it takes a couple hours:

select
   FLD001 ,
   FLD002 ,
   FLD003 ,
   FLD004 ,
   sum(
       (A.FLD005-FLD006)
     * (FLD007/A.FLD005)
      )
    as TOT ,
   FLD008 ,
   PERIOD
    from (
          select
             case
                when  FLD009 <  1040401  [:h1] then '1'
                when  FLD009 >  1040601  [:h2] then '4'
                when  FLD009 >= 1040501  [:h3] then '3'
                else  '2'
             end
              as PERIOD ,
             FLD001 ,
             FLD002 ,
             FLD003 ,
             FLD004 ,
             FLD009 ,
             FLD005 ,
             FLD006 ,
             FLD007 ,
             FLD008
              from
                 TBL01 a ,
                 TBL02 b
              where
                 a.FLD001 in ('FL' , '00') and
                 a.FLD005 <> 0 and
                 A.FLD010 =  ' ' and
                 a.FLD001 =  b.FLD011 and
                 a.FLD012 =  b.FLD013 and
                 exists(
                        select
                           *
                            from
                               TBL03 c
                            where
                               a.FLD001 =  c.FLD014 and
                               a.FLD015 =  c.FLD016 and
                               c.FLD017 <> 'Q' and
                               c.FLD018 in ('CC','CL ,'CP','CS','CU')
                       )
          ) as A
    group by
       FLD001 ,
       FLD002 ,
       FLD003 ,
       FLD004 ,
       FLD008 ,
       PERIOD

The [:hn] elements in the CASE clause simply mean the values are supplied by 
host variables. Regardless of whether proper indexes are available, what 
elements would cause such a major difference in run-time between environments? 
Run priority of interactive vs. batch is certainly possible, but the 
interactive is also during busy working hours and batch is at night during 
relatively quiet periods. Memory pools seem appropriate (approx 500MB for both 
batch and interactive during run periods).

At the moment, it's not a question of whether the statement could be better 
constructed. It's a question of curiosity about the difference.

Thanks for any discussion.

Tom Liotta



__________________________________________________________________
Introducing the New Netscape Internet Service. 
Only $9.95 a month -- Sign up today at http://isp.netscape.com/register

Netscape. Just the Net You Need. 

New! Netscape Toolbar for Internet Explorer
Search from anywhere on the Web and block those annoying pop-ups.
Download now at http://channels.netscape.com/ns/search/install.jsp