the pseudo code for my update is

for i = 1 to n;
              insert k records into temp_table;

              update a set c1 = (select c1 from temp_table where
temp_table.pk = a.pk),                         c2  = ( select c2 from
temp_table where temp_table.pk = a.pk)
               where a.pk in (select pk from temp_table)

              delete from temp_table
              commit;
end for;

When the temp_table is created as a DB2 temporary table, the performance
degrades after each loop, but if temp_table is created as a regular DB2
table we see a consistent performance.

Also the number of row_reads (activity monitor) was found to be extremely
high.

The size of the table that is updated is around 70,000 and the temp_table
has 8192 rows.

Can anyone shed some light on what I am doing wrong? or if there are any
limitations on temporary table that I need to be aware of.

Thanks,
Sumanth