I have a program which when ran in development takes time for about 7 mins. It accesss mara table and reads material value from that. Total no of recorsd are about 150,000. When I run the same program in Production it takes 6.5 hrs where as the no of recorsds are 300,000. The program has nested select statements. I know that nested select statements are a barrier to performance to the program but how come such a huge difference ? Is there any thing to be taken care of indexes ? The functioanl member says they had a similar problem earlier too, and rebuilding the indexes has resolved the issue? Is it true ? are indexes a concern in this regard ?