Pierre -
Are you sure the databases are identical? Including indicies? The only
significant difference I can see is the choice of index by the 6.5 plan
for the scan on pcat:
> V6.5
> Index Scan using pcat_dcat_id_idx on pcat c (cost=264.24 size=4465 width=4)
>
> V6.4
> Index Scan using pcat_prod_id_idx on pcat c (cost=2.00 size=4457 width=4)
Strangely enough, the estimated total cost difference is about the same ratio.
--
Ross J. Reedstrom, Ph.D., <reedstrm@rice.edu>
NSBRI Research Scientist/Programmer
Computer and Information Technology Institute
Rice University, 6100 S. Main St., Houston, TX 77005