I noticed a very strange performance issue after I pre-create daily partitions for the next month on a table that has a very large insert volume (30 million a day). After the partitions are created..the inserts seem to slow down. I verifiied that this was the issue by dropping the partitions...When I dropped the pre-created partitions..the performance issue disappeared. Looks like you cannot have too many partitions (in this case..I had a total of 35 partitions when the performance issue was noticed)
Postgres version is 8.1.9 on a 8 core Red Hat linux box with a Raid 10 configured hard frive set up that has 6 15K disks . The load factor on the box is very low ..just the insert performance suffers after the partition creation.