Andrew Dunstan <[EMAIL PROTECTED]> writes: > Maybe we need to split this into two pieces, given Tom's legitimate > concern about semaphore use. How about we increase the allowed range for > shared_buffers and max_fsm_pages, as proposed in my patch, and leave the > max_connections issue on the table? I also wondered if instead of first > setting max_connections and then shared_buffers/max_fsm_pages, we should > try to scale them in synch somehow.
The existing initdb code actually does try to scale them in sync to some extent --- take a closer look at the arguments being passed during the max-connections test phase. It won't choose a large max_connections unless it can simultaneously get 5 times that many shared_buffers. I think this probably needs to be more aggressive though. In a situation of limited SHMMAX it's probably more important to keep shared_buffers as high as we can than to get a high max_connections. We could think about increasing the 5x multiplier, adding Min and/or Max limits, or some combination. BTW, I fat-fingered the calculations I was doing last night --- the actual shmem consumption in CVS tip seems to be more like 17K per max_connection increment, assuming max_locks_per_connection = 64. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match