On Wed, 2005-11-16 at 11:47, Luke Lonergan wrote: > Scott, Some cutting for clarity... I agree on the OLTP versus OLAP discussion. > Here are the facts so far: > * Postgres can only use 1 CPU on each query > * Postgres I/O for sequential scan is CPU limited to 110-120 > MB/s on the fastest modern CPUs > * Postgres disk-based sort speed is 1/10 or more slower than > commercial databases and memory doesn’t improve it (much) But PostgreSQL only spills to disk if the data set won't fit into the amount of memory allocated by working_mem / sort_mem. And for most Business analysis stuff, this can be quite large, and you can even crank it up for a single query. I've written reports that were horrifically slow, hitting the disk and all, and I upped sort_mem to hundreds of megabytes until it fit into memory, and suddenly, a slow query is running factors faster than before. Or did you mean something else by "disk base sort speed"??? ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
