On Fri, May 25, 2012 at 4:58 AM, Greg Spiegelberg <gspiegelb...@gmail.com>wrote:
> On Sun, May 13, 2012 at 10:01 AM, Craig James <cja...@emolecules.com>wrote: > >> >> On Sun, May 13, 2012 at 1:12 AM, Віталій Тимчишин <tiv...@gmail.com>wrote: >> >>> >>> The sequences AFAIK are accounted as relations. Large list of relations >>> may slowdown different system utilities like vacuuming (or may not, depends >>> on queries and indexes on pg_class). >>> >> >> Not "may slow down." Change that to "will slow down and possibly >> corrupt" your system. >> >> In my experience (PG 8.4.x), the system can handle in the neighborhood of >> 100,000 relations pretty well. Somewhere over 1,000,000 relations, the >> system becomes unusable. It's not that it stops working -- day-to-day >> operations such as querying your tables and running your applications >> continue to work. But system operations that have to scan for table >> information seem to freeze (maybe they run out of memory, or are >> encountering an O(N^2) operation and simply cease to complete). >> > > Glad I found this thread. > > Is this 1M relation mark for the whole database cluster or just for a > single database within the cluster? > I don't know. When I discovered this, our system only had a few dozen databases, and I never conducted any experiments. We had to write our own version of pg_dump to get the data out of the damaged system, and then reload from scratch. And it's not a "hard" number. Even at a million relation things work ... they just bog down dramatically. By the time I got to 5 million relations (a rogue script was creating 50,000 tables per day and not cleaning up), the system was effectively unusable. Craig > Thanks, > -Greg > >
