On Fri, May 25, 2012 at 9:04 AM, Craig James <cja...@emolecules.com> wrote:
> 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. > This is somewhat disturbing. I need to throw out a question I hope for an answer. Has anyone ever witnessed similar behavior with a large number of relations? Slow? Corruption? -Greg
