On Sat, Mar 3, 2018 at 4:53 PM, David Rowley <david.row...@2ndquadrant.com> wrote: > On 3 March 2018 at 05:30, Darafei "Komяpa" Praliaskouski <m...@komzpa.net> > wrote: >> Our options were: >> >> - partitioning. Not entirely trivial when your id is uuid. To get visible >> gains, we need to make sure each driver gets their own partition. That would >> leave us with 50 000(+) tables, and rumors say that in that's what is done >> in some bigger taxi service, and relcache then eats up all the RAM and >> system OOMs. > > It's a good job someone invented HASH partitioning then. > > It would be interesting to hear how your benchmarks go using current > master + the faster partition pruning patchset [1]. Currently, HASH > partitioning does exist in master, just there's no partition pruning > for the non-matching partitions, which is why you need [1]. > > I think trying with something like 500-1000 partitions might be a good > place to start.
I don't think that will actually help much. 1000 partitions means each partition gets data from ~50 vehicles. A 60 tuples per page each page in the partitioned able will contain on average 1.2 interesting tuples. So you still have almost one page read per row. Regards, Ants Aasma -- +43-670-6056265 Cybertec Schönig & Schönig GmbH Gröhrmühlgasse 26, A-2700 Wiener Neustadt Web: https://www.cybertec-postgresql.com
