On 2 March 2017 at 13:03, amul sul <sula...@gmail.com> wrote: > create table foo (a integer, b text) partition by hash (a); > create table foo1 partition of foo with (modulus 4, remainder 0); > create table foo2 partition of foo with (modulus 8, remainder 1); -- legal, > modulus doesn't need to match > create table foo3 partition of foo with (modulus 8, remainder 4); -- > illegal, overlaps foo1
Instead of using modulus, why not just divide up the range of hash keys using ranges? That should be just as good for a good hash function (effectively using the high bits instead of the low bits of the hash value). And it would mean you could reuse the machinery for list partitioning for partition exclusion. It also has the advantage that it's easier to see how to add more partitions. You just split all the ranges and (and migrate the data...). There's even the possibility of having uneven partitions if you have a data distribution skew -- which can happen even if you have a good hash function. In a degenerate case you could have a partition for a single hash of a particularly common value then a reasonable number of partitions for the remaining hash ranges. -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
