On Fri, Jun 19, 2020 at 12:34 PM Laurenz Albe <laurenz.albe@xxxxxxxxxxx> wrote:
On Fri, 2020-06-19 at 12:12 +0530, Srinivasa T N wrote:
> On Fri, Jun 19, 2020 at 11:44 AM David Rowley <dgrowleyml@xxxxxxxxx> wrote:
> > On Fri, 19 Jun 2020 at 17:42, Srinivasa T N <seenutn@xxxxxxxxx> wrote:
> > > After seeing the below, I feel partitioning is not working properly or it maybe case that my understanding is wrong. Can somebody explain me what is happening?
> >
> > It's your understanding that's not correct. The value of is passed
> > through a hash function and the partition is selected based partition
> > matching the remainder value after dividing the return value of the
> > hash function by the largest modulus of any partition.
> >
> > That might surprise you, but how would you select which partition a
> > varchar value should go into if you didn't use a hash function.
> >
> > David
>
> How can I see the output of hash function that is used internally?
In the case of "integer", the hash function is "pg_catalog"."hashint4".
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
I guess output formatting is wrong, any help?
postgres=# select pg_catalog.hashint4(7);
hashint4 ------------
-978793473
(1 row)
Regards,
Seenu.
