Re: Skip partition tuple routing with constant partition key

On Thu, May 20, 2021 at 9:20 AM tsunakawa.takay@fujitsu.com
<tsunakawa.takay@fujitsu.com> wrote:
> From: Amit Langote <amitlangote09@gmail.com>
> > On Tue, May 18, 2021 at 11:11 AM houzj.fnst@fujitsu.com
> > <houzj.fnst@fujitsu.com> wrote:
> > > For some big data scenario, we sometimes transfer data from one table(only
> > store not expired data)
> > > to another table(historical data) for future analysis.
> > > In this case, we import data into historical table regularly(could be one day or
> > half a day),
> > > And the data is likely to be imported with date label specified, then all of the
> > data to be
> > > imported this time belong to the same partition which partition by time range.
> >
> > Is directing that data directly into the appropriate partition not an
> > acceptable solution to address this particular use case?  Yeah, I know
> > we should avoid encouraging users to perform DML directly on
> > partitions, but...
>
> Yes, I want to make/keep it possible that application developers can be unaware of partitions.  I believe that's why
David-san,Alvaro-san, and you have made great efforts to improve partitioning performance.  So, I'm +1 for what Hou-san
istrying to achieve. 

I'm very glad to see such discussions on the list, because it means
the partitioning feature is being stretched to cover wider set of use
cases.

> Is there something you're concerned about?  The amount and/or complexity of added code?

IMHO, a patch that implements caching more generally would be better
even if it adds some complexity.  Hou-san's patch seemed centered
around the use case where all rows being loaded in a given command
route to the same partition, a very specialized case I'd say.

Maybe we can extract the logic in Hou-san's patch to check the
constant-ness of the targetlist producing the rows to insert and find
a way to add it to the patch I posted such that the generality of the
latter's implementation is not lost.

--
Amit Langote
EDB: http://www.enterprisedb.com