Re: Skip partition tuple routing with constant partition key

Hou-san,

On Thu, May 27, 2021 at 3:56 PM houzj(dot)fnst(at)fujitsu(dot)com
<houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> From: Amit Langote <amitlangote09(at)gmail(dot)com>
> Sent: Thursday, May 27, 2021 1:54 PM
> > On Thu, May 27, 2021 at 11:47 AM houzj(dot)fnst(at)fujitsu(dot)com
> > <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> > > About teaching relcache about caching the target partition.
> > >
> > > David-san suggested cache the partidx in PartitionDesc.
> > > And it will need looping and checking the cached value at each level.
> > > I was thinking can we cache a partidx list[1, 2 ,3], and then we can
> > > follow the list to get the last partition and do the partition CHECK
> > > only for the last partition. If any unexpected thing happen, we can
> > > return to the original table and redo the tuple routing without using the
> > cached index.
> > > What do you think ?
> >
> > Where are you thinking to cache the partidx list? Inside PartitionDesc or some
> > executor struct?
>
> I was thinking cache the partidx list in PartitionDescData which is in relcache, if possible, we can
> use the cached partition between statements.

Ah, okay. I thought you were talking about a different idea. How and
where would you determine that a cached partidx value is indeed the
correct one for a given row?

Anyway, do you want to try writing a patch to see how it might work?

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