Re: Pluggable Storage - Andres's take

On Wed, Oct 3, 2018 at 3:16 PM Andres Freund <andres(at)anarazel(dot)de> wrote:

> On 2018-09-27 20:03:58 -0700, Andres Freund wrote:
> > On 2018-09-28 12:21:08 +1000, Haribabu Kommi wrote:
> > > Here I attached further cleanup patches.
> > > 1. Re-arrange the GUC variable
> > > 2. Added a check function hook for default_table_access_method GUC
> >
> > Cool.
> >
> >
> > > 3. Added a new hook validate_index. I tried to change the function
> > > validate_index_heapscan to slotify, but that have many problems as it
> > > is accessing some internals of the heapscandesc structure and accessing
> > > the buffer and etc.
> >
> > Oops, I also did that locally, in a way. I also made a validate a
> > callback, as the validation logic is going to be specific to the AMs.
> > Sorry for not pushing that up earlier. I'll try to do that soon,
> > there's a fair amount of change.
>
> I've pushed an updated version, with a fair amount of pending changes,
> and I hope all your pending (and not redundant, by our concurrent
> development), patches merged.
>

Yes, All the patches are merged.

There's currently 3 regression test failures, that I'll look into
> tomorrow:
> - partition_prune shows a few additional Heap Blocks: exact=1 lines. I'm
> a bit confused as to why, but haven't really investigated yet.
> - fast_default fails, because I've undone most of 7636e5c60fea83a9f3c,
> I'll have to redo that in a different way.
> - I occasionally see failures in aggregates.sql - I've not figured out
> what's going on there.
>

I also observed the failure of aggregates.sql, will look into it.

> Amit Khandekar said he'll publish a new version of the slot-abstraction
> patch tomorrow, so I'll rebase it onto that ASAP.
>

OK.
Here I attached two new API patches.
1. Set New Rel File node
2. Create Init fork

There is an another patch of "External Relations" in the older patch set,
which is not included in the current git. That patch is of creating
external relations by the extensions for their internal purpose. (Columnar
relations for the columnar storage). This new relkind can be used for
those relations, this way it provides the difference between normal and
columnar relations. Do you have any other idea of supporting those type
of relations?

And also I want to create a new API for heap_create_with_catalog
to let the pluggable storage engine to create additional relations.
This API is not required for every storage engine, so instead of moving
the entire function as API, how about adding an API at the end of the
function and calls only when it is set like hook functions? In case if the
storage engine doesn't need any of the heap_create_with_catalog
functionality then creating a full API is better.

Comments?

My next planned steps are a) to try to commit parts of the
> slot-abstraction work b) to try to break out a few more pieces out of
> the large pluggable storage patch.
>

OK. Let me know your views on the part of the pieces that are stable,
so that I can separate them from larger patch.

Regards,
Haribabu Kommi
Fujitsu Australia