Re: New Table Access Methods for Multi and Single Inserts

On Fri, Dec 18, 2020 at 2:14 AM Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
> On Thu, Dec 17, 2020 at 04:35:33PM +0530, Bharath Rupireddy wrote:
> > > You made the v2 insert interface a requirement for all table AMs.
> > > Should it be optional, and fall back to simple inserts if not implemented ?
> >
> > I tried to implement the APIs mentioned by Andreas here in [1]. I just
> > used v2 table am APIs in existing table_insert places to show that it
> > works. Having said that, if you notice, I moved the bulk insert
> > allocation and deallocation to the new APIs table_insert_begin() and
> > table_insert_end() respectively, which make them tableam specific.
>
> I mean I think it should be optional for a tableam to support the optimized
> insert routines. Here, you've made it a requirement.
>
> + Assert(routine->tuple_insert_begin != NULL);
> + Assert(routine->tuple_insert_v2 != NULL);
> + Assert(routine->multi_insert_v2 != NULL);
> + Assert(routine->multi_insert_flush != NULL);
> + Assert(routine->tuple_insert_end != NULL);

+1 to make them optional. I will change.

> +static inline void
> +table_multi_insert_v2(TableInsertState *state, TupleTableSlot *slot)
> +{
> + state->rel->rd_tableam->multi_insert_v2(state, slot);
> +}
>
> If multi_insert_v2 == NULL, I think table_multi_insert_v2() would just call
> table_insert_v2(), and begin/flush/end would do nothing. If
> table_multi_insert_v2!=NULL, then you should assert that the other routines are
> provided.

What should happen if both multi_insert_v2 and insert_v2 are NULL?
Should we error out from table_insert_v2()?

> Are you thinking that TableInsertState would eventually have additional
> attributes which would apply to other tableams, but not to heap ? Is
> heap_insert_begin() really specific to heap ? It's allocating and populating a
> structure based on its arguments, but those same arguments would be passed to
> every other AM's insert_begin routine, too. Do you need a more flexible data
> structure, something that would also accomodate extensions? I'm thinking of
> reloptions as a loose analogy.

I could not think of other tableam attributes now. But +1 to have that
kind of flexible structure for TableInsertState. So, it can have
tableam type and attributes within the union for each type.

> I moved the bulk insert allocation and deallocation to the new APIs table_insert_begin()
> and table_insert_end() respectively, which make them tableam specific.
> Currently, the bulk insert state is outside and independent of
> tableam. I think we should not make bulk insert state allocation and
> deallocation tableam specific.

Any thoughts on the above point?

With Regards,
Bharath Rupireddy.
EnterpriseDB: http://www.enterprisedb.com