Re: Batch insert in CTAS/MatView code

On Thu, Sep 26, 2019 at 9:43 PM Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
wrote:

> On 2019-Sep-25, Asim R P wrote:
>
> > I reviewed your patch today. It looks good overall. My concern is that
> > the ExecFetchSlotHeapTuple call does not seem appropriate. In a generic
> > place such as createas.c, we should be using generic tableam API only.
> > However, I can also see that there is no better alternative. We need to
> > compute the size of accumulated tuples so far, in order to decide whether
> > to stop accumulating tuples. There is no convenient way to obtain the
> > length of the tuple, given a slot. How about making that decision solely
> > based on number of tuples, so that we can avoid ExecFetchSlotHeapTuple
> call
> > altogether?
>
> ... maybe we should add a new operation to slots, that returns the
> (approximate?) size of a tuple? That would make this easy. (I'm not
> sure however what to do about TOAST considerations -- is it size in
> memory that we're worried about?)
>
> Also:
>
> + myState->mi_slots_size >= 65535)
>
> This magic number should be placed in a define next to the other one,
> but I'm not sure that heapam.h is a good location, since surely this
> applies to matviews in other table AMs too.
>
> yes defining 65535 seems better. Let's fix this one later when having
more feedback. Thanks.