Hi, On 2019-09-26 10:43:27 -0300, Alvaro Herrera 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.
Indeed. > > 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? Hm, I'm not convinced that it's worth adding that as a dedicated operation. It's not that clear what it'd exactly mean anyway - what would it measure? As referenced in the slot? As if it were stored on disk? etc? I wonder if the right answer wouldn't be to just measure the size of a memory context containing the batch slots, or something like that. > 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?) The in-memory size is probably fine, because in all likelihood the toasted cols are just going to point to on-disk datums, no? > 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. Right. I think it'd be better to move this into an AM independent place. Greetings, Andres Freund
