"Zeugswetter Andreas ADI SD" <Andreas.Zeugswetter@s-itsolutions.at> writes:
>> Note that you just raised the minimum bar for implementation of the
>> feature by a couple orders of magnitude.
> Yes, unfortunately. But don't you also think that this is what makes it
> a worthwhile feature ?
Well, my point is that taking automatic rewriting as a required feature
has at least two negative impacts:
* it rules out any form of lazy update, even though for many applications
an out-of-date summary view would be acceptable for some purposes;
* requiring MVCC consistency will probably hugely reduce the variety of
views that we can figure out how to materialize, and cost performance
even for the ones we can do at all.
It's not zero-cost, even if you consider implementation effort and
complexity as free (which I don't).
regards, tom lane