Re: Should TIDs be typbyval = FLOAT8PASSBYVAL to speed up CREATE INDEX CONCURRENTLY?

Peter Geoghegan <pg(at)heroku(dot)com> writes:
> I noticed that the TID type is cataloged as typbyval = f, despite the
> fact that it is 6 bytes, and so could be made typbyval = t on 64-bit
> platforms (i.e. typbyval = FLOAT8PASSBYVAL) with a little work.

I'm not sure that it would be just "a little work" --- I suspect that
the idea that pass-by-val types are 1, 2, 4, or 8 bytes is embedded in
a fair number of places, including alignment macros in which any added
complexity would have a large distributed cost.

> This matters because a major cost during CREATE INDEX CONCURRENTLY is
> a TID-based datum sort (this is probably most of the cost over and
> above a conventional CREATE INDEX).

Might be better to hack a special case right there (ie, embed TIDs into
int8s and sort the int8s) rather than try to change the type's SQL
declaration.

regards, tom lane