The statistics-based cost estimation patch for range types broke that, by
incorrectly assuming that the left operand of all range oeprators is a
range. That lead to a "type x is not a range type" error. Because it took so
long for anyone to notice, add a regression test for that case.
We still don't do proper statistics-based cost estimation for that, so you
just get a default constant estimate. We should look into implementing that,
but this patch at least fixes the regression.
Spotted by Tom Lane, when testing query from Josh Berkus.
The estimates are based on the existing lower bound histogram, and a new
histogram of range lengths.
Bump catversion, because the range length histogram now needs to be present
in statistic slot kind 6, or you get an error on @> and <@ queries. (A
re-ANALYZE would be enough to fix that, though)
Alexander Korotkov, with some refactoring by me.
This reduces unnecessary exposure of other headers through htup.h, which
is very widely included by many files.
I have chosen to move the function prototypes to the new file as well,
because that means htup.h no longer needs to include tupdesc.h. In
itself this doesn't have much effect in indirect inclusion of tupdesc.h
throughout the tree, because it's also required by execnodes.h; but it's
something to explore in the future, and it seemed best to do the htup.h
change now while I'm busy with it.
This enables selectivity estimation of the <<, >>, &<, &> and && operators,
as well as the normal inequality operators: <, <=, >=, >. "range @> element"
is also supported, but the range-variant @> and <@ operators are not,
because they cannot be sensibly estimated with lower and upper bound
histograms alone. We would need to make some assumption about the lengths of
the ranges for that. Alexander's patch included a separate histogram of
lengths for that, but I left that out of the patch for simplicity. Hopefully
that will be added as a followup patch.
The fraction of empty ranges is also calculated and used in estimation.
Alexander Korotkov, heavily modified by me.
