There were more large constants that needed UINT64CONST. And one variable
was declared as "int", when it needed to be uint64. These bugs were only
visible on 32-bit systems; clearly I should've tested on one, given that
this code does a lot of work with 64-bit integers.
Also, in the test "huge distances" test, the code created some values with
random distances between them, but the test logic didn't take into account
the possibility that the random distance was exactly 1. That never actually
happens with the seed we're using, but let's be tidy.
The set is implemented as a B-tree, with a compact representation at leaf
items, using Simple-8b algorithm, so that clusters of nearby values use
less memory.
The IntegerSet isn't used for anything yet, aside from the test code, but
we have two patches in the works that would benefit from this: A patch to
allow GiST vacuum to delete empty pages, and a patch to reduce heap
VACUUM's memory usage, by storing the list of dead TIDs more efficiently
and lifting the 1 GB limit on its size.
This includes a unit test module, in src/test/modules/test_integerset.
It can be used to verify correctness, as a regression test, but if you run
it manully, it can also print memory usage and execution time of some of
the tests.
Author: Heikki Linnakangas, Andrey Borodin
Reviewed-by: Julien Rouhaud
Discussion: https://www.postgresql.org/message-id/b5e82599-1966-5783-733c-1a947ddb729f@iki.fi
Heikki Linnakangas