Hello Yuri, PDEP is indeed first thing that comes up when you start googling z-curve and bit interleaving :) We had the code with z-curve generating PDEP instruction in PostGIS, and dropped it since. In sorting, we now utilize sort support / prefix search, and key generated as Hilbert curve, with fine tuning it for different projections' geometric properties.
>From this patch the most valuable thing for us is the sorting build infrastructure itself. Maybe to get it a bit more understandable for people not deep in geometry it makes sense to first expose the btree_gist datatypes to this thing? So that btree_gist index on integer will be built exactly the same way the btree index on integer is built. This will also get everyone a reference point on the bottlenecks and optimality of patch. On Fri, Apr 3, 2020 at 10:56 AM Yuri Astrakhan <yuriastrak...@gmail.com> wrote: > > Awesome addition! Would it make sense to use x86's BMI2's PDEP instruction, > or is the interleave computation too small of a percentage to introduce > not-so-easy-to-port code? Also, I think it needs a bit more documentation to > explain the logic, i.e. a link to > https://stackoverflow.com/questions/39490345/interleave-bits-efficiently ? > Thx for making it faster :) -- Darafei Praliaskouski Support me: http://patreon.com/komzpa
