[postgis-devel] Bit setting to compress PostGIS geometries

[Paul Ramsey]

That's quite diabolical, and a nice freebie... and it brings us right
back to discussions of precision models.
Are they global, by table, by function call?
Smaller objects will make for faster access, so it's a win, I think we
should bring it in.
Incidentally, I've been doing some point-in-polygon benchmarking, and
the amount of time we spend just decompressing a toasted tuple in a
p-i-p calculation with a large polygon can be 95% of the CPU. Over and
over and over. Decompress it, check to see if it matches what's
cached, repeat.
For that use case, using "external" storage with a uncompressed header
and compressed payload would be a big win. Small is good.
P



On Fri, Feb 16, 2018 at 6:38 AM, Daniel Baston <dbaston at gmail.com> wrote:
> Hi,
>
> I've been experimenting with a cool technique to reduce the size of PostGIS
> geometries by setting insignificant bits to zero, which makes the geometry
> objects more compressible.
>
> I described the technique in a post here, which shows some test results:
> http://www.danbaston.com/posts/2018/02/15/optimizing-postgis-geometries.html
>
> I'm on the fence about whether something like this has a place in the
> PostGIS core, but am leaning towards "yes." What do others think?
>
> Dan
>
>
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