[postgis-devel] topology : new index on node table

[Rémi Cura]

Almost a 10x factor, really nice !
Cheers,
Rémi-C


2014-07-30 11:38 GMT+02:00 Sandro Santilli <strk at keybit.net>:

> On Wed, Jul 30, 2014 at 11:29:00AM +0200, Sandro Santilli wrote:
>
> > There's a reference dataset produced some time ago by a user who resulted
> > in a fix making topology creation much faster:
> > http://lists.osgeo.org/pipermail/postgis-devel/2014-January/024078.html
> >
> > I still have a couple of diagrams showing population time before/after
> > that are waiting for a blog post that I never find the time to write...
>
> Just a sneak preview of the blog post that might never be written
>
> Queries:
>
>  SELECT ST_CreateTopoGeo('million_poly_topo1', ST_Collect(geom))
>  FROM ( SELECT geom from million_poly_topo1 order by gid limit 160000) as
> f;
>
>  SELECT TopoGeo_addPolygon('million_poly_topo1', ST_GeometryN(geom,1))
>  FROM ( SELECT geom from million_poly_topo1 order by gid limit 160000) as
> f;
>
> Output topology has:
>
>  160167 nodes, 160167 edges, 160167 faces
>
> Times:
>
>  a: before starting
>  b: Ensure face splitting algorithm uses the edge index (#2610)
>  c: Drop all calls to geometry::text during topology population (#2616)
>
>       ST_CreateTopoGeo     TopoGeo_addPolygon
>     +-------------------+--------------------+
>  a  |    38352283.535   |    38375126.950    |
>  b  |    12088554.776   |     9644736.277    |
>  c  |    11963757.923   |     4984225.402    |
>
> I've a table with more numbers, with limits from 5000 to 160000.
> The index change would make another configuration (d, I guess).
>
> Please please please file the ticket, maybe referencing this thread
> and #2610 and #2616 as I'd really love to grow the optimizations further
>
> --strk;
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