[postgis-users] degree vs. metric projection performance?

[Nicolas Ribot]

> Hi all,
>
> I am developing an application that uses google maps as a front-end
> and postgis in the backend. Currently, we are using google mercator
> projection (SRID = 4326) for all geometries in the database. But,
> since we perform lots of geometric operations with these objects
> within the database, I am concerned about performance issues.
>

Are you transforming your data before doing the geometric operations or not ?
You should, as PostGIS does not know how to work with geographic data.

> Wouldn't it be better if instead of a mercator projection, we stored
> all information in metric-based values?
> If so, is there any metric-based projection that works in any part of the world?
>

No, there isn't such a projection. It is not possible to project a
spheroid on a plane globally without losing some information (angle;
surface, ...).
You would have to reproject locally your data into a planar system,
work on it, and transform back to WGS84.

By the way, are the Google Mercator and WGS84 systems equivalent