[Qgis-user] SpatiaLite data rendered slowly

[Dan Lyke]

On Mon, Sep 14, 2015 at 7:55 AM, Árni Geirsson <arni at alta.is> wrote:
> One observation regarding this problem: Both the shapefile and SpatiaLite
> database are on a NAS box. If I move the SpatiaLite file to a local drive,
> it renders instantly like the shapefile. So the question is: What is it
> about being stored on a NAS box that throttles down the speed of SpatiaLite
> but does not affect shapefiles?

It is likely that in processing your query, SpatiaLite is doing a
*lot* of individual disk I/O, where the Shapefile read is happening as
a few large I/O operations.

If you need the database on a distributed server, you're probably way
better off using PostGIS, where all of the disk I/O can occur on a
device local to the query computing and then get sent back as one
large chunk, rather than that I/O having to occur over a network, with
network semantics (especially if there's any file locking happening).