[postgis-users] Performance compared to large shapefiles?

[Jeff Dege]

Someone pointed me to PostGIS as being a tool worth considering.

We've done our mapping so far with various extensions built on top of
UMN MapServer (ka-map and openlayers).  The GIS data we've been storing
in shapfiles.

We're finding it very difficult to manage acceptable performance when
working with large shapefiles, where large means >500MB, >3 million
features.  We've been splitting these both by feature type (pulling the
features we display at wider zooms into separate files) and by geography
(tiling).  It's tedious, time-consuming, and performance still isn't
what we'd wish.

The docs for PostGIS say that we can expect access times to be about 10%
greater than working with shapefiles, due to the overhead of
establishing a database, etc.

Is this constant?

What I'd like to be true is that PostGIS would offer indexing
possibilities that would allow for faster access to subsets of large
sets of geographic data than we're getting with shapefiles.

But what I'd like to be true isn't always the case.

Can I accomplish the sort of speedups I'm getting by splitting up
shapefiles, within PostGIS, without the expense of splitting up
shapefiles?

Can I do better?

Thanks.