[postgis-users] advice for quicker display?

[Stephen V. Mather]

To expand on that, the basic understanding is that file level access to data
(e.g. shapefile) will always be faster for the entire dataset (all things
being equal) because of the management overhead of the database, but for
accessing a subset of features of the dataset (often the typical use case),
the database is faster if it has indices on the appropriate columns (the
geometry being the more important one).  Even if you are accessing all of
the records in the database at once as a common case, you probably don't
need every node in the polygons/polylines, and might create a view or column
that pre-generalizes those data before delivering them.

Best,
Steve

Stephen Mather
Geographic Information Systems (GIS) Manager
(216) 635-3243
svm at clevelandmetroparks.com
clevelandmetroparks.com




-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Stephen
Woodbridge
Sent: Tuesday, February 14, 2012 2:15 PM
To: postgis-users at postgis.refractions.net
Subject: Re: [postgis-users] advice for quicker display?

On 2/14/2012 1:57 PM, Bistrais, Bob wrote:
> As some of you already know, I'm a newbie to PostGIS and have just
> barely got a test PostGIS database up and running. So, my latest
> question is in regards to draw times. I created a statewide parcel layer
> from a shapefile. At statewide scale, when the application loads, the
> parcel data draws far slower than the original shapefile did. How can I
> tune this so that draw times are better?

If you are drawing all the data, it will always be slower than 
shapefiles. The trick is to not draw more than is reasonable at a given 
scale. So the answer is don't try to draw all the parcels for the whole 
state. As you zoom in and need to only draw a subset of the parcels, you 
will start to get speed advantages by using the spatial (GIST) indexes 
in postgis.

create index mytable_the_geom_gidx on mytable using gist (the_geom);

-Steve W
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