...as opposed to keeping the rasters as locally stored GEOTIFFs?

I have a large project that will require making available approximetely 50,000, 10mb GEOTIFFs as WMS to an OpenLayers based web map. Only 1 WMS will be displayed at any given time so performance is a non-issue. Considering MapServer and GeoServer for this application.

I would like to know what are the advantages and disadvantages of storing this type of data. Will updating a PostGIS database when the raster data changes be more difficult, rather than replacing a single (or series of) raster files. WMS load times drastically improved with PostGIS?

2 Answers 2


If all you're doing is passing rasters to end users with WMS, there is no reason to use PostGIS raster. If you need to do analysis (and more than a simple summary stats), then you may want to consider loading the rasters into PostGIS. Currently, in-db rasters are faster than out-db.

  • Can you expand.on in-db and out-db, what they mean and why one is slower then the other. Commented Aug 28, 2012 at 13:11
  • 2
    in-db is where the source raster (tile) is stored in PostgreSQL. out-db only stores metadata describing the source raster in PostgreSQL and any functions in PostGIS will call the source raster files as needed. In my testing, out-db is slower than in-db. As to why out-db is slower, my suspicion is that PostgreSQL is able to cache the in-db data in its shared buffers while out-db requires calling the source file every time.
    – dustymugs
    Commented Aug 31, 2012 at 17:12

From general reading of MapServer and GeoServer comparisons online, I found the consensus to be that MapServer was quicker for serving rasters. I have a setup similar to what you describe for providing rasters (rasters in a folder) as a WMS using MapServer and it is extremely fast.

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