I wonder if it is getting slower because of the date query that you're
doing? You may try indexing raster_date field. Putting an index on that
might slow down inserts but it would improve updates. I would certainly
expect that your updates would get slower overtime for a non-indexed date
match.
lists.osgeo.org
> Subject: [postgis-users] Raster time-series data
>
> I'm trying to import (what I think of as) large timeseries of gridded data in
> postgis 2.0 (on PostgreSQL. The data comes as HDF-EOS files (basically HDF4).
> Each file has the whole grid, which is 22680 points, and 24
