[postgis-users] PostGIS Raster ST_Value ST_SetValue performance

Miguel-Angel Manso-Callejo (UPM) m.manso at upm.es
Fri Jun 28 02:02:48 PDT 2013

Good morning,

It's my first comment to the email-list.

I'm developing a PLSQL-procedure that generate a raster band counting 
points of a geometry table/layer that are included in a cell. This can 
be seen as a simple clustering algorithm.

To do it, i'm using a cursor and determining the row and column of the 
pixel do an increment operation over pixel value. This is a ST_Value + 
ST_SetValue operation foreach point.
This is very slow.

In Oracle, this is slow too, but i can take an alternative way. Using a 
Array with binary index simulate the image, and latter when all the 
point has been "mapped" over the matrix transform this to a cellblob and 
later insert it on table that store image.

Have any one in the list any similar experience?
Can any give me a new orientation?

Best regards,
Miguel A. Manso

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