Recently at work I was asked to look into some issues about performance (of course blaming it on the database) when used with ArcGIS. I thought it would be interesting to share my findings, especially showing the huge difference in performance. Well done QGIS team:
This is not an Oracle issue, or a network issue. For example, doing a select all on RSP_12_SLOPE returns 10 rows. Yes those geometry collections on each row are huge, and the total volume of data is about 37 MB, but the query and transfer time from the production DB to my slow laptop is usually less than one second (longest was 4 seconds). With ArcGIS this query time averages about 5 seconds. So that data is on the client computer reasonably quickly.
This is obviously an ESRI code issue. I won't sugar coat this - their render code performance stinks in ArcGIS classic, and appears to be even worse in the new Pro version. Based on my observations I have to assume their on-the-fly conversion routines from the Oracle SDO_GEOMETRY to their internal render format are horribly inefficient. I see this not only with these large collections, but also with simple points where there are thousands of points being rendered on the screen.
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