[postgis-users] ST_Difference and many polygons?

[charlie]

Hi.  I am a new PostGIS user and have successfully installed and been using PostGIS for about a month now, but have hit a roadblock on a particular issue.  I have imported 2 shapefiles with approximately 70k polygons and 50k polygons respectively, which covers the identical shoreline 3 decades apart.  I am looking to parse out the changes in the 2 shorelines databases to illustrate the changes over time and save it separately in PostGIS.  As it stands now, I have fixated upon ST_Difference as the likely way to handle this, but all the examples I have found only show how to use ST_Difference on 2 polygons, rather than many thousands.  As a new  PostGIS user  is this the the best way to handle this? Can anyone share any examples?  Thanks in advance for your advice!
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