finding queries doing sequential search

Hi,

i have a very big table (PostGIS OpenStreetMap data, but that does not mapper) with about 380 million records and a size of 275 GB + Indices. Permanently updated and growing.

Of course i enabled autovacuum.

The log shows me 8.2 Mio index scans (iscan), which is fine,  and right now 424 sequential scans (sscan) for planet_osm_polygon. see attached image.

I want to locate the query doing this stuff but EXPLAIN won't help because most querys are dynamicly created.

Is there a way/trick do this?

Regards
walter