ERROR: out of shared memory - But the table is empty

Hi there,

not being an expert for Postgres…. I have a Postgis table with the countries of the world. Now, I would like to drop
it.I got the error message: 

     ERROR:  out of shared memory
     HINT:  You might need to increase max_locks_per_transaction.

and thought that it would be easier to drop first all rows, and then drop the empty table.

But it seems that it has a problem with dropping the index:

      DROP INDEX gis.countries_uid;

actually generates that error message.

So, do I need to dig now into the postgres config file? It seems strange to me that Postgres has a problem deleting an
emptytable, though. 

Thanks for any hints.