disable warning from `drop table if exists` When I DROP a table with the IF EXISTS clause (in PostgreSQL 11.x), it issues a warning as follows:

=&gt; DROP TABLE IF EXISTS tt;

NOTICE:  table "tt" does not exist, skipping


Sometimes, I do expect that certain tables to not exist, and don't want to see many warnings like these in the output of a batch processing function/script.

Is there a way to disable this type of warning altogether?
The "warning" is in fact a "notice". You can disable the display of those notices trough the property client_min_messages  which controls the minimum level of messages returned to the client. 

To only display warnings, but not notices use:

set client_min_messages = warning;


Note that this will disable all notices, including those sent through raise notice from e.g. a PL/pgSQL function.