Changelog category:

• Improvement

Changelog entry:
This PR changes restrictive row policies a bit to make them an easier alternative to permissive policies in easy cases.
If for a particular table only restrictive policies exist (without permissive policies) users will be able to see some rows.
Also SHOW CREATE ROW POLICY will always show AS permissive or AS restrictive in row policy's definition.

For example, if we have three users John, Lucy, and Alex and following policies:

CREATE POLICY r1 ON mydb.mytable FOR SELECT USING a=1 AS restrictive TO John;
CREATE POLICY r2 ON mydb.mytable FOR SELECT USING a=2 AS restrictive TO Lucy;

then with the changes of this PR John will see rows with a=1, Lucy will see rows with a=2 and Alex will see any rows.

Before this PR permissive policies were always required to see anything, so in the above example anybody would see nothing.