in a loop we'd like to obtain SQL (10046) traces separately for each district (1 district = 1 tracef

it is 11.2.0.3 on AIX.There is one long running session performing a loop of the same commands, like

begin
for district in 1..1000000 loop
the_"same"_commands_for_each_district;
end loop;
end;

we'd like to obtain SQL (10046) traces separately for each district (1 district = 1 tracefile) to be able to compare the values for a "good" and a "bad" district afterwards.

We are trying something like this

begin
for district in 1..1000000 loop
execute immediate alter session set tracefile_identifier = ...;
execute immediate alter session set events 10046 ...;
the_"same"_commands_for_each_district;
execute immediate alter session set events 10046 ... off;
end loop;
end;

The tracefiles are created correctly with various names as required.