postgresql embedded function return - postgresql

Question

I'm trying to call a function from a trigger function and don't understand what control structure to use. Here's the situation:
I have 3 tables (table1, table2, table3) and two functions (Fct1 and Fct2).
Fct1 is a trigger function triggered after an insert in table1 and which makes insert in table2:
CREATE OR REPLACE FUNCTION Fct1()
RETURNS TRIGGER AS
$BODY$
BEGIN
TRUNCATE "table2";
INSERT INTO "table2"
SELECT ... FROM "table1";
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
The trigger is:
CREATE TRIGGER trig_fct1
AFTER INSERT
ON table1
FOR EACH ROW
WHEN ((pg_trigger_depth() < 1))
EXECUTE PROCEDURE Fct1();
If I do after that a SELECT "Fct2"(); everything works fine, but if I add in Fct1 a PERFORM "Fct2"(); , like this:
CREATE OR REPLACE FUNCTION Fct1()
RETURNS TRIGGER AS
$BODY$
BEGIN
TRUNCATE "table2";
INSERT INTO "table2"
SELECT ... FROM "table1";
TRUNCATE "table3";
PERFORM "Fct2"(); -- will insert into table3
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
It takes much more time to run (I never waited for the end, it's too long).
Fct2 looks like this
CREATE OR REPLACE FUNCTION "Fct2"()
RETURNS void AS
$BODY$
BEGIN
INSERT INTO "table3" ...;
RETURN;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
So, there is something I don't understand and I think it is related to these 'RETURNs' which are not clear to me. I have tried different 'solutions' but I always got errors mentioning some 'return' mismatches. Any suggestions ?
I'm using PostgreSQL 9.6

Answer 1

To capture long running SQL statements from functions in the log, you can use auto_explain with auto_explain.log_nested_statements set to on. But if the query doesn't even finish, that won't help a lot.
My bet is that you are blocked by a database lock. Set log_lock_waits to on and see if something is reported in the log. You should also query pg_locks to see if there are locks requested but not granted.