PostgreSQL data wrapper for template tables - any DML and SELECT operations are disallowed
plpgsql_check cannot verify queries over temporary tables that are created in plpgsql's function runtime. For this use case it is necessary to create a fake temp table or disable plpgsql_check for this function.
In reality temp tables are stored in own (per user) schema with higher priority than persistent tables. So you can do (with following trick safetly):
CREATE OR REPLACE FUNCTION public.disable_dml()
RETURNS trigger
LANGUAGE plpgsql AS $function$
BEGIN
RAISE EXCEPTION SQLSTATE '42P01'
USING message = format('this instance of %I table doesn''t allow any DML operation', TG_TABLE_NAME),
hint = format('you should to run "CREATE TEMP TABLE %1$I(LIKE %1$I INCLUDING ALL);" statement',
TG_TABLE_NAME);
RETURN NULL;
END;
$function$;
CREATE TABLE foo(a int, b int); -- doesn't hold data ever
CREATE TRIGGER foo_disable_dml
BEFORE INSERT OR UPDATE OR DELETE ON foo
EXECUTE PROCEDURE disable_dml();
postgres=# INSERT INTO foo VALUES(10,20);
ERROR: this instance of foo table doesn't allow any DML operation
HINT: you should to run "CREATE TEMP TABLE foo(LIKE foo INCLUDING ALL);" statement
postgres=#
CREATE TABLE
postgres=# INSERT INTO foo VALUES(10,20);
INSERT 0 1
This trick emulates GLOBAL TEMP tables partially and it allows a statical validation. Other possibility is using a [template foreign data wrapper] (https://github.com/okbob/template_fdw)
The usage of template_fdw is safer, because any regress tests fails immediately when any foreign table based on tempate_fdw is used.
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