Re: plpgsql plugin - stmt_beg/end is not called for top level block of statements

pá 28. 12. 2018 v 3:26 odesílatel Michael Paquier <michael(at)paquier(dot)xyz>
napsal:

> On Wed, Dec 26, 2018 at 07:02:04AM +0100, Pavel Stehule wrote:
> > is called two times, what is not expected, if you don't know some about
> > this inconsistency.
> >
> > So it is reason, why I don't think so current behave is correct. On
> second
> > hand, the impact is very small - only few extensions uses plpgsql plugin
> > API, and workaround is not hard. So I can live with current state if
> nobody
> > see this issue (sure - it is minor issue).
>
> Hm. Using the following functions based on the code of above, I can
> see the following numbers if I place some trackers (elog(WARNING)
> entries) at the beginning of each callback part of plpgsql_check.c to
> measure how many times a callback is done:
> CREATE OR REPLACE FUNCTION public.f2()
> RETURNS void
> LANGUAGE plpgsql
> AS $$
> DECLARE x int;
> BEGIN
> x := 2;
> RETURN;
> END;
> $$;
> CREATE OR REPLACE FUNCTION public.f3()
> RETURNS void
> LANGUAGE plpgsql
> AS $$
> DECLARE x int;
> BEGIN
> BEGIN
> x := 3;
> RETURN;
> END;
> END
> $$;
>
> On HEAD, for plpgsql_check_function_tb('f2()'):
> - stmt_beg is called 4 times.
> - stmt_end is called 3 times.
> - func_setup is called 2 times.
> - func_beg is called 2 times.
> - func_end is called 2 times.
> For plpgsql_check_function_tb('f3()'):
> - stmt_beg is called 3 times.
> - stmt_end is called 3 times.
> - func_setup is called 1 time.
> - func_beg is called 1 time.
> - func_end is called 2 times.
>
> So based on the previous example f2 gets over f3 one extra stmt_beg,
> one extra func_beg and one extra func_setup.
>
> With patched HEAD, I got for f2:
> - stmt_beg is called 6 times.
> - stmt_end is called 5 times.
> - func_setup is called 2 times.
> - func_beg is called 2 times.
> - func_end is called 2 times.
> And for f3:
> - stmt_beg is called 6 times.
> - stmt_end is called 5 times.
> - func_setup is called 2 times.
> - func_beg is called 2 times.
> - func_end is called 2 times.
> --
> Michael
>

These numbers are little bit strange - maybe due using plpgsql_check. I
wrote simple extension (see attachment)

CREATE OR REPLACE FUNCTION public.f2()
RETURNS void
LANGUAGE plpgsql
1 AS $function$
2 DECLARE x int;
3 BEGIN
4 x := 2;
5 RETURN;
6 END;
7 $function$

CREATE OR REPLACE FUNCTION public.f3()
RETURNS void
LANGUAGE plpgsql
1 AS $function$
2 DECLARE x int;
3 BEGIN
4 BEGIN
5 x := 3;
6 RETURN;
7 END;
8 END
9 $function$

load 'simple';
select f2();

postgres=# select f2();
NOTICE: func setup: "f2()"
NOTICE: func beg: "f2()"
NOTICE: stmt beg - ln: 4
NOTICE: stmt end - ln: 4
NOTICE: stmt beg - ln: 5
NOTICE: stmt end - ln: 5
NOTICE: func end: "f2()"

NOTICE: func setup: "f3()"
NOTICE: func beg: "f3()"
NOTICE: stmt beg - ln: 4
NOTICE: stmt beg - ln: 5
NOTICE: stmt end - ln: 5
NOTICE: stmt beg - ln: 6
NOTICE: stmt end - ln: 6
NOTICE: stmt end - ln: 4
NOTICE: func end: "f3()"

patched

postgres=# select f2();
NOTICE: func setup: "f2()"
NOTICE: func beg: "f2()"
NOTICE: stmt beg - ln: 3
NOTICE: stmt beg - ln: 4
NOTICE: stmt end - ln: 4
NOTICE: stmt beg - ln: 5
NOTICE: stmt end - ln: 5
NOTICE: stmt end - ln: 3
NOTICE: func end: "f2()"

postgres=# select f3();
NOTICE: func setup: "f3()"
NOTICE: func beg: "f3()"
NOTICE: stmt beg - ln: 3
NOTICE: stmt beg - ln: 4
NOTICE: stmt beg - ln: 5
NOTICE: stmt end - ln: 5
NOTICE: stmt beg - ln: 6
NOTICE: stmt end - ln: 6
NOTICE: stmt end - ln: 4
NOTICE: stmt end - ln: 3
NOTICE: func end: "f3()"

There is only one difference - the plugin routine stmt_begin and stmt_end
is called for line 3. Nothing less, nothing more.

Internal evaluation of plpgsql code is same - the change is only for plugin
code - one more stmt_beg and stmt_end call - as expected and wanted.

Real impact - now, I have to push my code to func_beg, func_end, stmt_beg,
stmt_end. With patch I can push my code just to stmt_beg, stmt_end.

Regards

Pavel