Обсуждение: Question about "Unrecognized SPI code" ...

I just found an interesting issue in recent PostgreSQL releases:

CREATE VIEW view_nonsense AS SELECT 1 AS a, 2 AS b;

CREATE RULE myrule AS ON INSERT TO view_nonsense        DO INSTEAD NOTHING;

CREATE OR REPLACE FUNCTION debug() RETURNS boolean AS '        DECLARE
        BEGIN                INSERT INTO view_nonsense VALUES (10, 20);                RETURN true;        END;
' LANGUAGE 'plpgsql';

SELECT debug();

The INSERT statement is not doing something useful here


[hs@athlon tmp]$ psql test < view.sql
CREATE VIEW
CREATE RULE
CREATE FUNCTION
ERROR:  SPI_execute_plan failed executing query "INSERT INTO 
view_nonsense VALUES (10, 20)": Unrecognized SPI code 0
CONTEXT:  PL/pgSQL function "debug" line 4 at SQL statement


SPI_result_code_string(int code) and PL/pgSQL don't seem to be aware of 
DO NOTHING rules.
Is it desired behaviour?
Best regards,
    Hans

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Hans-Jürgen Schönig <postgres@cybertec.at> writes:
> ERROR:  SPI_execute_plan failed executing query "INSERT INTO 
> view_nonsense VALUES (10, 20)": Unrecognized SPI code 0
> CONTEXT:  PL/pgSQL function "debug" line 4 at SQL statement

> SPI_result_code_string(int code) and PL/pgSQL don't seem to be aware of 
> DO NOTHING rules.

Hmm.  What's happening is that _SPI_execute_plan() initializes its local
result variable to 0, and then that ends up getting returned because the
execute-one-query loop executes zero times.  Since 0 isn't a defined SPI
result code, this seems bad.

The question is what to return instead.  Of the currently defined SPI
result codes, SPI_OK_UTILITY seems the closest, but it implies that
something happened when nothing did.  Is it worth inventing a new
result code SPI_OK_NOTHING (or similar) to describe this case?  That
would possibly imply changing a lot of SPI-using code to handle the
new result alternative.
        regards, tom lane