Re: procedures and plpgsql PERFORM - Mailing list pgsql-hackers

From Pavel Stehule
Subject Re: procedures and plpgsql PERFORM
Date
Msg-id CAFj8pRBz8XAwaT0a-hyRDtfzQn0Mfmh3z7kww-iYWdMoUTPFug@mail.gmail.com
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In response to procedures and plpgsql PERFORM  (Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>)
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2017-12-14 8:21 GMT+01:00 Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>:
Hi,
We allow a function to be invoked as part of PERFORM statement in plpgsql
do $$
begin perform pg_relation_size('t1'); end; $$ language plpgsql;
DO

But we do not allow a procedure to be invoked this way
 create procedure dummy_proc(a int) as $$
begin null; end;
$$ language plpgsql;
CREATE PROCEDURE

do $$
begin perform dummy_proc(1); end; $$ language plpgsql;
ERROR:  dummy_proc(integer) is a procedure
LINE 1: SELECT dummy_proc(1)
               ^
HINT:  To call a procedure, use CALL.
QUERY:  SELECT dummy_proc(1)
CONTEXT:  PL/pgSQL function inline_code_block line 2 at PERFORM

The documentation of PERFORM [1] says
"For any SQL command that does not return rows, for example INSERT
without a RETURNING clause, you can execute the command within a
PL/pgSQL function just by writing the command."

Procedures fit that category and like functions, I think, we should
allow them be invoked directly without any quoting and CALL
decoration.

Why? The CALL is four chars more. It is keyword, and it reduce parser complexity - we should not to different between routine name and variable name.

So -1 from my for this proposal.

Regards

Pavel

[1] https://www.postgresql.org/docs/devel/static/plpgsql-statements.html#PLPGSQL-STATEMENTS-SQL-NORESULT
--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company


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