Обсуждение: How to Declare Functions Containing OUT PArameters?
I'm having some difficulty getting plpgsql to recognize a function with a couple of OUT parameters. I'm either declaring the function incorrectly, making the call to it in the wrong way or my program is simply possessed by evil spirits. I'm using Postgres 8.1.5. What appears to be happening is that it's declaring the function as if it returned a record and had only two parameters, but I'm trying to call it with four parameters, with two of them being OUT parameters. So the compiler sees two different versions of the function and refused to do anything more. The example below shows the problem, but it's just something to exercise the function calls and generate the error. Can anyone spot the screw-up in this little example? (the error message is listed below in the block comment) TIA, -Bill Thoen CREATE OR REPLACE FUNCTION fishy( s1 text, s2 text, OUT n integer, OUT f real ) AS $$ DECLARE c integer; BEGIN c := length( s1 ); n := length( s1 || s2 ); f := c::real / n::real; END; $$ LANGUAGE plpgsql; CREATE OR REPLACE FUNCTION main() RETURNS VOID AS $$ DECLARE str1 text; str2 text; num integer := 0; fnum real := 0.0; BEGIN str1 := 'One fish, two fish'; str2 := 'Shark fish, No fish'; SELECT fishy( str1, str2, num, fnum) ; RAISE NOTICE 'fishy() analysis: % %', num, fnum; END; $$ LANGUAGE plpgsql; SELECT main(); /* ERROR MESSAGE psql:ex_out_fail.sql:28: ERROR: function fishy(text, text, integer, real) does not exist HINT: No function matches the given name and argument types. You may need to add explicit type casts. CONTEXT: SQL statement "SELECT fishy( $1 , $2 , $3 , $4 )" PL/pgSQL function "main" line 9 at SQL statement And when I run \df from the pgsql command line, it shows up like this: | fishy | record | text, text */
Hello PostgreSQL use OUT params very untypically. You can't to directly to join OUT parameter with some variable. It isn't possible. please, try CREATE OR REPLACE FUNCTION foo(a int, b int, OUT c int, OUT d int) RETURNS record AS $$ BEGIN c := a + 1; d := b + 1; RETURN; END; $$ LANGUAGE plpgsql strict immutable; CREATE OR REPLACE FUNCTION use_foo() RETURNS void AS $$ DECLARE r record AS $$ BEGIN r := foo(10,20); RAISE NOTICE '% %', r.c, r.d; END; $$ LANGUAGE plpgsql immutable; SELECT use_foo(); Regard Pavel Stehule 2010/7/14 Bill Thoen <bthoen@gisnet.com>: > I'm having some difficulty getting plpgsql to recognize a function with a > couple of OUT parameters. I'm either declaring the function incorrectly, > making the call to it in the wrong way or my program is simply possessed by > evil spirits. I'm using Postgres 8.1.5. > What appears to be happening is that it's declaring the function as if it > returned a record and had only two parameters, but I'm trying to call it > with four parameters, with two of them being OUT parameters. So the compiler > sees two different versions of the function and refused to do anything more. > The example below shows the problem, but it's just something to exercise the > function calls and generate the error. Can anyone spot the screw-up in this > little example? (the error message is listed below in the block comment) > TIA, > -Bill Thoen > > CREATE OR REPLACE FUNCTION fishy( s1 text, s2 text, OUT n integer, OUT f > real ) AS $$ > DECLARE > c integer; > BEGIN > c := length( s1 ); > n := length( s1 || s2 ); > f := c::real / n::real; > END; > $$ LANGUAGE plpgsql; > > CREATE OR REPLACE FUNCTION main() RETURNS VOID AS $$ > DECLARE > str1 text; > str2 text; > num integer := 0; > fnum real := 0.0; > BEGIN > str1 := 'One fish, two fish'; > str2 := 'Shark fish, No fish'; > SELECT fishy( str1, str2, num, fnum) ; > > RAISE NOTICE 'fishy() analysis: % %', num, fnum; > END; > $$ LANGUAGE plpgsql; > > SELECT main(); > > /* ERROR MESSAGE > > psql:ex_out_fail.sql:28: ERROR: function fishy(text, text, integer, real) > does not exist > HINT: No function matches the given name and argument types. You may need > to add explicit type casts. > CONTEXT: SQL statement "SELECT fishy( $1 , $2 , $3 , $4 )" > PL/pgSQL function "main" line 9 at SQL statement > > And when I run \df from the pgsql command line, it shows up like this: > | fishy | record | text, text > > */ > > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general >
On Wed, 2010-07-14 at 12:21 -0600, Bill Thoen wrote: > I'm having some difficulty getting plpgsql to recognize a function with > a couple of OUT parameters. I'm either declaring the function > incorrectly, making the call to it in the wrong way or my program is > simply possessed by evil spirits. I'm using Postgres 8.1.5. First, 8.1.x is EOL as of November. You need to upgrade. > CREATE OR REPLACE FUNCTION main() RETURNS VOID AS $$ > DECLARE > str1 text; > str2 text; > num integer := 0; > fnum real := 0.0; > BEGIN > str1 := 'One fish, two fish'; > str2 := 'Shark fish, No fish'; > SELECT fishy( str1, str2, num, fnum) ; > /* ERROR MESSAGE > > psql:ex_out_fail.sql:28: ERROR: function fishy(text, text, integer, > real) does not exist > HINT: No function matches the given name and argument types. You may > need to add explicit type casts. > CONTEXT: SQL statement "SELECT fishy( $1 , $2 , $3 , $4 )" > PL/pgSQL function "main" line 9 at SQL statement > You are passing four IN paramaters. The out paramaters are used in return are they not? Joshua D. Drake -- PostgreSQL.org Major Contributor Command Prompt, Inc: http://www.commandprompt.com/ - 509.416.6579 Consulting, Training, Support, Custom Development, Engineering
"Joshua D. Drake" <jd@commandprompt.com> writes:
> On Wed, 2010-07-14 at 12:21 -0600, Bill Thoen wrote:
>> I'm having some difficulty getting plpgsql to recognize a function with
>> a couple of OUT parameters.
>> psql:ex_out_fail.sql:28: ERROR: function fishy(text, text, integer,
>> real) does not exist
> You are passing four IN paramaters. The out paramaters are used in
> return are they not?
You'd need to do something like
SELECT * INTO num, fnum FROM fishy(str1, str2) ;
OUT parameters in PG are just syntactic sugar for defining a
record-returning function. The call syntax still works as if you'd
written CREATE FUNCTION foo (IN-parameters-only) RETURNS some-record-type.
regards, tom lane
Thanks guys. I think I see now. I was thinking it was a more transparent pass-by-value / pass-by-reference thing. Anyway I solved my problem by going back into my comfort zone and explicitly return a record and I'm not using OUT parameters. They're aren't what I thought they were and I'm working on a tight schedule, so I don't have much toim m eto explre. The compiler seems happier without them, and when it's happy, I'm happy. Tom Lane wrote: > "Joshua D. Drake" <jd@commandprompt.com> writes: > >> On Wed, 2010-07-14 at 12:21 -0600, Bill Thoen wrote: >> >>> I'm having some difficulty getting plpgsql to recognize a function with >>> a couple of OUT parameters. >>> > > >>> psql:ex_out_fail.sql:28: ERROR: function fishy(text, text, integer, >>> real) does not exist >>> > > >> You are passing four IN paramaters. The out paramaters are used in >> return are they not? >> > > You'd need to do something like > > SELECT * INTO num, fnum FROM fishy(str1, str2) ; > > OUT parameters in PG are just syntactic sugar for defining a > record-returning function. The call syntax still works as if you'd > written CREATE FUNCTION foo (IN-parameters-only) RETURNS some-record-type. > > regards, tom lane > >
On Wed, 2010-07-14 at 12:21 -0600, Bill Thoen wrote: > I'm having some difficulty getting plpgsql to recognize a function with > a couple of OUT parameters. I'm either declaring the function > incorrectly, making the call to it in the wrong way or my program is > simply possessed by evil spirits. I'm using Postgres 8.1.5. First, 8.1.x is EOL as of November. You need to upgrade. > CREATE OR REPLACE FUNCTION main() RETURNS VOID AS $$ > DECLARE > str1 text; > str2 text; > num integer := 0; > fnum real := 0.0; > BEGIN > str1 := 'One fish, two fish'; > str2 := 'Shark fish, No fish'; > SELECT fishy( str1, str2, num, fnum) ; > /* ERROR MESSAGE > > psql:ex_out_fail.sql:28: ERROR: function fishy(text, text, integer, > real) does not exist > HINT: No function matches the given name and argument types. You may > need to add explicit type casts. > CONTEXT: SQL statement "SELECT fishy( $1 , $2 , $3 , $4 )" > PL/pgSQL function "main" line 9 at SQL statement > You are passing four IN paramaters. The out paramaters are used in return are they not? Joshua D. Drake -- PostgreSQL.org Major Contributor Command Prompt, Inc: http://www.commandprompt.com/ - 509.416.6579 Consulting, Training, Support, Custom Development, Engineering