what are the ways to avoid --- "ERROR: EXECUTE of SELECT ... INTO is not implemented yet"

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On Fri, May 30, 2008 at 09:57:49PM +0530, Shantanu wrote:

Hello experts,

I am facing this error.

mydb=> select version();
version

--------------------------------------------------------------------------------

PostgreSQL 8.1.9

(1 row)

mydb=> \i /tmp/test.sql
CREATE FUNCTION
mydb=> select sp_test();
ERROR: EXECUTE of SELECT ... INTO is not implemented yet
CONTEXT: PL/pgSQL function "sp_test" line 4 at execute statement

mydb=>
[1]+ Stopped su - dbu
mymachine<root># cat /tmp/test.sql
create or replace function sp_test() RETURNS void as $$
declare
l_var timestamp;
begin
execute 'SELECT NOW() INTO l_var';

^^^^^^^^^^^^^^^^^^

Why do you need execute '...' at all? Why not directly do instead

SELECT NOW() into l_var;

What is your "real" use case?

Note that if you really need the dynamic command, you might put its
result int a variable, like so:

EXECUTE 'SELECT NOW()' INTO l_var;

...but if we don't know what you are trying to achieve, it's difficult
to provide meaningful recommendations.

Regards
- -- tomás
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Shantanu wrote:

ERROR: EXECUTE of SELECT ... INTO is not implemented yet

PostgreSQL 8.3 includes support for EXECUTE ... INTO, so you may want to
look at an upgrade.

Personally I wouldn't call this a bug at all. It's just that PostgreSQL
knew how to parse that query before the support for actually executing
it was written.

--
Craig Ringer

Here is my real use case

1) We have nornal SELECT ...INTO calls in the procedure calls
2) However we landed ourselves with the following problem
http://www.postgresql.org/docs/faqs.FAQ.html#item4.19

<snip>
4.19) Why do I get "relation with OID ##### does not exist" errors when
accessing temporary tables in PL/PgSQL functions?

In PostgreSQL versions < 8.3, PL/PgSQL caches function scripts, and an
unfortunate side effect is that if a PL/PgSQL function accesses a temporary
table, and that table is later dropped and recreated, and the function
called again, the function will fail because the cached function contents
still point to the old temporary table. The solution is to use EXECUTE for
temporary table access in PL/PgSQL. This will cause the query to be reparsed
every time.

This problem does not occur in PostgreSQL 8.3 and later.
</snip>

3) So the solution we are trying to implement is the EXECUTE command one.

This is causing the SELECT ...INTO problem

Upgrade is not an option :(

Currently the only available solution is
Use a temporary table where we write the local variable and make it read
from the table .

Any alternatives ?

~
Shantanu

On Sat, May 31, 2008 at 8:38 AM, <tomas@tuxteam.de> wrote:

Here is my real use case

1) We have nornal SELECT ...INTO calls in the procedure calls
2) However we landed ourselves with the following problem
http://www.postgresql.org/docs/faqs.FAQ.html#item4.19

<snip>
4.19) Why do I get "relation with OID ##### does not exist" errors when
accessing temporary tables in PL/PgSQL functions?

In PostgreSQL versions < 8.3, PL/PgSQL caches function scripts, and an
unfortunate side effect is that if a PL/PgSQL function accesses a temporary
table, and that table is later dropped and recreated, and the function
called again, the function will fail because the cached function contents
still point to the old temporary table. The solution is to use EXECUTE for
temporary table access in PL/PgSQL. This will cause the query to be reparsed
every time.

This problem does not occur in PostgreSQL 8.3 and later.
</snip>

3) So the solution we are trying to implement is the EXECUTE command one.

This is causing the SELECT ...INTO problem

Upgrade is not an option :(

Currently the only available solution is
Use a temporary table where we write the local variable and make it read
from the table .

Any alternatives ?

~
Shantanu

On Sat, May 31, 2008 at 10:13 AM, Craig Ringer <craig@postnewspapers.com.au>
wrote:

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On Sat, May 31, 2008 at 10:51:35PM +0530, Shantanu wrote:

Here is my real use case

1) We have nornal SELECT ...INTO calls in the procedure calls
2) However we landed ourselves with the following problem
http://www.postgresql.org/docs/faqs.FAQ.html#item4.19

[...]

Any alternatives ?

Well -- according to the 8.1 docs (I don't have an 8.1 around at the
moment, sorry), one of my proposals should work:

On Sat, May 31, 2008 at 8:38 AM, <tomas@tuxteam.de> wrote:

[...]

Note that if you really need the dynamic command, you might put its
result int a variable, like so:

EXECUTE 'SELECT NOW()' INTO l_var;

[...]

(see <http://www.postgresql.org/docs/8.1/static/plpgsql-statements.html#PLPGSQL-STATEMENTS-EXECUTING-DYN&gt;).

Did you try that? Did it work?

Regards
- -- tomás
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