scope quirk in copy in function

On 03/23/2015 06:59 AM, Scott Ribe wrote:

create or replace function archive_some_stuff() returns void as $$
declare cutoff timestamptz;
begin
cutoff := now() - '1 day'::interval;
copy (select * from log where end_when < cutoff) to ...
...

Gives me an error that there is column named cutoff. (Other uses of cutoff in queries not inside a copy, iow the delete from commands, work.)

Is there any alternative to just duplicating the now() expression inside every copy?

http://www.postgresql.org/docs/9.3/interactive/plpgsql-implementation.html#PLPGSQL-VAR-SUBST

"Variable substitution currently works only in SELECT, INSERT, UPDATE,
and DELETE commands, because the main SQL engine allows query parameters
only in these commands. To use a non-constant name or value in other
statement types (generically called utility statements), you must
construct the utility statement as a string and EXECUTE it."

--
Adrian Klaver
adrian.klaver@aklaver.com

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Adrian Klaver <adrian.klaver@aklaver.com> writes:

On 03/23/2015 06:59 AM, Scott Ribe wrote:

create or replace function archive_some_stuff() returns void as $$
declare cutoff timestamptz;
begin
cutoff := now() - '1 day'::interval;
copy (select * from log where end_when < cutoff) to ...

"Variable substitution currently works only in SELECT, INSERT, UPDATE,
and DELETE commands, because the main SQL engine allows query parameters
only in these commands. To use a non-constant name or value in other
statement types (generically called utility statements), you must
construct the utility statement as a string and EXECUTE it."

Yeah. It seems like SELECT-inside-COPY might be worth special casing
though. ISTM this is more or less analogous to the case of PREPARE or
DECLARE CURSOR, which are also utility commands that contain a regular DML
command. I'm pretty sure there is a hack in there that allows parameters
to be transmitted down through PREPARE or D.C. ...

regards, tom lane

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