Thread: scope quirk in copy in function
create or replace function archive_some_stuff() returns void as $$ declare cutoff timestamptz; begin cutoff := now() - '1 day'::interval; copy (select * from log where end_when < cutoff) to ... ... Gives me an error that there is column named cutoff. (Other uses of cutoff in queries not inside a copy, iow the delete fromcommands, work.) Is there any alternative to just duplicating the now() expression inside every copy? -- Scott Ribe scott_ribe@elevated-dev.com http://www.elevated-dev.com/ https://www.linkedin.com/in/scottribe/ (303) 722-0567 voice
On 03/23/2015 06:59 AM, Scott Ribe wrote: > create or replace function archive_some_stuff() returns void as $$ > 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 deletefrom 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
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