Plan cache and name space behavior in 9.2 - Mailing list pgsql-hackers

From Hitoshi Harada
Subject Plan cache and name space behavior in 9.2
Date
Msg-id CAP7Qgm=z9hsd9kQdFR=LuC-TwBSXJRZsy+EWE5r_0Zn-c2NdYg@mail.gmail.com
Whole thread Raw
Responses Re: Plan cache and name space behavior in 9.2
List pgsql-hackers
I came across a new behavior in 9.2 with nested plpgsql functions and
temporary table.

create or replace function chck(tname text) returns void as $$
declare cnt int;
begin select count(*) from pg_attribute where attrelid = tname::regclass::oid   into cnt;
end;
$$ language plpgsql;

create or replace function train(tname text) returns text as $$
declare
begin perform chck(tname); return 'OK';
end;
$$ language plpgsql;

create or replace function test(tname text) returns text as $$
declare result text;
begin result = train(tname); return result;
end;
$$ language plpgsql;

drop table if exists tbl;
create table tbl(a int);
select test('tbl'); -- call 1
drop table if exists tbl;

create temp table tbl(a int);
select test('tbl'); -- call 2
drop table tbl;

I expected success in tname::regclass in the function chck(), but it
actually fails for your first run in the session.  The second run of
this script will succeed.  I assume it's the cause is the new plan
cache behavior.  On the first run of the script, the temporary
namespace was not created when the chck() is called at call 1 , and it
saves namespace, then it searches the old saved namespace for 'tbl' at
call 2, fails to find 'tbl'.  Removing the call 1 call it runs
successfully.  The second  run of this script in the same session
succeeds because the temporary namespace has been created in the first
run.  I confirmed it runs fine in 9.1  Is this a bug in 9.2 or an
expected behavior in the new plan cache?

Thanks,
-- 
Hitoshi Harada



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