ExecuteTruncate quirk: expects a unique list of relations

Hi,

Consider this simple case:

postgres=# TRUNCATE foo, foo;
ERROR: cannot TRUNCATE "foo" because it is being used by active queries in
this session

The above occurs because the ExecuteTruncate() function invokes
truncate_check_rel() in a loop. Since the same table name appears twice, the
rd_refcnt for table "foo" is bumped up to 2, causing the above failure.

We might want to add a step to ExecuteTruncate(), or whatever calls it, to
make the list unique.

Regards,
Nikhils
--
EnterpriseDB http://www.enterprisedb.com

Nikhils wrote:
> Hi,
>
> Consider this simple case:
>
> postgres=# TRUNCATE foo, foo;
> ERROR: cannot TRUNCATE "foo" because it is being used by active queries in
> this session
>
> The above occurs because the ExecuteTruncate() function invokes
> truncate_check_rel() in a loop. Since the same table name appears twice, the
> rd_refcnt for table "foo" is bumped up to 2, causing the above failure.
>
> We might want to add a step to ExecuteTruncate(), or whatever calls it, to
> make the list unique.

Fixed with attached, applied patch. I didn't see any other cases that
need fixing; LOCK foo, foo already works fine.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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