Re: More issues with expressions always false (no patch)

On 12/20/19 1:01 AM, Ranier Vilela wrote:> First case:
> src \ backend \ executor \ nodeSubplan.c (line 507)
>
> if (node-> hashtable)
>
> node-> hastable is assigned with NULL at line 498, so the test will
> always fail.
>
> Second case:
> Here the case is similar, but worse.
>
> src \ backend \ executor \ nodeSubplan.c (line 535)
> if (node-> hashnulls)
>   ResetTupleHashTable (node-> hashtable);

These two look like likely bugs. It looks like the code will always
create new hash tables despite commit
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=356687bd825e5ca7230d43c1bffe7a59ad2e77bd
intending to reset them if they already exist.

Additionally it looks like the code would reset the wrong hash table in
the second place if the bug was fixed.

I have attached a patch.

> Third case:
> \ src \ backend \ utils \ cache \ relcache.c (line 5190)
> if (relation-> rd_pubactions)
>
> It will never be executed, because if relation-> rd_pubactions is true,
> the function returns on line 5154.

I have not looked into this one in detail, but the free at line 5192
looks like potentially dead code.

Andreas