Re: Fix foreign key constraint check for partitioned tables

On Sat, 23 Mar 2019 at 12:01, Hadi Moshayedi <hadi(at)moshayedi(dot)net> wrote:
> Yesterday while doing some tests, I noticed that the following doesn't work properly:
>
> create role test_role with login;
> create table ref(a int primary key);
> grant references on ref to test_role;
> set role test_role;
> create table t1(a int, b int) partition by list (a);
> alter table t1 add constraint t1_b_key foreign key (b) references ref(a);
>
> In postgres 11.2, this results in the following error:
>
> ERROR: could not open file "base/12537/16390": No such file or directory
>
> and in the master branch it simply crashes.
>
> It seems that validateForeignKeyConstraint() in tablecmds.c cannot use RI_Initial_Check() to check the foreign key constraint, so it tries to open the relation and scan it and verify each row by a call to RI_FKey_check_ins(). Opening and scanning the relation fails, because it is a partitioned table and has no storage.
>
> The attached patch fixes the problem by skipping foreign key constraint check for relations with no storage. In partitioned table case, it will be verified by scanning the partitions, so we are safe to skip the parent table.

Hi Hadi,

I reproduced the problem and tested your fix. It looks simple and
correct to me.

I was a bit curious about the need for "set role" in the reproduction,
but I see that it's because RI_Initial_Check does some checks to see
if a simple SELECT can be used, and one of the checks is for basic
table permissions.

I wonder if the macro RELKIND_HAS_STORAGE should be used instead of
checking for each relkind? This would apply to the check on line 4405
too.

Edmund