Re: row filtering for logical replication

On Tue, Feb 1, 2022 at 4:51 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> Review Comments:
> ===============
> 1.
> + else if (IsA(node, OpExpr))
> + {
> + /* OK, except user-defined operators are not allowed. */
> + if (((OpExpr *) node)->opno >= FirstNormalObjectId)
> + errdetail_msg = _("User-defined operators are not allowed.");
> + }
>
> Is it sufficient to check only the allowed operators for OpExpr? Don't
> we need to check opfuncid to ensure that the corresponding function is
> immutable? Also, what about opresulttype, opcollid, and inputcollid? I
> think we don't want to allow user-defined types or collations but as
> we are restricting the opexp to use a built-in operator, those should
> not be present in such an expression. If that is the case, then I
> think we can add a comment for the same.
>

Today, I was looking at a few other nodes supported by the patch and I
have similar questions for those as well. As an example, the patch
allows T_ScalarArrayOpExpr and the node is as follows:

typedef struct ScalarArrayOpExpr
{
Expr xpr;
Oid opno; /* PG_OPERATOR OID of the operator */
Oid opfuncid; /* PG_PROC OID of comparison function */
Oid hashfuncid; /* PG_PROC OID of hash func or InvalidOid */
Oid negfuncid; /* PG_PROC OID of negator of opfuncid function
* or InvalidOid. See above */
bool useOr; /* true for ANY, false for ALL */
Oid inputcollid; /* OID of collation that operator should use */
List *args; /* the scalar and array operands */
int location; /* token location, or -1 if unknown */
} ScalarArrayOpExpr;

Don't we need to check pg_proc OIDs like hashfuncid to ensure that it
is immutable like the patch is doing for FuncExpr? Similarly for
ArrayExpr node, don't we need to check the array_collid to see if it
contains user-defined collation? I think some of these might be okay
to permit but then it is better to have some comments to explain.

--
With Regards,
Amit Kapila.