Re: BUG #8198: ROW() literals not supported in an IN clause

On Wednesday, June 05, 2013 5:34 AM Rafał Rzepecki wrote:
> On Tue, Jun 4, 2013 at 12:35 PM, Amit Kapila <amit(dot)kapila(at)huawei(dot)com>
> wrote:
> > On Saturday, June 01, 2013 9:37 PM
> >
> >> Row type literals constructed with ROW() cause an error when used in
> >> an IN clause (string literals casted appropriately are allowed).
> This
> >> is especially problematic since many client libraries use these
> >> literals to pass values of row-type arguments, hence making it
> >> impossible to use them in IN-clause queries.
> >>
>
> If I'm right, the proper fix would be (patch 0001; caution, not
> tested):
>
> --- a/src/backend/parser/parse_expr.c
> +++ b/src/backend/parser/parse_expr.c
> @@ -1203,10 +1203,9 @@ transformAExprIn(ParseState *pstate, A_Expr *a)
> Node *rexpr = (Node *) lfirst(l);
> Node *cmp;
>
> - if (haveRowExpr)
> + if (haveRowExpr && IsA(lexpr, RowExpr))
> {
> - if (!IsA(lexpr, RowExpr) ||
> - !IsA(rexpr, RowExpr))
> + if (!IsA(rexpr, RowExpr))
> ereport(ERROR,
>
> (errcode(ERRCODE_SYNTAX_ERROR),
> errmsg("arguments of row IN must all
> be row expressions"),
>
>
> Since the restriction seems a rather arbitrary (at least I fail to see
> any reason for it), it can be removed altogether (patch 0002, not
> tested as well):
>
> --- a/src/backend/parser/parse_expr.c
> +++ b/src/backend/parser/parse_expr.c
> @@ -1203,20 +1203,12 @@ transformAExprIn(ParseState *pstate, A_Expr *a)
> Node *rexpr = (Node *) lfirst(l);
> Node *cmp;
>
> - if (haveRowExpr)
> - {
> - if (!IsA(lexpr, RowExpr) ||
> - !IsA(rexpr, RowExpr))
> - ereport(ERROR,
> -
> (errcode(ERRCODE_SYNTAX_ERROR),
> - errmsg("arguments of row IN must
> all be row expressions"),
> -
> parser_errposition(pstate, a->location)));
> + if (IsA(lexpr, RowExpr) && IsA(rexpr, RowExpr))
> cmp = make_row_comparison_op(pstate,
>
> a->name,
> (List *)
> copyObject(((RowExpr *) lexpr)->args),
>
> ((RowExpr *) rexpr)->args,
>
> a->location);
> - }
> else
> cmp = (Node *) make_op(pstate,
> a-
> >name,
>

I had tried, both your patches have passed all regression tests (tested on Windows). I feel fixing it in a way similar to your Patch-1 would be
more appropriate as with Patch-1 it can generate meaningful error message for some cases like below:

postgres=# select * from the_table where ROW('abc','def') in (row('foo','bar')::the_row,12);
ERROR: arguments of row IN must all be row expressions
LINE 1: select * from the_table where ROW('abc','def') in (row('foo'...

With Regards,
Amit Kapila.