Content-Type: multipart/mixed; boundary="------------9f6W8S1LdvHah4wlpoOSzM0L"
Message-ID: <02aea982-c656-462d-a412-1fb2e388f754@gmail.com>
Date: Sat, 18 Jul 2026 17:38:41 +0200
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re:[patch] BUG #19558: User-defined prefix operators "|" and "->" no
 longer parse in 19beta2 (SQL/PGQ grammar change)
To: pierre@senellart.com, pgsql-bugs@lists.postgresql.org
References: <19558-ad1fca59a3a471a0@postgresql.org>
Content-Language: en-US
From: Pierre Forstmann <pierre.forstmann@gmail.com>
In-Reply-To: <19558-ad1fca59a3a471a0@postgresql.org>
Archived-At: 
 <https://www.postgresql.org/message-id/02aea982-c656-462d-a412-1fb2e388f754%40gmail.com>
Precedence: bulk

This is a multi-part message in MIME format.
--------------9f6W8S1LdvHah4wlpoOSzM0L
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit

Hello,

I propose following patch that adds missing grammar rules:

  src/backend/parser/gram.y | 9 +++++++++
  1 file changed, 9 insertions(+)

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e138..331da79 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -15873,6 +15873,10 @@ a_expr:        c_expr                   { $$ = 
$1; }
                  { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "+", NULL, 
$2, @1); }
              | '-' a_expr                    %prec UMINUS
                  { $$ = doNegate($2, @1); }
+            | '|' a_expr                  %prec UMINUS
+                 { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "|", NULL , 
$2, @1); }
+            | RIGHT_ARROW a_expr                  %prec UMINUS
+                 { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "->", NULL 
, $2, @1); }
              | a_expr '+' a_expr
                  { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "+", $1, 
$3, @2); }
              | a_expr '-' a_expr
@@ -15902,6 +15906,7 @@ a_expr:        c_expr                 { $$ = $1; }
              | a_expr '|' a_expr
                  { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "|", $1, 
$3, @2); }

+
              | a_expr qual_Op a_expr                %prec Op
                  { $$ = (Node *) makeA_Expr(AEXPR_OP, $2, $1, $3, @2); }
              | qual_Op a_expr                    %prec Op
@@ -16355,6 +16360,10 @@ b_expr:        c_expr
                  { $$ = makeTypeCast($1, $3, @2); }
              | '+' b_expr                    %prec UMINUS
                  { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "+", NULL, 
$2, @1); }
+            | '|' b_expr                    %prec UMINUS
+                { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "|", NULL, 
$2, @1); }
+            | RIGHT_ARROW b_expr                    %prec UMINUS
+                { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "->", NULL, 
$2, @1); }
              | '-' b_expr                    %prec UMINUS
                  { $$ = doNegate($2, @1); }
              | b_expr '+' b_expr
-- 
2.52.0

Test case says:


CREATE FUNCTION identity_int(int) RETURNS int
       LANGUAGE sql IMMUTABLE AS 'SELECT $1';
CREATE FUNCTION
CREATE OPERATOR |  (RIGHTARG = int, FUNCTION = identity_int);
CREATE OPERATOR
CREATE OPERATOR -> (RIGHTARG = int, FUNCTION = identity_int);
CREATE OPERATOR
SELECT | 5;
  ?column?
----------
         5
(1 row)

SELECT -> 5;
  ?column?
----------
         5
(1 row)


Le 18/07/2026 à 10:39, PG Bug reporting form a écrit :
> The following bug has been logged on the website:
>
> Bug reference:      19558
> Logged by:          Pierre Senellart
> Email address:      pierre@senellart.com
> PostgreSQL version: 19beta2
> Operating system:   Linux
> Description:
>
> The following works on PostgreSQL <= 18 but raises a syntax error on
> 19beta1/19beta2 (tested: PostgreSQL 19beta2, Ubuntu package
> 19~beta2-1.pgdg26.04+1, x86_64-linux):
>
>      CREATE FUNCTION identity_int(int) RETURNS int
>        LANGUAGE sql IMMUTABLE AS 'SELECT $1';
>      CREATE OPERATOR |  (RIGHTARG = int, FUNCTION = identity_int);
>      CREATE OPERATOR -> (RIGHTARG = int, FUNCTION = identity_int);
>
>      SELECT | 5;    -- 18: returns 5;  19beta2: syntax error at or near "|"
>      SELECT -> 5;   -- 18: returns 5;  19beta2: syntax error at or near "->"
>
> Cause: the SQL/PGQ property graph patch turned "|" and "->" into dedicated
> grammar tokens (RIGHT_ARROW), declared in the precedence list alongside Op.
> Explicit binary productions (a_expr '|' a_expr, a_expr RIGHT_ARROW a_expr)
> preserve infix use, and both tokens were added to the operator-name
> productions, so binary use and the OPERATOR() syntax still work:
>
>      SELECT OPERATOR(public.|) 5;    -- still returns 5 on 19beta2
>      SELECT OPERATOR(public.->) 5;   -- still returns 5 on 19beta2
>
> But no unary counterparts of these productions were added, so a user-defined
> *prefix* operator spelled exactly "|" or "->" can no longer be invoked by
> its bare name. Note the inconsistency: CREATE OPERATOR still accepts both
> names for prefix operators; the resulting operator just cannot be called
> except through OPERATOR().
>
> If the tokenization is here to stay, could unary productions ('|' a_expr,
> RIGHT_ARROW a_expr) be added to restore the pre-19 behaviour? Failing that,
> this seems worth an entry in the release notes' incompatibilities section,
> since nothing currently documents it.
>
> Motivation: https://pgxn.org/dist/provsql/ which I am developing uses prefix
> | as a probabilistic “given” operator. This works on all PostgreSQL versions
> from 10 to 18, but fails on 19beta2.
>
>
>
>
--------------9f6W8S1LdvHah4wlpoOSzM0L
Content-Type: text/x-patch; charset=UTF-8;
 name="0001-bug-19558-Fix-user-defined-prefix-operators-and.patch"
Content-Disposition: attachment;
 filename*0="0001-bug-19558-Fix-user-defined-prefix-operators-and.patch"
Content-Transfer-Encoding: base64
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--------------9f6W8S1LdvHah4wlpoOSzM0L--