/* there's no DISTINCT in DELETE */
qry->distinctClause = NIL;
- /* subqueries in USING can see the result relation only via LATERAL */
+ /* subqueries in USING cannot access the result relation */
nsitem->p_lateral_only = true;
+ nsitem->p_lateral_ok = false;
/*
* The USING clause is non-standard SQL syntax, and is equivalent in
*/
transformFromClause(pstate, stmt->usingClause);
- /* remaining clauses can see the result relation normally */
+ /* remaining clauses can reference the result relation normally */
nsitem->p_lateral_only = false;
+ nsitem->p_lateral_ok = true;
qual = transformWhereClause(pstate, stmt->whereClause,
EXPR_KIND_WHERE, "WHERE");
/* grab the namespace item made by setTargetTable */
nsitem = (ParseNamespaceItem *) llast(pstate->p_namespace);
- /* subqueries in FROM can see the result relation only via LATERAL */
+ /* subqueries in FROM cannot access the result relation */
nsitem->p_lateral_only = true;
+ nsitem->p_lateral_ok = false;
/*
* the FROM clause is non-standard SQL syntax. We used to be able to do
*/
transformFromClause(pstate, stmt->fromClause);
- /* remaining clauses can see the result relation normally */
+ /* remaining clauses can reference the result relation normally */
nsitem->p_lateral_only = false;
+ nsitem->p_lateral_ok = true;
qry->targetList = transformTargetList(pstate, stmt->targetList,
EXPR_KIND_UPDATE_SOURCE);
const char *refname, int location);
static RangeTblEntry *scanNameSpaceForRelid(ParseState *pstate, Oid relid,
int location);
+static void check_lateral_ref_ok(ParseState *pstate, ParseNamespaceItem *nsitem,
+ int location);
static void markRTEForSelectPriv(ParseState *pstate, RangeTblEntry *rte,
int rtindex, AttrNumber col);
static void expandRelation(Oid relid, Alias *eref,
errmsg("table reference \"%s\" is ambiguous",
refname),
parser_errposition(pstate, location)));
- /* SQL:2008 demands this be an error, not an invisible item */
- if (nsitem->p_lateral_only && !nsitem->p_lateral_ok)
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
- errmsg("invalid reference to FROM-clause entry for table \"%s\"",
- refname),
- errdetail("The combining JOIN type must be INNER or LEFT for a LATERAL reference."),
- parser_errposition(pstate, location)));
+ check_lateral_ref_ok(pstate, nsitem, location);
result = rte;
}
}
errmsg("table reference %u is ambiguous",
relid),
parser_errposition(pstate, location)));
- /* SQL:2008 demands this be an error, not an invisible item */
- if (nsitem->p_lateral_only && !nsitem->p_lateral_ok)
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
- errmsg("invalid reference to FROM-clause entry for table \"%s\"",
- rte->eref->aliasname),
- errdetail("The combining JOIN type must be INNER or LEFT for a LATERAL reference."),
- parser_errposition(pstate, location)));
+ check_lateral_ref_ok(pstate, nsitem, location);
result = rte;
}
}
}
}
+/*
+ * Complain if a namespace item is currently disallowed as a LATERAL reference.
+ * This enforces both SQL:2008's rather odd idea of what to do with a LATERAL
+ * reference to the wrong side of an outer join, and our own prohibition on
+ * referencing the target table of an UPDATE or DELETE as a lateral reference
+ * in a FROM/USING clause.
+ *
+ * Convenience subroutine to avoid multiple copies of a rather ugly ereport.
+ */
+static void
+check_lateral_ref_ok(ParseState *pstate, ParseNamespaceItem *nsitem,
+ int location)
+{
+ if (nsitem->p_lateral_only && !nsitem->p_lateral_ok)
+ {
+ /* SQL:2008 demands this be an error, not an invisible item */
+ RangeTblEntry *rte = nsitem->p_rte;
+ char *refname = rte->eref->aliasname;
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+ errmsg("invalid reference to FROM-clause entry for table \"%s\"",
+ refname),
+ (rte == pstate->p_target_rangetblentry) ?
+ errhint("There is an entry for table \"%s\", but it cannot be referenced from this part of the query.",
+ refname) :
+ errdetail("The combining JOIN type must be INNER or LEFT for a LATERAL reference."),
+ parser_errposition(pstate, location)));
+ }
+}
+
/*
* given an RTE, return RT index (starting with 1) of the entry,
* and optionally get its nesting depth (0 = current). If sublevels_up
(errcode(ERRCODE_AMBIGUOUS_COLUMN),
errmsg("column reference \"%s\" is ambiguous",
colname),
- parser_errposition(orig_pstate, location)));
- /* SQL:2008 demands this be an error, not an invisible item */
- if (nsitem->p_lateral_only && !nsitem->p_lateral_ok)
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
- errmsg("invalid reference to FROM-clause entry for table \"%s\"",
- rte->eref->aliasname),
- errdetail("The combining JOIN type must be INNER or LEFT for a LATERAL reference."),
- parser_errposition(orig_pstate, location)));
+ parser_errposition(pstate, location)));
+ check_lateral_ref_ok(pstate, nsitem, location);
result = newresult;
}
}
* inside such a subexpression at the moment.) If p_lateral_ok is not set,
* it's an error to actually use such a namespace item. One might think it
* would be better to just exclude such items from visibility, but the wording
- * of SQL:2008 requires us to do it this way.
+ * of SQL:2008 requires us to do it this way. We also use p_lateral_ok to
+ * forbid LATERAL references to an UPDATE/DELETE target table.
*
* At no time should a namespace list contain two entries that conflict
* according to the rules in checkNameSpaceConflicts; but note that those
^
-- check behavior of LATERAL in UPDATE/DELETE
create temp table xx1 as select f1 as x1, -f1 as x2 from int4_tbl;
-select * from xx1;
- x1 | x2
--------------+-------------
- 0 | 0
- 123456 | -123456
- -123456 | 123456
- 2147483647 | -2147483647
- -2147483647 | 2147483647
-(5 rows)
-
--- error, can't do this without LATERAL:
+-- error, can't do this:
update xx1 set x2 = f1 from (select * from int4_tbl where f1 = x1) ss;
ERROR: column "x1" does not exist
LINE 1: ... set x2 = f1 from (select * from int4_tbl where f1 = x1) ss;
LINE 1: ...t x2 = f1 from (select * from int4_tbl where f1 = xx1.x1) ss...
^
HINT: There is an entry for table "xx1", but it cannot be referenced from this part of the query.
--- OK:
+-- can't do it even with LATERAL:
update xx1 set x2 = f1 from lateral (select * from int4_tbl where f1 = x1) ss;
-select * from xx1;
- x1 | x2
--------------+-------------
- 0 | 0
- 123456 | 123456
- -123456 | -123456
- 2147483647 | 2147483647
- -2147483647 | -2147483647
-(5 rows)
-
--- error:
+ERROR: invalid reference to FROM-clause entry for table "xx1"
+LINE 1: ...= f1 from lateral (select * from int4_tbl where f1 = x1) ss;
+ ^
+HINT: There is an entry for table "xx1", but it cannot be referenced from this part of the query.
+-- we might in future allow something like this, but for now it's an error:
+update xx1 set x2 = f1 from xx1, lateral (select * from int4_tbl where f1 = x1) ss;
+ERROR: table name "xx1" specified more than once
+-- also errors:
delete from xx1 using (select * from int4_tbl where f1 = x1) ss;
ERROR: column "x1" does not exist
LINE 1: ...te from xx1 using (select * from int4_tbl where f1 = x1) ss;
^
HINT: There is a column named "x1" in table "xx1", but it cannot be referenced from this part of the query.
--- OK:
+delete from xx1 using (select * from int4_tbl where f1 = xx1.x1) ss;
+ERROR: invalid reference to FROM-clause entry for table "xx1"
+LINE 1: ...from xx1 using (select * from int4_tbl where f1 = xx1.x1) ss...
+ ^
+HINT: There is an entry for table "xx1", but it cannot be referenced from this part of the query.
delete from xx1 using lateral (select * from int4_tbl where f1 = x1) ss;
-select * from xx1;
- x1 | x2
-----+----
-(0 rows)
-
+ERROR: invalid reference to FROM-clause entry for table "xx1"
+LINE 1: ...xx1 using lateral (select * from int4_tbl where f1 = x1) ss;
+ ^
+HINT: There is an entry for table "xx1", but it cannot be referenced from this part of the query.
-- check behavior of LATERAL in UPDATE/DELETE
create temp table xx1 as select f1 as x1, -f1 as x2 from int4_tbl;
-select * from xx1;
--- error, can't do this without LATERAL:
+-- error, can't do this:
update xx1 set x2 = f1 from (select * from int4_tbl where f1 = x1) ss;
update xx1 set x2 = f1 from (select * from int4_tbl where f1 = xx1.x1) ss;
--- OK:
+-- can't do it even with LATERAL:
update xx1 set x2 = f1 from lateral (select * from int4_tbl where f1 = x1) ss;
-select * from xx1;
+-- we might in future allow something like this, but for now it's an error:
+update xx1 set x2 = f1 from xx1, lateral (select * from int4_tbl where f1 = x1) ss;
--- error:
+-- also errors:
delete from xx1 using (select * from int4_tbl where f1 = x1) ss;
--- OK:
+delete from xx1 using (select * from int4_tbl where f1 = xx1.x1) ss;
delete from xx1 using lateral (select * from int4_tbl where f1 = x1) ss;
-select * from xx1;
projects / postgresql / commitdiff