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Fix WHERE CURRENT OF to work as designed within plpgsql. The argument
can be the name of a plpgsql cursor variable, which formerly was converted to $N before the core parser saw it, but that's no longer the case. Deal with plain name references to plpgsql variables, and add a regression test case that exposes the failure.
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5 files changed

+107
-39
lines changed

5 files changed

+107
-39
lines changed

‎src/backend/executor/execCurrent.c

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $PostgreSQL: pgsql/src/backend/executor/execCurrent.c,v 1.13 2009/11/04 22:26:05 tgl Exp $
9+
* $PostgreSQL: pgsql/src/backend/executor/execCurrent.c,v 1.14 2009/11/09 02:36:56 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -20,7 +20,7 @@
2020
#include "utils/portal.h"
2121

2222

23-
static char *fetch_param_value(ExprContext *econtext, int paramId);
23+
static char *fetch_cursor_param_value(ExprContext *econtext, int paramId);
2424
static ScanState *search_plan_tree(PlanState *node, Oid table_oid);
2525

2626

@@ -51,7 +51,7 @@ execCurrentOf(CurrentOfExpr *cexpr,
5151
if (cexpr->cursor_name)
5252
cursor_name = cexpr->cursor_name;
5353
else
54-
cursor_name = fetch_param_value(econtext, cexpr->cursor_param);
54+
cursor_name = fetch_cursor_param_value(econtext, cexpr->cursor_param);
5555

5656
/* Fetch table name for possible use in error messages */
5757
table_name = get_rel_name(table_oid);
@@ -203,12 +203,12 @@ execCurrentOf(CurrentOfExpr *cexpr,
203203
}
204204

205205
/*
206-
* fetch_param_value
206+
* fetch_cursor_param_value
207207
*
208208
* Fetch the string value of a param, verifying it is of type REFCURSOR.
209209
*/
210210
static char *
211-
fetch_param_value(ExprContext *econtext, int paramId)
211+
fetch_cursor_param_value(ExprContext *econtext, int paramId)
212212
{
213213
ParamListInfo paramInfo = econtext->ecxt_param_list_info;
214214

‎src/backend/parser/gram.y

Lines changed: 1 addition & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@
1111
*
1212
*
1313
* IDENTIFICATION
14-
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.688 2009/11/05 23:24:23 tgl Exp $
14+
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.689 2009/11/09 02:36:56 tgl Exp $
1515
*
1616
* HISTORY
1717
* AUTHOR DATE MAJOR EVENT
@@ -7979,14 +7979,6 @@ where_or_current_clause:
79797979
n->cursor_param = 0;
79807980
$$ = (Node *) n;
79817981
}
7982-
| WHERE CURRENT_P OF PARAM
7983-
{
7984-
CurrentOfExpr *n = makeNode(CurrentOfExpr);
7985-
/* cvarno is filled in by parse analysis */
7986-
n->cursor_name = NULL;
7987-
n->cursor_param = $4;
7988-
$$ = (Node *) n;
7989-
}
79907982
| /*EMPTY*/ { $$ = NULL; }
79917983
;
79927984

‎src/backend/parser/parse_expr.c

Lines changed: 35 additions & 25 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.247 2009/10/31 01:41:31 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.248 2009/11/09 02:36:56 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -1963,32 +1963,42 @@ transformCurrentOfExpr(ParseState *pstate, CurrentOfExpr *cexpr)
19631963
Assert(sublevels_up == 0);
19641964

19651965
/*
1966-
* If a parameter is used, it must be of type REFCURSOR. To verify
1967-
* that the parameter hooks think so, build a dummy ParamRef and
1968-
* transform it.
1966+
* Check to see if the cursor name matches a parameter of type REFCURSOR.
1967+
* If so, replace the raw name reference with a parameter reference.
1968+
* (This is a hack for the convenience of plpgsql.)
19691969
*/
1970-
if (cexpr->cursor_name == NULL)
1970+
if (cexpr->cursor_name != NULL) /* in case already transformed */
19711971
{
1972-
ParamRef *p = makeNode(ParamRef);
1973-
Node *n;
1974-
1975-
p->number = cexpr->cursor_param;
1976-
p->location = -1;
1977-
n = transformParamRef(pstate, p);
1978-
/* Allow the parameter type to be inferred if it's unknown */
1979-
if (exprType(n) == UNKNOWNOID)
1980-
n = coerce_type(pstate, n, UNKNOWNOID,
1981-
REFCURSOROID, -1,
1982-
COERCION_IMPLICIT, COERCE_IMPLICIT_CAST,
1983-
-1);
1984-
if (exprType(n) != REFCURSOROID)
1985-
ereport(ERROR,
1986-
(errcode(ERRCODE_AMBIGUOUS_PARAMETER),
1987-
errmsg("inconsistent types deduced for parameter $%d",
1988-
cexpr->cursor_param),
1989-
errdetail("%s versus %s",
1990-
format_type_be(exprType(n)),
1991-
format_type_be(REFCURSOROID))));
1972+
ColumnRef *cref = makeNode(ColumnRef);
1973+
Node *node = NULL;
1974+
1975+
/* Build an unqualified ColumnRef with the given name */
1976+
cref->fields = list_make1(makeString(cexpr->cursor_name));
1977+
cref->location = -1;
1978+
1979+
/* See if there is a translation available from a parser hook */
1980+
if (pstate->p_pre_columnref_hook != NULL)
1981+
node = (*pstate->p_pre_columnref_hook) (pstate, cref);
1982+
if (node == NULL && pstate->p_post_columnref_hook != NULL)
1983+
node = (*pstate->p_post_columnref_hook) (pstate, cref, NULL);
1984+
1985+
/*
1986+
* XXX Should we throw an error if we get a translation that isn't
1987+
* a refcursor Param? For now it seems best to silently ignore
1988+
* false matches.
1989+
*/
1990+
if (node != NULL && IsA(node, Param))
1991+
{
1992+
Param *p = (Param *) node;
1993+
1994+
if (p->paramkind == PARAM_EXTERN &&
1995+
p->paramtype == REFCURSOROID)
1996+
{
1997+
/* Matches, so convert CURRENT OF to a param reference */
1998+
cexpr->cursor_name = NULL;
1999+
cexpr->cursor_param = p->paramid;
2000+
}
2001+
}
19922002
}
19932003

19942004
return (Node *) cexpr;

‎src/test/regress/expected/plpgsql.out

Lines changed: 46 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3292,6 +3292,52 @@ select * from forc_test;
32923292
1000 | 20
32933293
(10 rows)
32943294

3295+
-- same, with a cursor whose portal name doesn't match variable name
3296+
create or replace function forc01() returns void as $$
3297+
declare
3298+
c refcursor := 'fooled_ya';
3299+
r record;
3300+
begin
3301+
open c for select * from forc_test;
3302+
loop
3303+
fetch c into r;
3304+
exit when not found;
3305+
raise notice '%, %', r.i, r.j;
3306+
update forc_test set i = i * 100, j = r.j * 2 where current of c;
3307+
end loop;
3308+
end;
3309+
$$ language plpgsql;
3310+
select forc01();
3311+
NOTICE: 100, 2
3312+
NOTICE: 200, 4
3313+
NOTICE: 300, 6
3314+
NOTICE: 400, 8
3315+
NOTICE: 500, 10
3316+
NOTICE: 600, 12
3317+
NOTICE: 700, 14
3318+
NOTICE: 800, 16
3319+
NOTICE: 900, 18
3320+
NOTICE: 1000, 20
3321+
forc01
3322+
--------
3323+
3324+
(1 row)
3325+
3326+
select * from forc_test;
3327+
i | j
3328+
--------+----
3329+
10000 | 4
3330+
20000 | 8
3331+
30000 | 12
3332+
40000 | 16
3333+
50000 | 20
3334+
60000 | 24
3335+
70000 | 28
3336+
80000 | 32
3337+
90000 | 36
3338+
100000 | 40
3339+
(10 rows)
3340+
32953341
drop function forc01();
32963342
-- fail because cursor has no query bound to it
32973343
create or replace function forc_bad() returns void as $$

‎src/test/regress/sql/plpgsql.sql

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2689,6 +2689,26 @@ select forc01();
26892689

26902690
select * from forc_test;
26912691

2692+
-- same, with a cursor whose portal name doesn't match variable name
2693+
create or replace function forc01() returns void as $$
2694+
declare
2695+
c refcursor := 'fooled_ya';
2696+
r record;
2697+
begin
2698+
open c for select * from forc_test;
2699+
loop
2700+
fetch c into r;
2701+
exit when not found;
2702+
raise notice '%, %', r.i, r.j;
2703+
update forc_test set i = i * 100, j = r.j * 2 where current of c;
2704+
end loop;
2705+
end;
2706+
$$ language plpgsql;
2707+
2708+
select forc01();
2709+
2710+
select * from forc_test;
2711+
26922712
drop function forc01();
26932713

26942714
-- fail because cursor has no query bound to it

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