From 9eaf5be5067571febf323337fc58bcac97b9f5d5 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 3 Jun 2016 18:07:14 -0400
Subject: [PATCH] Mark read/write expanded values as read-only in ValuesNext(),
too.
Further thought about bug #14174 motivated me to try the case of a
R/W datum being returned from a VALUES list, and sure enough it was
broken. Fix that.
Also add a regression test case exercising the same scenario for
FunctionScan. That's not broken right now, because the function's
result will get shoved into a tuplestore between generation and use;
but it could easily become broken whenever we get around to optimizing
FunctionScan better.
There don't seem to be any other places where we put the result of
expression evaluation into a virtual tuple slot that could then be
the source for Vars of further expression evaluation, so I think
this is the end of this bug.
---
src/backend/executor/nodeValuesscan.c | 14 ++++++++++++
src/test/regress/expected/plpgsql.out | 32 +++++++++++++++++++++++++++
src/test/regress/sql/plpgsql.sql | 12 ++++++++++
3 files changed, 58 insertions(+)
diff --git a/src/backend/executor/nodeValuesscan.c b/src/backend/executor/nodeValuesscan.c
index 2c4bd9c9277..9c03f8ae166 100644
--- a/src/backend/executor/nodeValuesscan.c
+++ b/src/backend/executor/nodeValuesscan.c
@@ -25,6 +25,7 @@
#include "executor/executor.h"
#include "executor/nodeValuesscan.h"
+#include "utils/expandeddatum.h"
static TupleTableSlot *ValuesNext(ValuesScanState *node);
@@ -94,6 +95,7 @@ ValuesNext(ValuesScanState *node)
List *exprstatelist;
Datum *values;
bool *isnull;
+ Form_pg_attribute *att;
ListCell *lc;
int resind;
@@ -129,6 +131,7 @@ ValuesNext(ValuesScanState *node)
*/
values = slot->tts_values;
isnull = slot->tts_isnull;
+ att = slot->tts_tupleDescriptor->attrs;
resind = 0;
foreach(lc, exprstatelist)
@@ -139,6 +142,17 @@ ValuesNext(ValuesScanState *node)
econtext,
&isnull[resind],
NULL);
+
+ /*
+ * We must force any R/W expanded datums to read-only state, in
+ * case they are multiply referenced in the plan node's output
+ * expressions, or in case we skip the output projection and the
+ * output column is multiply referenced in higher plan nodes.
+ */
+ values[resind] = MakeExpandedObjectReadOnly(values[resind],
+ isnull[resind],
+ att[resind]->attlen);
+
resind++;
}
diff --git a/src/test/regress/expected/plpgsql.out b/src/test/regress/expected/plpgsql.out
index 9563210080a..a2c36e44ba0 100644
--- a/src/test/regress/expected/plpgsql.out
+++ b/src/test/regress/expected/plpgsql.out
@@ -5404,6 +5404,38 @@ select i, a from
1 | {1,1}
(1 row)
+explain (verbose, costs off)
+select consumes_rw_array(a), a from returns_rw_array(1) a;
+ QUERY PLAN
+--------------------------------------------
+ Function Scan on public.returns_rw_array a
+ Output: consumes_rw_array(a), a
+ Function Call: returns_rw_array(1)
+(3 rows)
+
+select consumes_rw_array(a), a from returns_rw_array(1) a;
+ consumes_rw_array | a
+-------------------+-------
+ 1 | {1,1}
+(1 row)
+
+explain (verbose, costs off)
+select consumes_rw_array(a), a from
+ (values (returns_rw_array(1)), (returns_rw_array(2))) v(a);
+ QUERY PLAN
+---------------------------------------------------------------------
+ Values Scan on "*VALUES*"
+ Output: consumes_rw_array("*VALUES*".column1), "*VALUES*".column1
+(2 rows)
+
+select consumes_rw_array(a), a from
+ (values (returns_rw_array(1)), (returns_rw_array(2))) v(a);
+ consumes_rw_array | a
+-------------------+-------
+ 1 | {1,1}
+ 2 | {2,2}
+(2 rows)
+
--
-- Test access to call stack
--
diff --git a/src/test/regress/sql/plpgsql.sql b/src/test/regress/sql/plpgsql.sql
index b1226ea4a0f..776f2292ea5 100644
--- a/src/test/regress/sql/plpgsql.sql
+++ b/src/test/regress/sql/plpgsql.sql
@@ -4263,6 +4263,18 @@ select i, a from
(select returns_rw_array(1) as a offset 0) ss,
lateral consumes_rw_array(a) i;
+explain (verbose, costs off)
+select consumes_rw_array(a), a from returns_rw_array(1) a;
+
+select consumes_rw_array(a), a from returns_rw_array(1) a;
+
+explain (verbose, costs off)
+select consumes_rw_array(a), a from
+ (values (returns_rw_array(1)), (returns_rw_array(2))) v(a);
+
+select consumes_rw_array(a), a from
+ (values (returns_rw_array(1)), (returns_rw_array(2))) v(a);
+
--
-- Test access to call stack
--
GitLab