Michael Zhilin <m.zhi...@postgrespro.ru> writes:

> Hi Andy,
>
> It looks like v5 is missing in your mail. Could you please check and resend 
> it?

ha, yes.. v5 is really attached this time.

commit eee0b2058f912d0d56282711c5d88bc0b1b75c2f (HEAD -> 
shared_detoast_value_v3)
Author: yizhi.fzh <yizhi....@alibaba-inc.com>
Date:   Tue Jan 23 13:38:34 2024 +0800

    shared detoast feature.
    
    details at https://postgr.es/m/87il4jrk1l.fsf%40163.com

commit eeca405f5ae87e7d4e5496de989ac7b5173bcaa9
Author: yizhi.fzh <yizhi....@alibaba-inc.com>
Date:   Mon Jan 22 15:48:33 2024 +0800

    Introduce a Bitset data struct.
    
    While Bitmapset is designed for variable-length of bits, Bitset is
    designed for fixed-length of bits, the fixed length must be specified at
    the bitset_init stage and keep unchanged at the whole lifespan. Because
    of this, some operations on Bitset is simpler than Bitmapset.
    
    The bitset_clear unsets all the bits but kept the allocated memory, this
    capacity is impossible for bit Bitmapset for some solid reasons and this
    is the main reason to add this data struct.
    
    Also for performance aspect, the functions for Bitset removed some
    unlikely checks, instead with some Asserts.
    
    [1] 
https://postgr.es/m/CAApHDvpdp9LyAoMXvS7iCX-t3VonQM3fTWCmhconEvORrQ%2BZYA%40mail.gmail.com
    [2] https://postgr.es/m/875xzqxbv5.fsf%40163.com


As for the commit "Introduce a Bitset data struct.", the test coverage
is 100% now. So it would be great that people can review this first. 

-- 
Best Regards
Andy Fan

>From eeca405f5ae87e7d4e5496de989ac7b5173bcaa9 Mon Sep 17 00:00:00 2001
From: "yizhi.fzh" <yizhi....@alibaba-inc.com>
Date: Mon, 22 Jan 2024 15:48:33 +0800
Subject: [PATCH v5 1/2] Introduce a Bitset data struct.

While Bitmapset is designed for variable-length of bits, Bitset is
designed for fixed-length of bits, the fixed length must be specified at
the bitset_init stage and keep unchanged at the whole lifespan. Because
of this, some operations on Bitset is simpler than Bitmapset.

The bitset_clear unsets all the bits but kept the allocated memory, this
capacity is impossible for bit Bitmapset for some solid reasons and this
is the main reason to add this data struct.

Also for performance aspect, the functions for Bitset removed some
unlikely checks, instead with some Asserts.

[1] https://postgr.es/m/CAApHDvpdp9LyAoMXvS7iCX-t3VonQM3fTWCmhconEvORrQ%2BZYA%40mail.gmail.com
[2] https://postgr.es/m/875xzqxbv5.fsf%40163.com
---
 src/backend/nodes/bitmapset.c                 | 201 +++++++++++++++++-
 src/backend/nodes/outfuncs.c                  |  51 +++++
 src/include/nodes/bitmapset.h                 |  28 +++
 src/include/nodes/nodes.h                     |   4 +
 src/test/modules/test_misc/Makefile           |  11 +
 src/test/modules/test_misc/README             |   4 +-
 .../test_misc/expected/test_bitset.out        |   7 +
 src/test/modules/test_misc/meson.build        |  17 ++
 .../modules/test_misc/sql/test_bitset.sql     |   3 +
 src/test/modules/test_misc/test_misc--1.0.sql |   5 +
 src/test/modules/test_misc/test_misc.c        | 132 ++++++++++++
 src/test/modules/test_misc/test_misc.control  |   4 +
 src/tools/pgindent/typedefs.list              |   1 +
 13 files changed, 456 insertions(+), 12 deletions(-)
 create mode 100644 src/test/modules/test_misc/expected/test_bitset.out
 create mode 100644 src/test/modules/test_misc/sql/test_bitset.sql
 create mode 100644 src/test/modules/test_misc/test_misc--1.0.sql
 create mode 100644 src/test/modules/test_misc/test_misc.c
 create mode 100644 src/test/modules/test_misc/test_misc.control

diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index 65805d4527..eb38834e21 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -1315,23 +1315,18 @@ bms_join(Bitmapset *a, Bitmapset *b)
  * It makes no difference in simple loop usage, but complex iteration logic
  * might need such an ability.
  */
-int
-bms_next_member(const Bitmapset *a, int prevbit)
+
+static int
+bms_next_member_internal(int nwords, const bitmapword *words, int prevbit)
 {
-	int			nwords;
 	int			wordnum;
 	bitmapword	mask;
 
-	Assert(bms_is_valid_set(a));
-
-	if (a == NULL)
-		return -2;
-	nwords = a->nwords;
 	prevbit++;
 	mask = (~(bitmapword) 0) << BITNUM(prevbit);
 	for (wordnum = WORDNUM(prevbit); wordnum < nwords; wordnum++)
 	{
-		bitmapword	w = a->words[wordnum];
+		bitmapword	w = words[wordnum];
 
 		/* ignore bits before prevbit */
 		w &= mask;
@@ -1348,9 +1343,23 @@ bms_next_member(const Bitmapset *a, int prevbit)
 		/* in subsequent words, consider all bits */
 		mask = (~(bitmapword) 0);
 	}
+
 	return -2;
 }
 
+int
+bms_next_member(const Bitmapset *a, int prevbit)
+{
+	Assert(a == NULL || IsA(a, Bitmapset));
+
+	Assert(bms_is_valid_set(a));
+
+	if (a == NULL)
+		return -2;
+
+	return bms_next_member_internal(a->nwords, a->words, prevbit);
+}
+
 /*
  * bms_prev_member - find prev member of a set
  *
@@ -1458,3 +1467,177 @@ bitmap_match(const void *key1, const void *key2, Size keysize)
 	return !bms_equal(*((const Bitmapset *const *) key1),
 					  *((const Bitmapset *const *) key2));
 }
+
+/*
+ * bitset_init - create a Bitset. the set will be round up to nwords;
+ */
+Bitset *
+bitset_init(size_t size)
+{
+	int			nword = size + BITS_PER_BITMAPWORD - 1 / BITS_PER_BITMAPWORD;
+	Bitset	   *result;
+
+	if (size == 0)
+		return NULL;
+
+	result = (Bitset *) palloc0(sizeof(Bitset *) + nword * sizeof(bitmapword));
+	result->nwords = nword;
+
+	return result;
+}
+
+/*
+ * bitset_clear - clear the bits only, but the memory is still there.
+ */
+void
+bitset_clear(Bitset *a)
+{
+	if (a != NULL)
+		memset(a->words, 0, sizeof(bitmapword) * a->nwords);
+}
+
+void
+bitset_free(Bitset *a)
+{
+	if (a != NULL)
+		pfree(a);
+}
+
+bool
+bitset_is_empty(Bitset *a)
+{
+	int			i;
+
+	if (a == NULL)
+		return true;
+
+	for (i = 0; i < a->nwords; i++)
+	{
+		bitmapword	w = a->words[i];
+
+		if (w != 0)
+			return false;
+	}
+
+	return true;
+}
+
+Bitset *
+bitset_copy(Bitset *a)
+{
+	Bitset	   *result;
+
+	if (a == NULL)
+		return NULL;
+
+	result = bitset_init(a->nwords * BITS_PER_BITMAPWORD);
+
+	memcpy(result->words, a->words, sizeof(bitmapword) * a->nwords);
+	return result;
+}
+
+void
+bitset_add_member(Bitset *a, int x)
+{
+	int			wordnum,
+				bitnum;
+
+	Assert(x >= 0);
+
+	wordnum = WORDNUM(x);
+	bitnum = BITNUM(x);
+
+	Assert(wordnum < a->nwords);
+
+	a->words[wordnum] |= ((bitmapword) 1 << bitnum);
+}
+
+void
+bitset_del_member(Bitset *a, int x)
+{
+	int			wordnum,
+				bitnum;
+
+	Assert(x >= 0);
+
+	wordnum = WORDNUM(x);
+	bitnum = BITNUM(x);
+
+	Assert(wordnum < a->nwords);
+
+	a->words[wordnum] &= ~((bitmapword) 1 << bitnum);
+}
+
+int
+bitset_is_member(int x, Bitset *a)
+{
+	int			wordnum,
+				bitnum;
+
+	/* used in expression engine */
+	Assert(x >= 0);
+
+	wordnum = WORDNUM(x);
+	bitnum = BITNUM(x);
+
+	if (a == NULL)
+		return false;
+
+	if (wordnum >= a->nwords)
+		return false;
+
+	return (a->words[wordnum] & ((bitmapword) 1 << bitnum)) != 0;
+}
+
+int
+bitset_next_member(const Bitset *a, int prevbit)
+{
+	if (a == NULL)
+		return -2;
+
+	return bms_next_member_internal(a->nwords, a->words, prevbit);
+}
+
+
+/*
+ * bitset_to_bitmap - build a legal bitmapset from bitset.
+ */
+Bitmapset *
+bitset_to_bitmap(Bitset *a)
+{
+	int			n;
+
+	bool		found = false;	/* any non-empty bits */
+	Bitmapset  *result;
+	int			i;
+
+	if (a == NULL)
+		return NULL;
+
+	n = a->nwords - 1;
+	do
+	{
+		if (a->words[n] > 0)
+		{
+			found = true;
+			break;
+		}
+	} while (--n >= 0);
+
+	if (!found)
+		return NULL;
+
+	result = (Bitmapset *) palloc0(BITMAPSET_SIZE(n + 1));
+	result->type = T_Bitmapset;
+	result->nwords = n + 1;
+
+	Assert(result->nwords <= a->nwords);
+
+	i = 0;
+	do
+	{
+		result->words[i] = a->words[i];
+	} while (++i < result->nwords);
+
+	return result;
+}
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 296ba84518..2607cd2bfd 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -331,6 +331,43 @@ outBitmapset(StringInfo str, const Bitmapset *bms)
 	appendStringInfoChar(str, ')');
 }
 
+
+
+/*
+ * outBitset -
+ *	similar to outBitmapset, but for Bitset.
+ */
+static void
+outBitsetInternal(struct StringInfoData *str,
+				  const struct Bitset *bs,
+				  bool asBitmap)
+{
+	int			x;
+
+	appendStringInfoChar(str, '(');
+	if (asBitmap)
+		appendStringInfoChar(str, 'b');
+	else
+		appendStringInfo(str, "bs");
+	x = -1;
+	while ((x = bitset_next_member(bs, x)) >= 0)
+		appendStringInfo(str, " %d", x);
+	appendStringInfoChar(str, ')');
+}
+
+
+/*
+ * outBitset -
+ *	similar to outBitmapset, but for Bitset.
+ */
+void
+outBitset(struct StringInfoData *str,
+		  const struct Bitset *bs)
+{
+	outBitsetInternal(str, bs, false);
+}
+
+
 /*
  * Print the value of a Datum given its type.
  */
@@ -904,3 +941,17 @@ bmsToString(const Bitmapset *bms)
 	outBitmapset(&str, bms);
 	return str.data;
 }
+
+/*
+ * bitsetToString -
+ *	   similar to bmsToString, but for Bitset
+ */
+char *
+bitsetToString(const struct Bitset *bs, bool asBitmap)
+{
+	StringInfoData str;
+
+	initStringInfo(&str);
+	outBitsetInternal(&str, bs, asBitmap);
+	return str.data;
+}
diff --git a/src/include/nodes/bitmapset.h b/src/include/nodes/bitmapset.h
index 906e8dcc15..95ff37c6e9 100644
--- a/src/include/nodes/bitmapset.h
+++ b/src/include/nodes/bitmapset.h
@@ -55,6 +55,24 @@ typedef struct Bitmapset
 	bitmapword	words[FLEXIBLE_ARRAY_MEMBER];	/* really [nwords] */
 } Bitmapset;
 
+/*
+ * While Bitmapset is designed for variable-length of bits, Bitset is
+ * designed for fixed-length of bits, the fixed length must be specified at
+ * the bitset_init stage and keep unchanged at the whole lifespan. Because
+ * of this, some operations on Bitset is simpler than Bitmapset.
+ *
+ * The bitset_clear unsets all the bits but kept the allocated memory, this
+ * capacity is impossible for bit Bitmapset for some solid reasons.
+ *
+ * Also for performance aspect, the functions for Bitset removed some
+ * unlikely checks, instead with some Asserts.
+ */
+
+typedef struct Bitset
+{
+	int			nwords;			/* number of words in array */
+	bitmapword	words[FLEXIBLE_ARRAY_MEMBER];	/* really [nwords] */
+} Bitset;
 
 /* result of bms_subset_compare */
 typedef enum
@@ -124,4 +142,14 @@ extern uint32 bms_hash_value(const Bitmapset *a);
 extern uint32 bitmap_hash(const void *key, Size keysize);
 extern int	bitmap_match(const void *key1, const void *key2, Size keysize);
 
+extern Bitset *bitset_init(size_t size);
+extern void bitset_clear(Bitset *a);
+extern void bitset_free(Bitset *a);
+extern bool bitset_is_empty(Bitset *a);
+extern Bitset *bitset_copy(Bitset *a);
+extern void bitset_add_member(Bitset *a, int x);
+extern void bitset_del_member(Bitset *a, int x);
+extern int	bitset_is_member(int bit, Bitset *a);
+extern int	bitset_next_member(const Bitset *a, int prevbit);
+extern Bitmapset *bitset_to_bitmap(Bitset *a);
 #endif							/* BITMAPSET_H */
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 2969dd831b..4d13107990 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -186,16 +186,20 @@ castNodeImpl(NodeTag type, void *ptr)
  * nodes/{outfuncs.c,print.c}
  */
 struct Bitmapset;				/* not to include bitmapset.h here */
+struct Bitset;					/* not to include bitmapset.h here */
 struct StringInfoData;			/* not to include stringinfo.h here */
 
 extern void outNode(struct StringInfoData *str, const void *obj);
 extern void outToken(struct StringInfoData *str, const char *s);
 extern void outBitmapset(struct StringInfoData *str,
 						 const struct Bitmapset *bms);
+extern void outBitset(struct StringInfoData *str, const struct Bitset *bs);
+
 extern void outDatum(struct StringInfoData *str, uintptr_t value,
 					 int typlen, bool typbyval);
 extern char *nodeToString(const void *obj);
 extern char *bmsToString(const struct Bitmapset *bms);
+extern char *bitsetToString(const struct Bitset *bs, bool asBitmap);
 
 /*
  * nodes/{readfuncs.c,read.c}
diff --git a/src/test/modules/test_misc/Makefile b/src/test/modules/test_misc/Makefile
index 39c6c2014a..af96604096 100644
--- a/src/test/modules/test_misc/Makefile
+++ b/src/test/modules/test_misc/Makefile
@@ -2,6 +2,17 @@
 
 TAP_TESTS = 1
 
+MODULE_big = test_misc
+OBJS = \
+	$(WIN32RES) \
+	test_misc.o
+PGFILEDESC = "test_misc"
+
+EXTENSION = test_misc
+DATA = test_misc--1.0.sql
+
+REGRESS = test_bitset
+
 ifdef USE_PGXS
 PG_CONFIG = pg_config
 PGXS := $(shell $(PG_CONFIG) --pgxs)
diff --git a/src/test/modules/test_misc/README b/src/test/modules/test_misc/README
index 4876733fa2..ec426c4ad5 100644
--- a/src/test/modules/test_misc/README
+++ b/src/test/modules/test_misc/README
@@ -1,4 +1,2 @@
-This directory doesn't actually contain any extension module.
-
-What it is is a home for otherwise-unclassified TAP tests that exercise core
+What it is is a home for otherwise-unclassified tests that exercise core
 server features.  We might equally well have called it, say, src/test/misc.
diff --git a/src/test/modules/test_misc/expected/test_bitset.out b/src/test/modules/test_misc/expected/test_bitset.out
new file mode 100644
index 0000000000..3d0302d30d
--- /dev/null
+++ b/src/test/modules/test_misc/expected/test_bitset.out
@@ -0,0 +1,7 @@
+CREATE EXTENSION test_misc;
+SELECT test_bitset();
+ test_bitset 
+-------------
+ 
+(1 row)
+
diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build
index 964d95db26..a23f3e3f47 100644
--- a/src/test/modules/test_misc/meson.build
+++ b/src/test/modules/test_misc/meson.build
@@ -1,5 +1,22 @@
 # Copyright (c) 2022-2024, PostgreSQL Global Development Group
 
+test_misc_sources = files(
+    'test_misc.c',
+)
+
+if host_system == 'windows'
+  test_misc_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+    '--NAME', 'test_misc',
+    '--FILEDESC', 'test_misc - ',])
+endif
+
+test_misc = shared_module('test_misc',
+  test_misc_sources,
+  kwargs: pg_test_mod_args,
+)
+
+test_install_libs += test_misc
+
 tests += {
   'name': 'test_misc',
   'sd': meson.current_source_dir(),
diff --git a/src/test/modules/test_misc/sql/test_bitset.sql b/src/test/modules/test_misc/sql/test_bitset.sql
new file mode 100644
index 0000000000..0f73bbf532
--- /dev/null
+++ b/src/test/modules/test_misc/sql/test_bitset.sql
@@ -0,0 +1,3 @@
+CREATE EXTENSION test_misc;
+
+SELECT test_bitset();
diff --git a/src/test/modules/test_misc/test_misc--1.0.sql b/src/test/modules/test_misc/test_misc--1.0.sql
new file mode 100644
index 0000000000..79afaa6263
--- /dev/null
+++ b/src/test/modules/test_misc/test_misc--1.0.sql
@@ -0,0 +1,5 @@
+\echo Use "CREATE EXTENSION test_misc" to load this file. \quit
+
+CREATE FUNCTION test_bitset()
+       RETURNS pg_catalog.void
+       AS 'MODULE_PATHNAME' LANGUAGE C;
diff --git a/src/test/modules/test_misc/test_misc.c b/src/test/modules/test_misc/test_misc.c
new file mode 100644
index 0000000000..8cc8d6fc1e
--- /dev/null
+++ b/src/test/modules/test_misc/test_misc.c
@@ -0,0 +1,132 @@
+/*--------------------------------------------------------------------------
+ *
+ * test_misc.c
+ *
+ * Copyright (c) 2022-2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		src/test/modules/test_dsa/test_misc.c
+ *
+ * -------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "fmgr.h"
+#include "nodes/bitmapset.h"
+#include "nodes/nodes.h"
+
+#define BIT_ADD 0
+#define BIT_DEL 1
+
+static void compare_bms_bs(Bitmapset **bms, Bitset *bs, int member, int op);
+
+
+PG_MODULE_MAGIC;
+
+/* Test basic DSA functionality */
+PG_FUNCTION_INFO_V1(test_bitset);
+
+Datum
+test_bitset(PG_FUNCTION_ARGS)
+{
+	Bitset	   *bs;
+	Bitset	   *bs2;
+	char	   *str1,
+			   *str2,
+			   *empty_str;
+	Bitmapset  *bms = NULL;
+	int			i;
+
+	empty_str = bmsToString(NULL);
+
+	/* size = 0 */
+	bs = bitset_init(0);
+	Assert(bs == NULL);
+	bitset_clear(bs);
+	Assert(bitset_is_empty(bs));
+	/* bitset_add_member(bs, 0); // crash. */
+	/* bitset_del_member(bs, 0); // crash. */
+	Assert(!bitset_is_member(0, bs));
+	Assert(bitset_next_member(bs, -1) == -2);
+	bs2 = bitset_copy(bs);
+	Assert(bs2 == NULL);
+	bitset_free(bs);
+	bitset_free(bs2);
+
+	/* size == 68, nword == 2 */
+	bs = bitset_init(68);
+
+	for (i = 0; i < 68; i = i + 3)
+	{
+		compare_bms_bs(&bms, bs, i, BIT_ADD);
+	}
+
+	for (i = 67; i >= 0; i = i - 3)
+	{
+		compare_bms_bs(&bms, bs, i, BIT_DEL);
+	}
+
+	bitset_clear(bs);
+	str1 = bitsetToString(bs, true);
+	Assert(strcmp(str1, empty_str) == 0);
+
+	bms = bitset_to_bitmap(bs);
+	str2 = bmsToString(bms);
+	Assert(strcmp(str1, str2) == 0);
+
+	bms = bitset_to_bitmap(NULL);
+	Assert(strcmp(bmsToString(bms), empty_str) == 0);
+
+	bitset_free(bs);
+
+	PG_RETURN_VOID();
+}
+
+
+static void
+compare_bms_bs(Bitmapset **bms, Bitset *bs, int member, int op)
+{
+	char	   *str1,
+			   *str2,
+			   *str3,
+			   *str4;
+	Bitmapset  *bms3;
+	Bitset	   *bs4;
+
+	if (op == BIT_ADD)
+	{
+		*bms = bms_add_member(*bms, member);
+		bitset_add_member(bs, member);
+		Assert(bms_is_member(member, *bms));
+		Assert(bitset_is_member(member, bs));
+	}
+	else if (op == BIT_DEL)
+	{
+		*bms = bms_del_member(*bms, member);
+		bitset_del_member(bs, member);
+		Assert(!bms_is_member(member, *bms));
+		Assert(!bitset_is_member(member, bs));
+	}
+	else
+		Assert(false);
+
+	/* compare the rest existing bit */
+	str1 = bmsToString(*bms);
+	str2 = bitsetToString(bs, true);
+	Assert(strcmp(str1, str2) == 0);
+
+	/* test bitset_to_bitmap */
+	bms3 = bitset_to_bitmap(bs);
+	str3 = bmsToString(bms3);
+	Assert(strcmp(str3, str2) == 0);
+
+	/* test bitset_copy */
+	bs4 = bitset_copy(bs);
+	str4 = bitsetToString(bs4, true);
+	Assert(strcmp(str3, str4) == 0);
+
+	pfree(str1);
+	pfree(str2);
+	pfree(str3);
+	pfree(str4);
+}
diff --git a/src/test/modules/test_misc/test_misc.control b/src/test/modules/test_misc/test_misc.control
new file mode 100644
index 0000000000..48fd08758f
--- /dev/null
+++ b/src/test/modules/test_misc/test_misc.control
@@ -0,0 +1,4 @@
+comment = 'Test misc'
+default_version = '1.0'
+module_pathname = '$libdir/test_misc'
+relocatable = true
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 7e866e3c3d..50b06fd878 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -267,6 +267,7 @@ BitmapOr
 BitmapOrPath
 BitmapOrState
 Bitmapset
+Bitset
 Block
 BlockId
 BlockIdData
-- 
2.34.1

>From eee0b2058f912d0d56282711c5d88bc0b1b75c2f Mon Sep 17 00:00:00 2001
From: "yizhi.fzh" <yizhi....@alibaba-inc.com>
Date: Tue, 23 Jan 2024 13:38:34 +0800
Subject: [PATCH v5 2/2] shared detoast feature.

details at https://postgr.es/m/87il4jrk1l.fsf%40163.com
---
 src/backend/executor/execExpr.c         |  35 +-
 src/backend/executor/execExprInterp.c   | 180 ++++++++
 src/backend/executor/execTuples.c       | 135 ++++++
 src/backend/executor/execUtils.c        |   2 +
 src/backend/executor/nodeHashjoin.c     |   2 +
 src/backend/executor/nodeMergejoin.c    |   2 +
 src/backend/executor/nodeNestloop.c     |   1 +
 src/backend/jit/llvm/llvmjit_expr.c     |  26 +-
 src/backend/jit/llvm/llvmjit_types.c    |   1 +
 src/backend/optimizer/plan/createplan.c |  94 ++++-
 src/backend/optimizer/plan/setrefs.c    | 528 +++++++++++++++++++-----
 src/include/executor/execExpr.h         |   6 +
 src/include/executor/tuptable.h         |  60 +++
 src/include/nodes/execnodes.h           |   4 +
 src/include/nodes/plannodes.h           |  47 +++
 src/tools/pgindent/typedefs.list        |   2 +
 16 files changed, 1019 insertions(+), 106 deletions(-)

diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index 91df2009be..776d4623d1 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -932,22 +932,51 @@ ExecInitExprRec(Expr *node, ExprState *state,
 				}
 				else
 				{
+					int			attnum;
+					Plan	   *plan = state->parent ? state->parent->plan : NULL;
+
 					/* regular user column */
 					scratch.d.var.attnum = variable->varattno - 1;
 					scratch.d.var.vartype = variable->vartype;
+					attnum = scratch.d.var.attnum;
+
 					switch (variable->varno)
 					{
 						case INNER_VAR:
-							scratch.opcode = EEOP_INNER_VAR;
+
+							if (is_join_plan(plan) &&
+								bms_is_member(attnum,
+											  ((JoinState *) state->parent)->inner_pre_detoast_attrs))
+							{
+								scratch.opcode = EEOP_INNER_VAR_TOAST;
+							}
+							else
+							{
+								scratch.opcode = EEOP_INNER_VAR;
+							}
 							break;
 						case OUTER_VAR:
-							scratch.opcode = EEOP_OUTER_VAR;
+							if (is_join_plan(plan) &&
+								bms_is_member(attnum,
+											  ((JoinState *) state->parent)->outer_pre_detoast_attrs))
+							{
+								scratch.opcode = EEOP_OUTER_VAR_TOAST;
+							}
+							else
+								scratch.opcode = EEOP_OUTER_VAR;
 							break;
 
 							/* INDEX_VAR is handled by default case */
 
 						default:
-							scratch.opcode = EEOP_SCAN_VAR;
+							if (is_scan_plan(plan) && bms_is_member(
+																	attnum,
+																	((ScanState *) state->parent)->scan_pre_detoast_attrs))
+							{
+								scratch.opcode = EEOP_SCAN_VAR_TOAST;
+							}
+							else
+								scratch.opcode = EEOP_SCAN_VAR;
 							break;
 					}
 				}
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 3c17cc6b1e..f3cd365a09 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -57,6 +57,7 @@
 #include "postgres.h"
 
 #include "access/heaptoast.h"
+#include "access/detoast.h"
 #include "catalog/pg_type.h"
 #include "commands/sequence.h"
 #include "executor/execExpr.h"
@@ -157,6 +158,9 @@ static void ExecEvalRowNullInt(ExprState *state, ExprEvalStep *op,
 static Datum ExecJustInnerVar(ExprState *state, ExprContext *econtext, bool *isnull);
 static Datum ExecJustOuterVar(ExprState *state, ExprContext *econtext, bool *isnull);
 static Datum ExecJustScanVar(ExprState *state, ExprContext *econtext, bool *isnull);
+static Datum ExecJustInnerVarToast(ExprState *state, ExprContext *econtext, bool *isnull);
+static Datum ExecJustOuterVarToast(ExprState *state, ExprContext *econtext, bool *isnull);
+static Datum ExecJustScanVarToast(ExprState *state, ExprContext *econtext, bool *isnull);
 static Datum ExecJustAssignInnerVar(ExprState *state, ExprContext *econtext, bool *isnull);
 static Datum ExecJustAssignOuterVar(ExprState *state, ExprContext *econtext, bool *isnull);
 static Datum ExecJustAssignScanVar(ExprState *state, ExprContext *econtext, bool *isnull);
@@ -165,6 +169,9 @@ static Datum ExecJustConst(ExprState *state, ExprContext *econtext, bool *isnull
 static Datum ExecJustInnerVarVirt(ExprState *state, ExprContext *econtext, bool *isnull);
 static Datum ExecJustOuterVarVirt(ExprState *state, ExprContext *econtext, bool *isnull);
 static Datum ExecJustScanVarVirt(ExprState *state, ExprContext *econtext, bool *isnull);
+static Datum ExecJustInnerVarVirtToast(ExprState *state, ExprContext *econtext, bool *isnull);
+static Datum ExecJustOuterVarVirtToast(ExprState *state, ExprContext *econtext, bool *isnull);
+static Datum ExecJustScanVarVirtToast(ExprState *state, ExprContext *econtext, bool *isnull);
 static Datum ExecJustAssignInnerVarVirt(ExprState *state, ExprContext *econtext, bool *isnull);
 static Datum ExecJustAssignOuterVarVirt(ExprState *state, ExprContext *econtext, bool *isnull);
 static Datum ExecJustAssignScanVarVirt(ExprState *state, ExprContext *econtext, bool *isnull);
@@ -180,6 +187,43 @@ static pg_attribute_always_inline void ExecAggPlainTransByRef(AggState *aggstate
 															  AggStatePerGroup pergroup,
 															  ExprContext *aggcontext,
 															  int setno);
+static inline void
+ExecSlotDetoastDatum(TupleTableSlot *slot, int attnum)
+{
+	if (!slot->tts_isnull[attnum] &&
+		VARATT_IS_EXTENDED(slot->tts_values[attnum]))
+	{
+		Datum		oldDatum;
+		MemoryContext old = MemoryContextSwitchTo(slot->tts_mcxt);
+
+		oldDatum = slot->tts_values[attnum];
+		slot->tts_values[attnum] = PointerGetDatum(detoast_attr(
+																(struct varlena *) oldDatum));
+		Assert(slot->tts_nvalid > attnum);
+		if (oldDatum != slot->tts_values[attnum])
+			bitset_add_member(slot->pre_detoasted_attrs, attnum);
+		MemoryContextSwitchTo(old);
+	}
+}
+
+/* JIT requires a non-static (and external?) function */
+void
+ExecSlotDetoastDatumExternal(TupleTableSlot *slot, int attnum)
+{
+	return ExecSlotDetoastDatum(slot, attnum);
+}
+
+
+static inline void
+ExecEvalToastVar(TupleTableSlot *slot,
+				 ExprEvalStep *op,
+				 int attnum)
+{
+	ExecSlotDetoastDatum(slot, attnum);
+
+	*op->resvalue = slot->tts_values[attnum];
+	*op->resnull = slot->tts_isnull[attnum];
+}
 
 /*
  * ScalarArrayOpExprHashEntry
@@ -295,6 +339,24 @@ ExecReadyInterpretedExpr(ExprState *state)
 			state->evalfunc_private = (void *) ExecJustScanVar;
 			return;
 		}
+		if (step0 == EEOP_INNER_FETCHSOME &&
+			step1 == EEOP_INNER_VAR_TOAST)
+		{
+			state->evalfunc_private = (void *) ExecJustInnerVarToast;
+			return;
+		}
+		else if (step0 == EEOP_OUTER_FETCHSOME &&
+				 step1 == EEOP_OUTER_VAR_TOAST)
+		{
+			state->evalfunc_private = (void *) ExecJustOuterVarToast;
+			return;
+		}
+		else if (step0 == EEOP_SCAN_FETCHSOME &&
+				 step1 == EEOP_SCAN_VAR_TOAST)
+		{
+			state->evalfunc_private = (void *) ExecJustScanVarToast;
+			return;
+		}
 		else if (step0 == EEOP_INNER_FETCHSOME &&
 				 step1 == EEOP_ASSIGN_INNER_VAR)
 		{
@@ -345,6 +407,21 @@ ExecReadyInterpretedExpr(ExprState *state)
 			state->evalfunc_private = (void *) ExecJustScanVarVirt;
 			return;
 		}
+		else if (step0 == EEOP_INNER_VAR_TOAST)
+		{
+			state->evalfunc_private = (void *) ExecJustInnerVarVirtToast;
+			return;
+		}
+		else if (step0 == EEOP_OUTER_VAR_TOAST)
+		{
+			state->evalfunc_private = (void *) ExecJustOuterVarVirtToast;
+			return;
+		}
+		else if (step0 == EEOP_SCAN_VAR_TOAST)
+		{
+			state->evalfunc_private = (void *) ExecJustScanVarVirtToast;
+			return;
+		}
 		else if (step0 == EEOP_ASSIGN_INNER_VAR)
 		{
 			state->evalfunc_private = (void *) ExecJustAssignInnerVarVirt;
@@ -412,6 +489,9 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 		&&CASE_EEOP_INNER_VAR,
 		&&CASE_EEOP_OUTER_VAR,
 		&&CASE_EEOP_SCAN_VAR,
+		&&CASE_EEOP_INNER_VAR_TOAST,
+		&&CASE_EEOP_OUTER_VAR_TOAST,
+		&&CASE_EEOP_SCAN_VAR_TOAST,
 		&&CASE_EEOP_INNER_SYSVAR,
 		&&CASE_EEOP_OUTER_SYSVAR,
 		&&CASE_EEOP_SCAN_SYSVAR,
@@ -595,6 +675,25 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 			Assert(attnum >= 0 && attnum < scanslot->tts_nvalid);
 			*op->resvalue = scanslot->tts_values[attnum];
 			*op->resnull = scanslot->tts_isnull[attnum];
+			EEO_NEXT();
+		}
+
+		EEO_CASE(EEOP_INNER_VAR_TOAST)
+		{
+			ExecEvalToastVar(innerslot, op, op->d.var.attnum);
+			EEO_NEXT();
+		}
+
+		EEO_CASE(EEOP_OUTER_VAR_TOAST)
+		{
+			ExecEvalToastVar(outerslot, op, op->d.var.attnum);
+
+			EEO_NEXT();
+		}
+
+		EEO_CASE(EEOP_SCAN_VAR_TOAST)
+		{
+			ExecEvalToastVar(scanslot, op, op->d.var.attnum);
 
 			EEO_NEXT();
 		}
@@ -2126,6 +2225,42 @@ ExecJustScanVar(ExprState *state, ExprContext *econtext, bool *isnull)
 	return ExecJustVarImpl(state, econtext->ecxt_scantuple, isnull);
 }
 
+static pg_attribute_always_inline Datum
+ExecJustVarImplToast(ExprState *state, TupleTableSlot *slot, bool *isnull)
+{
+	ExprEvalStep *op = &state->steps[1];
+	int			attnum = op->d.var.attnum;
+
+	CheckOpSlotCompatibility(&state->steps[0], slot);
+
+	slot_getattr(slot, attnum + 1, isnull);
+
+	ExecSlotDetoastDatum(slot, attnum);
+
+	return slot->tts_values[attnum];
+}
+
+/* Simple reference to inner Var */
+static Datum
+ExecJustInnerVarToast(ExprState *state, ExprContext *econtext, bool *isnull)
+{
+	return ExecJustVarImplToast(state, econtext->ecxt_innertuple, isnull);
+}
+
+/* Simple reference to outer Var */
+static Datum
+ExecJustOuterVarToast(ExprState *state, ExprContext *econtext, bool *isnull)
+{
+	return ExecJustVarImplToast(state, econtext->ecxt_outertuple, isnull);
+}
+
+/* Simple reference to scan Var */
+static Datum
+ExecJustScanVarToast(ExprState *state, ExprContext *econtext, bool *isnull)
+{
+	return ExecJustVarImplToast(state, econtext->ecxt_scantuple, isnull);
+}
+
 /* implementation of ExecJustAssign(Inner|Outer|Scan)Var */
 static pg_attribute_always_inline Datum
 ExecJustAssignVarImpl(ExprState *state, TupleTableSlot *inslot, bool *isnull)
@@ -2264,6 +2399,51 @@ ExecJustScanVarVirt(ExprState *state, ExprContext *econtext, bool *isnull)
 	return ExecJustVarVirtImpl(state, econtext->ecxt_scantuple, isnull);
 }
 
+/* implementation of ExecJust(Inner|Outer|Scan)VarVirt */
+static pg_attribute_always_inline Datum
+ExecJustVarVirtImplToast(ExprState *state, TupleTableSlot *slot, bool *isnull)
+{
+	ExprEvalStep *op = &state->steps[0];
+	int			attnum = op->d.var.attnum;
+
+	/*
+	 * As it is guaranteed that a virtual slot is used, there never is a need
+	 * to perform tuple deforming (nor would it be possible). Therefore
+	 * execExpr.c has not emitted an EEOP_*_FETCHSOME step. Verify, as much as
+	 * possible, that that determination was accurate.
+	 */
+	Assert(TTS_IS_VIRTUAL(slot));
+	Assert(TTS_FIXED(slot));
+	Assert(attnum >= 0 && attnum < slot->tts_nvalid);
+
+	*isnull = slot->tts_isnull[attnum];
+
+	ExecSlotDetoastDatum(slot, attnum);
+
+	return slot->tts_values[attnum];
+}
+
+/* Like ExecJustInnerVar, optimized for virtual slots */
+static Datum
+ExecJustInnerVarVirtToast(ExprState *state, ExprContext *econtext, bool *isnull)
+{
+	return ExecJustVarVirtImplToast(state, econtext->ecxt_innertuple, isnull);
+}
+
+/* Like ExecJustOuterVar, optimized for virtual slots */
+static Datum
+ExecJustOuterVarVirtToast(ExprState *state, ExprContext *econtext, bool *isnull)
+{
+	return ExecJustVarVirtImplToast(state, econtext->ecxt_outertuple, isnull);
+}
+
+/* Like ExecJustScanVar, optimized for virtual slots */
+static Datum
+ExecJustScanVarVirtToast(ExprState *state, ExprContext *econtext, bool *isnull)
+{
+	return ExecJustVarVirtImplToast(state, econtext->ecxt_scantuple, isnull);
+}
+
 /* implementation of ExecJustAssign(Inner|Outer|Scan)VarVirt */
 static pg_attribute_always_inline Datum
 ExecJustAssignVarVirtImpl(ExprState *state, TupleTableSlot *inslot, bool *isnull)
diff --git a/src/backend/executor/execTuples.c b/src/backend/executor/execTuples.c
index a7aa2ee02b..e5af9962b6 100644
--- a/src/backend/executor/execTuples.c
+++ b/src/backend/executor/execTuples.c
@@ -79,6 +79,9 @@ static inline void tts_buffer_heap_store_tuple(TupleTableSlot *slot,
 											   bool transfer_pin);
 static void tts_heap_store_tuple(TupleTableSlot *slot, HeapTuple tuple, bool shouldFree);
 
+static Bitmapset *cal_final_pre_detoast_attrs(Bitmapset *reference_attrs,
+											  TupleDesc tupleDesc,
+											  List *forbid_pre_detoast_vars);
 
 const TupleTableSlotOps TTSOpsVirtual;
 const TupleTableSlotOps TTSOpsHeapTuple;
@@ -176,6 +179,10 @@ tts_virtual_materialize(TupleTableSlot *slot)
 		if (att->attbyval || slot->tts_isnull[natt])
 			continue;
 
+		if (bitset_is_member(natt, slot->pre_detoasted_attrs))
+			/* it has been in slot->tts_mcxt already. */
+			continue;
+
 		val = slot->tts_values[natt];
 
 		if (att->attlen == -1 &&
@@ -392,6 +399,13 @@ tts_heap_materialize(TupleTableSlot *slot)
 	slot->tts_flags |= TTS_FLAG_SHOULDFREE;
 
 	MemoryContextSwitchTo(oldContext);
+
+	/*
+	 * tts_values is treated since tts_nvalid is set to 0, so let free the
+	 * pre-detoast datum.
+	 */
+	ExecFreePreDetoastDatum(slot);
+
 }
 
 static void
@@ -457,6 +471,9 @@ tts_heap_store_tuple(TupleTableSlot *slot, HeapTuple tuple, bool shouldFree)
 
 	if (shouldFree)
 		slot->tts_flags |= TTS_FLAG_SHOULDFREE;
+
+	/* slot_nvalid = 0 */
+	ExecFreePreDetoastDatum(slot);
 }
 
 
@@ -567,6 +584,12 @@ tts_minimal_materialize(TupleTableSlot *slot)
 	mslot->minhdr.t_data = (HeapTupleHeader) ((char *) mslot->mintuple - MINIMAL_TUPLE_OFFSET);
 
 	MemoryContextSwitchTo(oldContext);
+
+	/*
+	 * tts_values is treated as non valid (tts_nvalid = 0), free the
+	 * pre-detoast datum.
+	 */
+	ExecFreePreDetoastDatum(slot);
 }
 
 static void
@@ -637,6 +660,9 @@ tts_minimal_store_tuple(TupleTableSlot *slot, MinimalTuple mtup, bool shouldFree
 
 	if (shouldFree)
 		slot->tts_flags |= TTS_FLAG_SHOULDFREE;
+
+	/* tts_nvalid = 0 */
+	ExecFreePreDetoastDatum(slot);
 }
 
 
@@ -771,6 +797,12 @@ tts_buffer_heap_materialize(TupleTableSlot *slot)
 	slot->tts_flags |= TTS_FLAG_SHOULDFREE;
 
 	MemoryContextSwitchTo(oldContext);
+
+	/*
+	 * tts_nvalid = 0 means tts_values will be not reliable, so clear the
+	 * information about pre-detoast-datum.
+	 */
+	ExecFreePreDetoastDatum(slot);
 }
 
 static void
@@ -904,6 +936,9 @@ tts_buffer_heap_store_tuple(TupleTableSlot *slot, HeapTuple tuple,
 		 */
 		ReleaseBuffer(buffer);
 	}
+
+	/* tts_nvalid = 0 */
+	ExecFreePreDetoastDatum(slot);
 }
 
 /*
@@ -1150,7 +1185,10 @@ MakeTupleTableSlot(TupleDesc tupleDesc,
 			 + MAXALIGN(tupleDesc->natts * sizeof(Datum)));
 
 		PinTupleDesc(tupleDesc);
+		slot->pre_detoasted_attrs = bitset_init(tupleDesc->natts);
 	}
+	else
+		slot->pre_detoasted_attrs = NULL;
 
 	/*
 	 * And allow slot type specific initialization.
@@ -1304,6 +1342,10 @@ ExecSetSlotDescriptor(TupleTableSlot *slot, /* slot to change */
 		pfree(slot->tts_values);
 	if (slot->tts_isnull)
 		pfree(slot->tts_isnull);
+	if (slot->pre_detoasted_attrs)
+		bitset_free(slot->pre_detoasted_attrs);
+
+	slot->pre_detoasted_attrs = bitset_init(tupdesc->natts);
 
 	/*
 	 * Install the new descriptor; if it's refcounted, bump its refcount.
@@ -1810,12 +1852,26 @@ void
 ExecInitScanTupleSlot(EState *estate, ScanState *scanstate,
 					  TupleDesc tupledesc, const TupleTableSlotOps *tts_ops)
 {
+	Scan	   *splan = (Scan *) scanstate->ps.plan;
+
 	scanstate->ss_ScanTupleSlot = ExecAllocTableSlot(&estate->es_tupleTable,
 													 tupledesc, tts_ops);
 	scanstate->ps.scandesc = tupledesc;
 	scanstate->ps.scanopsfixed = tupledesc != NULL;
 	scanstate->ps.scanops = tts_ops;
 	scanstate->ps.scanopsset = true;
+
+	if (is_scan_plan((Plan *) splan))
+	{
+		/*
+		 * We may run detoast in Qual or Projection, but all of them happen at
+		 * the ss_ScanTupleSlot rather than ps_ResultTupleSlot. So we can only
+		 * take care of the ss_ScanTupleSlot.
+		 */
+		scanstate->scan_pre_detoast_attrs = cal_final_pre_detoast_attrs(splan->reference_attrs,
+																		tupledesc,
+																		splan->plan.forbid_pre_detoast_vars);
+	}
 }
 
 /* ----------------
@@ -2336,3 +2392,82 @@ end_tup_output(TupOutputState *tstate)
 	ExecDropSingleTupleTableSlot(tstate->slot);
 	pfree(tstate);
 }
+
+/*
+ * cal_final_pre_detoast_attrs
+ *		Calculate the final attributes which pre-detoast be helpful.
+ *
+ * reference_attrs: the attributes which will be detoast at this plan level.
+ * due to the implementation issue, some non-toast attribute may be included
+ * which should be filtered out with tupleDesc.
+ *
+ * forbid_pre_detoast_vars: the vars which should not be pre-detoast as the
+ * small_tlist reason.
+ */
+static Bitmapset *
+cal_final_pre_detoast_attrs(Bitmapset *reference_attrs,
+							TupleDesc tupleDesc,
+							List *forbid_pre_detoast_vars)
+{
+	Bitmapset  *final = NULL,
+			   *toast_attrs = NULL,
+			   *forbid_pre_detoast_attrs = NULL;
+
+	int			i;
+	ListCell   *lc;
+
+	if (bms_is_empty(reference_attrs))
+		return NULL;
+
+	/*
+	 * there is no exact data type in create_plan or set_plan_refs stage, so
+	 * reference_attrs may have some attribute which is not toast attrs at
+	 * all, which should be removed.
+	 */
+	for (i = 0; i < tupleDesc->natts; i++)
+	{
+		Form_pg_attribute attr = TupleDescAttr(tupleDesc, i);
+
+		if (attr->attlen == -1 && attr->attstorage != TYPSTORAGE_PLAIN)
+			toast_attrs = bms_add_member(toast_attrs, attr->attnum - 1);
+	}
+
+	final = bms_intersect(reference_attrs, toast_attrs);
+
+	/*
+	 * Due to the fact of detoast-datum will make the tuple bigger which is
+	 * bad for some nodes like Sort/Hash, to avoid performance regression,
+	 * such attribute should be removed as well.
+	 */
+	foreach(lc, forbid_pre_detoast_vars)
+	{
+		Var		   *var = lfirst_node(Var, lc);
+
+		forbid_pre_detoast_attrs = bms_add_member(forbid_pre_detoast_attrs, var->varattno - 1);
+	}
+
+	final = bms_del_members(final, forbid_pre_detoast_attrs);
+
+	bms_free(toast_attrs);
+	bms_free(forbid_pre_detoast_attrs);
+
+	return final;
+}
+
+
+void
+SetPredetoastAttrsForJoin(JoinState *j)
+{
+	PlanState  *outerstate = outerPlanState(j);
+	PlanState  *innerstate = innerPlanState(j);
+
+	j->outer_pre_detoast_attrs = cal_final_pre_detoast_attrs(
+															 ((Join *) j->ps.plan)->outer_reference_attrs,
+															 outerstate->ps_ResultTupleDesc,
+															 outerstate->plan->forbid_pre_detoast_vars);
+
+	j->inner_pre_detoast_attrs = cal_final_pre_detoast_attrs(
+															 ((Join *) j->ps.plan)->inner_reference_attrs,
+															 innerstate->ps_ResultTupleDesc,
+															 innerstate->plan->forbid_pre_detoast_vars);
+}
diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index cff5dc723e..a8646ded02 100644
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -572,6 +572,8 @@ ExecConditionalAssignProjectionInfo(PlanState *planstate, TupleDesc inputDesc,
 		planstate->resultopsset = planstate->scanopsset;
 		planstate->resultopsfixed = planstate->scanopsfixed;
 		planstate->resultops = planstate->scanops;
+
+		Assert(planstate->ps_ResultTupleDesc != NULL);
 	}
 	else
 	{
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 1cbec4647c..19a05ed624 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -756,6 +756,8 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	innerPlanState(hjstate) = ExecInitNode((Plan *) hashNode, estate, eflags);
 	innerDesc = ExecGetResultType(innerPlanState(hjstate));
 
+	SetPredetoastAttrsForJoin((JoinState *) hjstate);
+
 	/*
 	 * Initialize result slot, type and projection.
 	 */
diff --git a/src/backend/executor/nodeMergejoin.c b/src/backend/executor/nodeMergejoin.c
index c1a8ca2464..be7cbd7f30 100644
--- a/src/backend/executor/nodeMergejoin.c
+++ b/src/backend/executor/nodeMergejoin.c
@@ -1497,6 +1497,8 @@ ExecInitMergeJoin(MergeJoin *node, EState *estate, int eflags)
 											  (eflags | EXEC_FLAG_MARK));
 	innerDesc = ExecGetResultType(innerPlanState(mergestate));
 
+	SetPredetoastAttrsForJoin((JoinState *) mergestate);
+
 	/*
 	 * For certain types of inner child nodes, it is advantageous to issue
 	 * MARK every time we advance past an inner tuple we will never return to.
diff --git a/src/backend/executor/nodeNestloop.c b/src/backend/executor/nodeNestloop.c
index 06fa0a9b31..2d40d19192 100644
--- a/src/backend/executor/nodeNestloop.c
+++ b/src/backend/executor/nodeNestloop.c
@@ -306,6 +306,7 @@ ExecInitNestLoop(NestLoop *node, EState *estate, int eflags)
 	 */
 	ExecInitResultTupleSlotTL(&nlstate->js.ps, &TTSOpsVirtual);
 	ExecAssignProjectionInfo(&nlstate->js.ps, NULL);
+	SetPredetoastAttrsForJoin((JoinState *) nlstate);
 
 	/*
 	 * initialize child expressions
diff --git a/src/backend/jit/llvm/llvmjit_expr.c b/src/backend/jit/llvm/llvmjit_expr.c
index 33161d812f..56c10c9e4d 100644
--- a/src/backend/jit/llvm/llvmjit_expr.c
+++ b/src/backend/jit/llvm/llvmjit_expr.c
@@ -396,30 +396,52 @@ llvm_compile_expr(ExprState *state)
 			case EEOP_INNER_VAR:
 			case EEOP_OUTER_VAR:
 			case EEOP_SCAN_VAR:
+			case EEOP_INNER_VAR_TOAST:
+			case EEOP_OUTER_VAR_TOAST:
+			case EEOP_SCAN_VAR_TOAST:
 				{
 					LLVMValueRef value,
 								isnull;
 					LLVMValueRef v_attnum;
 					LLVMValueRef v_values;
 					LLVMValueRef v_nulls;
+					LLVMValueRef v_slot;
 
-					if (opcode == EEOP_INNER_VAR)
+					if (opcode == EEOP_INNER_VAR || opcode == EEOP_INNER_VAR_TOAST)
 					{
+						v_slot = v_innerslot;
 						v_values = v_innervalues;
 						v_nulls = v_innernulls;
 					}
-					else if (opcode == EEOP_OUTER_VAR)
+					else if (opcode == EEOP_OUTER_VAR || opcode == EEOP_OUTER_VAR_TOAST)
 					{
+						v_slot = v_outerslot;
 						v_values = v_outervalues;
 						v_nulls = v_outernulls;
 					}
 					else
 					{
+						v_slot = v_scanslot;
 						v_values = v_scanvalues;
 						v_nulls = v_scannulls;
 					}
 
 					v_attnum = l_int32_const(lc, op->d.var.attnum);
+
+					if (opcode == EEOP_INNER_VAR_TOAST ||
+						opcode == EEOP_OUTER_VAR_TOAST ||
+						opcode == EEOP_SCAN_VAR_TOAST)
+					{
+						LLVMValueRef params[2];
+
+						params[0] = v_slot;
+						params[1] = l_int32_const(lc, op->d.var.attnum);
+						l_call(b,
+							   llvm_pg_var_func_type("ExecSlotDetoastDatumExternal"),
+							   llvm_pg_func(mod, "ExecSlotDetoastDatumExternal"),
+							   params, lengthof(params), "");
+					}
+
 					value = l_load_gep1(b, TypeSizeT, v_values, v_attnum, "");
 					isnull = l_load_gep1(b, TypeStorageBool, v_nulls, v_attnum, "");
 					LLVMBuildStore(b, value, v_resvaluep);
diff --git a/src/backend/jit/llvm/llvmjit_types.c b/src/backend/jit/llvm/llvmjit_types.c
index 5212f529c8..11a11028b8 100644
--- a/src/backend/jit/llvm/llvmjit_types.c
+++ b/src/backend/jit/llvm/llvmjit_types.c
@@ -177,4 +177,5 @@ void	   *referenced_functions[] =
 	strlen,
 	varsize_any,
 	ExecInterpExprStillValid,
+	ExecSlotDetoastDatumExternal,
 };
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index ca619eab94..69f5e72c43 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -314,7 +314,8 @@ static ModifyTable *make_modifytable(PlannerInfo *root, Plan *subplan,
 									 List *mergeActionLists, int epqParam);
 static GatherMerge *create_gather_merge_plan(PlannerInfo *root,
 											 GatherMergePath *best_path);
-
+static void set_plan_forbid_pre_detoast_vars_recurse(Plan *plan,
+													 List *recheck_list);
 
 /*
  * create_plan
@@ -346,6 +347,12 @@ create_plan(PlannerInfo *root, Path *best_path)
 	/* Recursively process the path tree, demanding the correct tlist result */
 	plan = create_plan_recurse(root, best_path, CP_EXACT_TLIST);
 
+	/*
+	 * After the plan tree is built completed, we start to walk for which
+	 * expressions should not used the shared-detoast feature.
+	 */
+	set_plan_forbid_pre_detoast_vars_recurse(plan, NIL);
+
 	/*
 	 * Make sure the topmost plan node's targetlist exposes the original
 	 * column names and other decorative info.  Targetlists generated within
@@ -378,6 +385,89 @@ create_plan(PlannerInfo *root, Path *best_path)
 	return plan;
 }
 
+/*
+ * set_plan_not_pre_detoast_vars
+ *
+ *	set the toast_attrs according recheck_list.
+ *
+ * recheck_list = NIL means we need to do thing.
+ */
+static void
+set_plan_not_pre_detoast_vars(Plan *plan, List *recheck_list)
+{
+	ListCell   *lc;
+	Var		   *var;
+
+	/*
+	 * fast path, if we don't have a recheck_list, the var in targetlist is
+	 * impossible member of it. and this case might be a pretty common case.
+	 */
+	if (recheck_list == NIL)
+		return;
+
+	foreach(lc, plan->targetlist)
+	{
+		TargetEntry *te = lfirst_node(TargetEntry, lc);
+
+		if (!IsA(te->expr, Var))
+			continue;
+		var = castNode(Var, te->expr);
+		if (var->varattno <= 0)
+			continue;
+		if (list_member(recheck_list, var))
+			/* pass the recheck */
+			plan->forbid_pre_detoast_vars = lappend(plan->forbid_pre_detoast_vars, var);
+	}
+}
+
+
+/*
+ * set_plan_forbid_pre_detoast_vars_recurse
+ *		Walking the Plan tree to gather the vars which should be as small
+ * as possible, hence all of them should not using shared detoast datum
+ * feature.
+ */
+static void
+set_plan_forbid_pre_detoast_vars_recurse(Plan *plan, List *recheck_list)
+{
+	if (plan == NULL)
+		return;
+
+	set_plan_not_pre_detoast_vars(plan, recheck_list);
+
+	if (IsA(plan, Sort) || IsA(plan, Memoize) || IsA(plan, WindowAgg) ||
+		IsA(plan, Hash) || IsA(plan, Material) || IsA(plan, IncrementalSort))
+	{
+		List	   *subplan_exprs = get_tlist_exprs(plan->lefttree->targetlist, true);
+
+		/*
+		 * for the sort-like nodes, we want the subplan's output(only) as
+		 * small as possible, but the subplan's other expressions like Qual
+		 * doesn't have this restriction since they are not output to the
+		 * upper nodes. so we set the recheck_list to the subplan->targetlist.
+		 */
+		set_plan_forbid_pre_detoast_vars_recurse(plan->lefttree, subplan_exprs);
+	}
+	else if (IsA(plan, HashJoin) && castNode(HashJoin, plan)->left_small_tlist)
+	{
+		List	   *subplan_exprs = get_tlist_exprs(plan->lefttree->targetlist, true);
+
+		/*
+		 * If the left_small_tlist wants a as small as possible tlist, set it
+		 * in a way like sort.
+		 */
+		set_plan_forbid_pre_detoast_vars_recurse(plan->lefttree, subplan_exprs);
+		/* The righttree is a Hash node, it can be set with its own rule */
+		set_plan_forbid_pre_detoast_vars_recurse(plan->righttree, plan->forbid_pre_detoast_vars);
+	}
+	else
+	{
+		/* just push down the forbid_pre_detoast_vars from its children. */
+		set_plan_forbid_pre_detoast_vars_recurse(plan->lefttree, plan->forbid_pre_detoast_vars);
+		set_plan_forbid_pre_detoast_vars_recurse(plan->righttree, plan->forbid_pre_detoast_vars);
+	}
+}
+
 /*
  * create_plan_recurse
  *	  Recursive guts of create_plan().
@@ -4884,6 +4974,8 @@ create_hashjoin_plan(PlannerInfo *root,
 
 	copy_generic_path_info(&join_plan->join.plan, &best_path->jpath.path);
 
+	join_plan->left_small_tlist = (best_path->num_batches > 1);
+
 	return join_plan;
 }
 
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 22a1fa29f3..d11177d688 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -27,6 +27,7 @@
 #include "optimizer/tlist.h"
 #include "parser/parse_relation.h"
 #include "tcop/utility.h"
+#include "utils/fmgroids.h"
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
 
@@ -55,11 +56,27 @@ typedef struct
 	tlist_vinfo vars[FLEXIBLE_ARRAY_MEMBER];	/* has num_vars entries */
 } indexed_tlist;
 
+typedef struct
+{
+	/* var is added into existing_attrs for the first time. */
+	Bitmapset  *existing_attrs;
+	/* following add to the final_ref_attrs. */
+	Bitmapset **final_ref_attrs;
+} intermediate_var_ref_context;
+
+typedef struct
+{
+	int			level_added;
+	int			level;
+} intermediate_level_context;
+
 typedef struct
 {
 	PlannerInfo *root;
 	int			rtoffset;
 	double		num_exec;
+	intermediate_level_context level_ctx;
+	intermediate_var_ref_context scan_reference_attrs;
 } fix_scan_expr_context;
 
 typedef struct
@@ -71,6 +88,9 @@ typedef struct
 	int			rtoffset;
 	NullingRelsMatch nrm_match;
 	double		num_exec;
+	intermediate_level_context level_ctx;
+	intermediate_var_ref_context outer_reference_attrs;
+	intermediate_var_ref_context inner_reference_attrs;
 } fix_join_expr_context;
 
 typedef struct
@@ -127,8 +147,8 @@ typedef struct
 	(((con)->consttype == REGCLASSOID || (con)->consttype == OIDOID) && \
 	 !(con)->constisnull)
 
-#define fix_scan_list(root, lst, rtoffset, num_exec) \
-	((List *) fix_scan_expr(root, (Node *) (lst), rtoffset, num_exec))
+#define fix_scan_list(root, lst, rtoffset, num_exec, pre_detoast_attrs) \
+	((List *) fix_scan_expr(root, (Node *) (lst), rtoffset, num_exec, pre_detoast_attrs))
 
 static void add_rtes_to_flat_rtable(PlannerInfo *root, bool recursing);
 static void flatten_unplanned_rtes(PlannerGlobal *glob, RangeTblEntry *rte);
@@ -158,7 +178,8 @@ static Plan *set_mergeappend_references(PlannerInfo *root,
 static void set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset);
 static Relids offset_relid_set(Relids relids, int rtoffset);
 static Node *fix_scan_expr(PlannerInfo *root, Node *node,
-						   int rtoffset, double num_exec);
+						   int rtoffset, double num_exec,
+						   Bitmapset **scan_reference_attrs);
 static Node *fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context);
 static bool fix_scan_expr_walker(Node *node, fix_scan_expr_context *context);
 static void set_join_references(PlannerInfo *root, Join *join, int rtoffset);
@@ -190,7 +211,10 @@ static List *fix_join_expr(PlannerInfo *root,
 						   Index acceptable_rel,
 						   int rtoffset,
 						   NullingRelsMatch nrm_match,
-						   double num_exec);
+						   double num_exec,
+						   Bitmapset **outer_reference_attrs,
+						   Bitmapset **inner_reference_attrs);
+
 static Node *fix_join_expr_mutator(Node *node,
 								   fix_join_expr_context *context);
 static Node *fix_upper_expr(PlannerInfo *root,
@@ -628,10 +652,16 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
+
+				splan->scan.plan.forbid_pre_detoast_vars =
+					fix_scan_list(root, splan->scan.plan.forbid_pre_detoast_vars,
+								  rtoffset, NUM_EXEC_TLIST(plan), NULL);
 			}
 			break;
 		case T_SampleScan:
@@ -641,13 +671,20 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs
+					);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
 				splan->tablesample = (TableSampleClause *)
 					fix_scan_expr(root, (Node *) splan->tablesample,
-								  rtoffset, 1);
+								  rtoffset, 1,
+								  &splan->scan.reference_attrs);
+				splan->scan.plan.forbid_pre_detoast_vars =
+					fix_scan_list(root, splan->scan.plan.forbid_pre_detoast_vars,
+								  rtoffset, NUM_EXEC_TLIST(plan), NULL);
 			}
 			break;
 		case T_IndexScan:
@@ -657,28 +694,40 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
+
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
+
 				splan->indexqual =
 					fix_scan_list(root, splan->indexqual,
-								  rtoffset, 1);
+								  rtoffset, 1, &splan->scan.reference_attrs);
 				splan->indexqualorig =
 					fix_scan_list(root, splan->indexqualorig,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
 				splan->indexorderby =
 					fix_scan_list(root, splan->indexorderby,
-								  rtoffset, 1);
+								  rtoffset, 1, &splan->scan.reference_attrs);
 				splan->indexorderbyorig =
 					fix_scan_list(root, splan->indexorderbyorig,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan), &splan->scan.reference_attrs);
+				splan->scan.plan.forbid_pre_detoast_vars =
+					fix_scan_list(root, splan->scan.plan.forbid_pre_detoast_vars,
+								  rtoffset, NUM_EXEC_TLIST(plan), NULL);
 			}
 			break;
 		case T_IndexOnlyScan:
 			{
 				IndexOnlyScan *splan = (IndexOnlyScan *) plan;
 
+				splan->scan.plan.forbid_pre_detoast_vars =
+					fix_scan_list(root, splan->scan.plan.forbid_pre_detoast_vars,
+								  rtoffset, NUM_EXEC_TLIST(plan), NULL);
+
 				return set_indexonlyscan_references(root, splan, rtoffset);
 			}
 			break;
@@ -691,10 +740,15 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				Assert(splan->scan.plan.targetlist == NIL);
 				Assert(splan->scan.plan.qual == NIL);
 				splan->indexqual =
-					fix_scan_list(root, splan->indexqual, rtoffset, 1);
+					fix_scan_list(root, splan->indexqual, rtoffset, 1,
+								  &splan->scan.reference_attrs);
 				splan->indexqualorig =
 					fix_scan_list(root, splan->indexqualorig,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
+				splan->scan.plan.forbid_pre_detoast_vars =
+					fix_scan_list(root, splan->scan.plan.forbid_pre_detoast_vars,
+								  rtoffset, NUM_EXEC_TLIST(plan), NULL);
 			}
 			break;
 		case T_BitmapHeapScan:
@@ -704,13 +758,20 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
 				splan->bitmapqualorig =
 					fix_scan_list(root, splan->bitmapqualorig,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
+				splan->scan.plan.forbid_pre_detoast_vars =
+					fix_scan_list(root, splan->scan.plan.forbid_pre_detoast_vars,
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  NULL);
 			}
 			break;
 		case T_TidScan:
@@ -720,13 +781,20 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
 				splan->tidquals =
 					fix_scan_list(root, splan->tidquals,
-								  rtoffset, 1);
+								  rtoffset, 1,
+								  &splan->scan.reference_attrs);
+				splan->scan.plan.forbid_pre_detoast_vars =
+					fix_scan_list(root, splan->scan.plan.forbid_pre_detoast_vars,
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  NULL);
 			}
 			break;
 		case T_TidRangeScan:
@@ -736,13 +804,20 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
 				splan->tidrangequals =
 					fix_scan_list(root, splan->tidrangequals,
-								  rtoffset, 1);
+								  rtoffset, 1,
+								  &splan->scan.reference_attrs);
+				splan->scan.plan.forbid_pre_detoast_vars =
+					fix_scan_list(root, splan->scan.plan.forbid_pre_detoast_vars,
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  NULL);
 			}
 			break;
 		case T_SubqueryScan:
@@ -757,12 +832,16 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
 				splan->functions =
-					fix_scan_list(root, splan->functions, rtoffset, 1);
+					fix_scan_list(root, splan->functions, rtoffset, 1,
+								  &splan->scan.reference_attrs);
+
 			}
 			break;
 		case T_TableFuncScan:
@@ -772,13 +851,17 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
+
 				splan->tablefunc = (TableFunc *)
 					fix_scan_expr(root, (Node *) splan->tablefunc,
-								  rtoffset, 1);
+								  rtoffset, 1,
+								  &splan->scan.reference_attrs);
 			}
 			break;
 		case T_ValuesScan:
@@ -788,13 +871,16 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
 				splan->values_lists =
 					fix_scan_list(root, splan->values_lists,
-								  rtoffset, 1);
+								  rtoffset, 1,
+								  &splan->scan.reference_attrs);
 			}
 			break;
 		case T_CteScan:
@@ -804,10 +890,16 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
+				splan->scan.plan.forbid_pre_detoast_vars =
+					fix_scan_list(root, splan->scan.plan.forbid_pre_detoast_vars,
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  NULL);
 			}
 			break;
 		case T_NamedTuplestoreScan:
@@ -817,10 +909,12 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
 			}
 			break;
 		case T_WorkTableScan:
@@ -830,10 +924,12 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				splan->scan.scanrelid += rtoffset;
 				splan->scan.plan.targetlist =
 					fix_scan_list(root, splan->scan.plan.targetlist,
-								  rtoffset, NUM_EXEC_TLIST(plan));
+								  rtoffset, NUM_EXEC_TLIST(plan),
+								  &splan->scan.reference_attrs);
 				splan->scan.plan.qual =
 					fix_scan_list(root, splan->scan.plan.qual,
-								  rtoffset, NUM_EXEC_QUAL(plan));
+								  rtoffset, NUM_EXEC_QUAL(plan),
+								  &splan->scan.reference_attrs);
 			}
 			break;
 		case T_ForeignScan:
@@ -873,7 +969,8 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 
 				mplan->param_exprs = fix_scan_list(root, mplan->param_exprs,
 												   rtoffset,
-												   NUM_EXEC_TLIST(plan));
+												   NUM_EXEC_TLIST(plan),
+												   NULL);
 				break;
 			}
 
@@ -933,9 +1030,9 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				Assert(splan->plan.qual == NIL);
 
 				splan->limitOffset =
-					fix_scan_expr(root, splan->limitOffset, rtoffset, 1);
+					fix_scan_expr(root, splan->limitOffset, rtoffset, 1, NULL);
 				splan->limitCount =
-					fix_scan_expr(root, splan->limitCount, rtoffset, 1);
+					fix_scan_expr(root, splan->limitCount, rtoffset, 1, NULL);
 			}
 			break;
 		case T_Agg:
@@ -988,17 +1085,17 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				 * variable refs, so fix_scan_expr works for them.
 				 */
 				wplan->startOffset =
-					fix_scan_expr(root, wplan->startOffset, rtoffset, 1);
+					fix_scan_expr(root, wplan->startOffset, rtoffset, 1, NULL);
 				wplan->endOffset =
-					fix_scan_expr(root, wplan->endOffset, rtoffset, 1);
+					fix_scan_expr(root, wplan->endOffset, rtoffset, 1, NULL);
 				wplan->runCondition = fix_scan_list(root,
 													wplan->runCondition,
 													rtoffset,
-													NUM_EXEC_TLIST(plan));
+													NUM_EXEC_TLIST(plan), NULL);
 				wplan->runConditionOrig = fix_scan_list(root,
 														wplan->runConditionOrig,
 														rtoffset,
-														NUM_EXEC_TLIST(plan));
+														NUM_EXEC_TLIST(plan), NULL);
 			}
 			break;
 		case T_Result:
@@ -1038,14 +1135,14 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 
 					splan->plan.targetlist =
 						fix_scan_list(root, splan->plan.targetlist,
-									  rtoffset, NUM_EXEC_TLIST(plan));
+									  rtoffset, NUM_EXEC_TLIST(plan), NULL);
 					splan->plan.qual =
 						fix_scan_list(root, splan->plan.qual,
-									  rtoffset, NUM_EXEC_QUAL(plan));
+									  rtoffset, NUM_EXEC_QUAL(plan), NULL);
 				}
 				/* resconstantqual can't contain any subplan variable refs */
 				splan->resconstantqual =
-					fix_scan_expr(root, splan->resconstantqual, rtoffset, 1);
+					fix_scan_expr(root, splan->resconstantqual, rtoffset, 1, NULL);
 			}
 			break;
 		case T_ProjectSet:
@@ -1061,7 +1158,7 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 
 				splan->withCheckOptionLists =
 					fix_scan_list(root, splan->withCheckOptionLists,
-								  rtoffset, 1);
+								  rtoffset, 1, NULL);
 
 				if (splan->returningLists)
 				{
@@ -1118,18 +1215,20 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 						fix_join_expr(root, splan->onConflictSet,
 									  NULL, itlist,
 									  linitial_int(splan->resultRelations),
-									  rtoffset, NRM_EQUAL, NUM_EXEC_QUAL(plan));
+									  rtoffset, NRM_EQUAL, NUM_EXEC_QUAL(plan),
+									  NULL, NULL);
 
 					splan->onConflictWhere = (Node *)
 						fix_join_expr(root, (List *) splan->onConflictWhere,
 									  NULL, itlist,
 									  linitial_int(splan->resultRelations),
-									  rtoffset, NRM_EQUAL, NUM_EXEC_QUAL(plan));
+									  rtoffset, NRM_EQUAL, NUM_EXEC_QUAL(plan),
+									  NULL, NULL);
 
 					pfree(itlist);
 
 					splan->exclRelTlist =
-						fix_scan_list(root, splan->exclRelTlist, rtoffset, 1);
+						fix_scan_list(root, splan->exclRelTlist, rtoffset, 1, NULL);
 				}
 
 				/*
@@ -1182,7 +1281,8 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 															   resultrel,
 															   rtoffset,
 															   NRM_EQUAL,
-															   NUM_EXEC_TLIST(plan));
+															   NUM_EXEC_TLIST(plan),
+															   NULL, NULL);
 
 							/* Fix quals too. */
 							action->qual = (Node *) fix_join_expr(root,
@@ -1191,7 +1291,8 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 																  resultrel,
 																  rtoffset,
 																  NRM_EQUAL,
-																  NUM_EXEC_QUAL(plan));
+																  NUM_EXEC_QUAL(plan),
+																  NULL, NULL);
 						}
 					}
 				}
@@ -1356,13 +1457,16 @@ set_indexonlyscan_references(PlannerInfo *root,
 					   NUM_EXEC_QUAL((Plan *) plan));
 	/* indexqual is already transformed to reference index columns */
 	plan->indexqual = fix_scan_list(root, plan->indexqual,
-									rtoffset, 1);
+									rtoffset, 1,
+									&plan->scan.reference_attrs);
 	/* indexorderby is already transformed to reference index columns */
 	plan->indexorderby = fix_scan_list(root, plan->indexorderby,
-									   rtoffset, 1);
+									   rtoffset, 1,
+									   &plan->scan.reference_attrs);
 	/* indextlist must NOT be transformed to reference index columns */
 	plan->indextlist = fix_scan_list(root, plan->indextlist,
-									 rtoffset, NUM_EXEC_TLIST((Plan *) plan));
+									 rtoffset, NUM_EXEC_TLIST((Plan *) plan),
+									 &plan->scan.reference_attrs);
 
 	pfree(index_itlist);
 
@@ -1409,10 +1513,10 @@ set_subqueryscan_references(PlannerInfo *root,
 		plan->scan.scanrelid += rtoffset;
 		plan->scan.plan.targetlist =
 			fix_scan_list(root, plan->scan.plan.targetlist,
-						  rtoffset, NUM_EXEC_TLIST((Plan *) plan));
+						  rtoffset, NUM_EXEC_TLIST((Plan *) plan), NULL);
 		plan->scan.plan.qual =
 			fix_scan_list(root, plan->scan.plan.qual,
-						  rtoffset, NUM_EXEC_QUAL((Plan *) plan));
+						  rtoffset, NUM_EXEC_QUAL((Plan *) plan), NULL);
 
 		result = (Plan *) plan;
 	}
@@ -1612,7 +1716,7 @@ set_foreignscan_references(PlannerInfo *root,
 		/* fdw_scan_tlist itself just needs fix_scan_list() adjustments */
 		fscan->fdw_scan_tlist =
 			fix_scan_list(root, fscan->fdw_scan_tlist,
-						  rtoffset, NUM_EXEC_TLIST((Plan *) fscan));
+						  rtoffset, NUM_EXEC_TLIST((Plan *) fscan), NULL);
 	}
 	else
 	{
@@ -1622,16 +1726,16 @@ set_foreignscan_references(PlannerInfo *root,
 		 */
 		fscan->scan.plan.targetlist =
 			fix_scan_list(root, fscan->scan.plan.targetlist,
-						  rtoffset, NUM_EXEC_TLIST((Plan *) fscan));
+						  rtoffset, NUM_EXEC_TLIST((Plan *) fscan), NULL);
 		fscan->scan.plan.qual =
 			fix_scan_list(root, fscan->scan.plan.qual,
-						  rtoffset, NUM_EXEC_QUAL((Plan *) fscan));
+						  rtoffset, NUM_EXEC_QUAL((Plan *) fscan), NULL);
 		fscan->fdw_exprs =
 			fix_scan_list(root, fscan->fdw_exprs,
-						  rtoffset, NUM_EXEC_QUAL((Plan *) fscan));
+						  rtoffset, NUM_EXEC_QUAL((Plan *) fscan), NULL);
 		fscan->fdw_recheck_quals =
 			fix_scan_list(root, fscan->fdw_recheck_quals,
-						  rtoffset, NUM_EXEC_QUAL((Plan *) fscan));
+						  rtoffset, NUM_EXEC_QUAL((Plan *) fscan), NULL);
 	}
 
 	fscan->fs_relids = offset_relid_set(fscan->fs_relids, rtoffset);
@@ -1690,20 +1794,20 @@ set_customscan_references(PlannerInfo *root,
 		/* custom_scan_tlist itself just needs fix_scan_list() adjustments */
 		cscan->custom_scan_tlist =
 			fix_scan_list(root, cscan->custom_scan_tlist,
-						  rtoffset, NUM_EXEC_TLIST((Plan *) cscan));
+						  rtoffset, NUM_EXEC_TLIST((Plan *) cscan), NULL);
 	}
 	else
 	{
 		/* Adjust tlist, qual, custom_exprs in the standard way */
 		cscan->scan.plan.targetlist =
 			fix_scan_list(root, cscan->scan.plan.targetlist,
-						  rtoffset, NUM_EXEC_TLIST((Plan *) cscan));
+						  rtoffset, NUM_EXEC_TLIST((Plan *) cscan), NULL);
 		cscan->scan.plan.qual =
 			fix_scan_list(root, cscan->scan.plan.qual,
-						  rtoffset, NUM_EXEC_QUAL((Plan *) cscan));
+						  rtoffset, NUM_EXEC_QUAL((Plan *) cscan), NULL);
 		cscan->custom_exprs =
 			fix_scan_list(root, cscan->custom_exprs,
-						  rtoffset, NUM_EXEC_QUAL((Plan *) cscan));
+						  rtoffset, NUM_EXEC_QUAL((Plan *) cscan), NULL);
 	}
 
 	/* Adjust child plan-nodes recursively, if needed */
@@ -2111,6 +2215,95 @@ fix_alternative_subplan(PlannerInfo *root, AlternativeSubPlan *asplan,
 	return (Node *) bestplan;
 }
 
+
+static inline void
+setup_intermediate_level_ctx(intermediate_level_context *ctx)
+{
+	ctx->level = 0;
+	ctx->level_added = false;
+}
+
+static inline void
+setup_intermediate_var_ref_ctx(intermediate_var_ref_context *ctx, Bitmapset **final_ref_attrs)
+{
+	ctx->existing_attrs = NULL;
+	ctx->final_ref_attrs = final_ref_attrs;
+}
+
+/*
+ * increase_level_for_pre_detoast
+ *	Check if the given Expr could detoast a Var directly, if yes,
+ * increase the level and return true. otherwise return false;
+ */
+static inline void
+increase_level_for_pre_detoast(Node *node, intermediate_level_context *ctx)
+{
+	/* The following nodes is impossible to detoast a Var directly. */
+	if (IsA(node, List) || IsA(node, TargetEntry) || IsA(node, NullTest))
+	{
+		ctx->level_added = false;
+	}
+	else if (IsA(node, FuncExpr) && castNode(FuncExpr, node)->funcid == F_PG_COLUMN_COMPRESSION)
+	{
+		/* let's not detoast first so that pg_column_compression works. */
+		ctx->level_added = false;
+	}
+	else
+	{
+		ctx->level_added = true;
+		ctx->level += 1;
+	}
+}
+
+static inline void
+decreased_level_for_pre_detoast(intermediate_level_context *ctx)
+{
+	if (ctx->level_added)
+		ctx->level -= 1;
+
+	ctx->level_added = false;
+}
+
+/*
+ * add_pre_detoast_vars
+ *		add the var's information into pre_detoast_attrs when the check is pass.
+ */
+static inline void
+add_pre_detoast_vars(intermediate_level_context *level_ctx,
+					 intermediate_var_ref_context *ctx,
+					 Var *var)
+{
+	int			attno;
+
+	if (level_ctx->level <= 1 || ctx->final_ref_attrs == NULL || var->varattno <= 0)
+		return;
+
+	attno = var->varattno - 1;
+	if (bms_is_member(attno, ctx->existing_attrs))
+	{
+		/* not the first time to access it, add it to final result. */
+		*ctx->final_ref_attrs = bms_add_member(*ctx->final_ref_attrs, attno);
+	}
+	else
+	{
+		/* first time. */
+		ctx->existing_attrs = bms_add_member(ctx->existing_attrs, attno);
+
+		/*
+		 * XXX:
+		 *
+		 * The above strategy doesn't help to detect if a Var is detoast
+		 * twice. Reasons are: 1. the context is not maintain in Plan node
+		 * level. so if it is detoast at targetlist and qual, we can't detect
+		 * it. 2. even we can make it at plan node, it still doesn't help for
+		 * the among-nodes case.
+		 *
+		 * So for now, I just disable it.
+		 */
+		*ctx->final_ref_attrs = bms_add_member(*ctx->final_ref_attrs, attno);
+	}
+}
+
 /*
  * fix_scan_expr
  *		Do set_plan_references processing on a scan-level expression
@@ -2130,13 +2323,16 @@ fix_alternative_subplan(PlannerInfo *root, AlternativeSubPlan *asplan,
  * if that seems safe.
  */
 static Node *
-fix_scan_expr(PlannerInfo *root, Node *node, int rtoffset, double num_exec)
+fix_scan_expr(PlannerInfo *root, Node *node, int rtoffset,
+			  double num_exec, Bitmapset **scan_reference_attrs)
 {
 	fix_scan_expr_context context;
 
 	context.root = root;
 	context.rtoffset = rtoffset;
 	context.num_exec = num_exec;
+	setup_intermediate_level_ctx(&context.level_ctx);
+	setup_intermediate_var_ref_ctx(&context.scan_reference_attrs, scan_reference_attrs);
 
 	if (rtoffset != 0 ||
 		root->multiexpr_params != NIL ||
@@ -2167,8 +2363,13 @@ fix_scan_expr(PlannerInfo *root, Node *node, int rtoffset, double num_exec)
 static Node *
 fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context)
 {
+	Node	   *n;
+
 	if (node == NULL)
 		return NULL;
+
+	increase_level_for_pre_detoast(node, &context->level_ctx);
+
 	if (IsA(node, Var))
 	{
 		Var		   *var = copyVar((Var *) node);
@@ -2186,10 +2387,16 @@ fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context)
 			var->varno += context->rtoffset;
 		if (var->varnosyn > 0)
 			var->varnosyn += context->rtoffset;
+
+		add_pre_detoast_vars(&context->level_ctx, &context->scan_reference_attrs, var);
+		decreased_level_for_pre_detoast(&context->level_ctx);
 		return (Node *) var;
 	}
 	if (IsA(node, Param))
+	{
+		decreased_level_for_pre_detoast(&context->level_ctx);
 		return fix_param_node(context->root, (Param *) node);
+	}
 	if (IsA(node, Aggref))
 	{
 		Aggref	   *aggref = (Aggref *) node;
@@ -2199,8 +2406,10 @@ fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context)
 		aggparam = find_minmax_agg_replacement_param(context->root, aggref);
 		if (aggparam != NULL)
 		{
+			decreased_level_for_pre_detoast(&context->level_ctx);
 			/* Make a copy of the Param for paranoia's sake */
 			return (Node *) copyObject(aggparam);
+
 		}
 		/* If no match, just fall through to process it normally */
 	}
@@ -2210,6 +2419,7 @@ fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context)
 
 		Assert(!IS_SPECIAL_VARNO(cexpr->cvarno));
 		cexpr->cvarno += context->rtoffset;
+		decreased_level_for_pre_detoast(&context->level_ctx);
 		return (Node *) cexpr;
 	}
 	if (IsA(node, PlaceHolderVar))
@@ -2218,29 +2428,52 @@ fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context)
 		PlaceHolderVar *phv = (PlaceHolderVar *) node;
 
 		/* XXX can we assert something about phnullingrels? */
-		return fix_scan_expr_mutator((Node *) phv->phexpr, context);
+		Node	   *n2 = fix_scan_expr_mutator((Node *) phv->phexpr, context);
+
+		decreased_level_for_pre_detoast(&context->level_ctx);
+		return n2;
 	}
 	if (IsA(node, AlternativeSubPlan))
-		return fix_scan_expr_mutator(fix_alternative_subplan(context->root,
-															 (AlternativeSubPlan *) node,
-															 context->num_exec),
-									 context);
+	{
+		Node	   *n2 = fix_scan_expr_mutator(fix_alternative_subplan(context->root,
+																	   (AlternativeSubPlan *) node,
+																	   context->num_exec),
+											   context);
+
+		decreased_level_for_pre_detoast(&context->level_ctx);
+		return n2;
+	}
 	fix_expr_common(context->root, node);
-	return expression_tree_mutator(node, fix_scan_expr_mutator,
-								   (void *) context);
+	n = expression_tree_mutator(node, fix_scan_expr_mutator, (void *) context);
+	decreased_level_for_pre_detoast(&context->level_ctx);
+	return n;
 }
 
 static bool
 fix_scan_expr_walker(Node *node, fix_scan_expr_context *context)
 {
+	bool		ret;
+
 	if (node == NULL)
 		return false;
+
+	increase_level_for_pre_detoast(node, &context->level_ctx);
+
+	if (IsA(node, Var))
+	{
+		add_pre_detoast_vars(&context->level_ctx,
+							 &context->scan_reference_attrs,
+							 castNode(Var, node));
+	}
 	Assert(!(IsA(node, Var) && ((Var *) node)->varno == ROWID_VAR));
 	Assert(!IsA(node, PlaceHolderVar));
 	Assert(!IsA(node, AlternativeSubPlan));
 	fix_expr_common(context->root, node);
-	return expression_tree_walker(node, fix_scan_expr_walker,
-								  (void *) context);
+	ret = expression_tree_walker(node, fix_scan_expr_walker,
+								 (void *) context);
+
+	decreased_level_for_pre_detoast(&context->level_ctx);
+	return ret;
 }
 
 /*
@@ -2276,7 +2509,10 @@ set_join_references(PlannerInfo *root, Join *join, int rtoffset)
 								   (Index) 0,
 								   rtoffset,
 								   NRM_EQUAL,
-								   NUM_EXEC_QUAL((Plan *) join));
+								   NUM_EXEC_QUAL((Plan *) join),
+								   &join->outer_reference_attrs,
+								   &join->inner_reference_attrs
+		);
 
 	/* Now do join-type-specific stuff */
 	if (IsA(join, NestLoop))
@@ -2323,7 +2559,9 @@ set_join_references(PlannerInfo *root, Join *join, int rtoffset)
 										 (Index) 0,
 										 rtoffset,
 										 NRM_EQUAL,
-										 NUM_EXEC_QUAL((Plan *) join));
+										 NUM_EXEC_QUAL((Plan *) join),
+										 &join->outer_reference_attrs,
+										 &join->inner_reference_attrs);
 	}
 	else if (IsA(join, HashJoin))
 	{
@@ -2336,7 +2574,9 @@ set_join_references(PlannerInfo *root, Join *join, int rtoffset)
 										(Index) 0,
 										rtoffset,
 										NRM_EQUAL,
-										NUM_EXEC_QUAL((Plan *) join));
+										NUM_EXEC_QUAL((Plan *) join),
+										&join->outer_reference_attrs,
+										&join->inner_reference_attrs);
 
 		/*
 		 * HashJoin's hashkeys are used to look for matching tuples from its
@@ -2368,7 +2608,9 @@ set_join_references(PlannerInfo *root, Join *join, int rtoffset)
 										  (Index) 0,
 										  rtoffset,
 										  (join->jointype == JOIN_INNER ? NRM_EQUAL : NRM_SUPERSET),
-										  NUM_EXEC_TLIST((Plan *) join));
+										  NUM_EXEC_TLIST((Plan *) join),
+										  &join->outer_reference_attrs,
+										  &join->inner_reference_attrs);
 	join->plan.qual = fix_join_expr(root,
 									join->plan.qual,
 									outer_itlist,
@@ -2376,8 +2618,20 @@ set_join_references(PlannerInfo *root, Join *join, int rtoffset)
 									(Index) 0,
 									rtoffset,
 									(join->jointype == JOIN_INNER ? NRM_EQUAL : NRM_SUPERSET),
-									NUM_EXEC_QUAL((Plan *) join));
-
+									NUM_EXEC_QUAL((Plan *) join),
+									&join->outer_reference_attrs,
+									&join->inner_reference_attrs);
+
+	join->plan.forbid_pre_detoast_vars = fix_join_expr(root,
+													   join->plan.forbid_pre_detoast_vars,
+													   outer_itlist,
+													   inner_itlist,
+													   (Index) 0,
+													   rtoffset,
+													   (join->jointype == JOIN_INNER ? NRM_EQUAL : NRM_SUPERSET),
+													   NUM_EXEC_TLIST((Plan *) join),
+													   NULL,
+													   NULL);
 	pfree(outer_itlist);
 	pfree(inner_itlist);
 }
@@ -3010,9 +3264,12 @@ fix_join_expr(PlannerInfo *root,
 			  Index acceptable_rel,
 			  int rtoffset,
 			  NullingRelsMatch nrm_match,
-			  double num_exec)
+			  double num_exec,
+			  Bitmapset **outer_reference_attrs,
+			  Bitmapset **inner_reference_attrs)
 {
 	fix_join_expr_context context;
+	List	   *ret;
 
 	context.root = root;
 	context.outer_itlist = outer_itlist;
@@ -3021,16 +3278,30 @@ fix_join_expr(PlannerInfo *root,
 	context.rtoffset = rtoffset;
 	context.nrm_match = nrm_match;
 	context.num_exec = num_exec;
-	return (List *) fix_join_expr_mutator((Node *) clauses, &context);
+
+	setup_intermediate_level_ctx(&context.level_ctx);
+	setup_intermediate_var_ref_ctx(&context.outer_reference_attrs, outer_reference_attrs);
+	setup_intermediate_var_ref_ctx(&context.inner_reference_attrs, inner_reference_attrs);
+
+	ret = (List *) fix_join_expr_mutator((Node *) clauses, &context);
+
+	bms_free(context.outer_reference_attrs.existing_attrs);
+	bms_free(context.inner_reference_attrs.existing_attrs);
+
+	return ret;
 }
 
 static Node *
 fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 {
 	Var		   *newvar;
+	Node	   *ret_node;
 
 	if (node == NULL)
 		return NULL;
+
+	increase_level_for_pre_detoast(node, &context->level_ctx);
+
 	if (IsA(node, Var))
 	{
 		Var		   *var = (Var *) node;
@@ -3044,7 +3315,13 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 												  context->rtoffset,
 												  context->nrm_match);
 			if (newvar)
+			{
+				add_pre_detoast_vars(&context->level_ctx,
+									 &context->outer_reference_attrs,
+									 newvar);
+				decreased_level_for_pre_detoast(&context->level_ctx);
 				return (Node *) newvar;
+			}
 		}
 
 		/* then in the inner. */
@@ -3056,7 +3333,13 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 												  context->rtoffset,
 												  context->nrm_match);
 			if (newvar)
+			{
+				add_pre_detoast_vars(&context->level_ctx,
+									 &context->inner_reference_attrs,
+									 newvar);
+				decreased_level_for_pre_detoast(&context->level_ctx);
 				return (Node *) newvar;
+			}
 		}
 
 		/* If it's for acceptable_rel, adjust and return it */
@@ -3066,6 +3349,9 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 			var->varno += context->rtoffset;
 			if (var->varnosyn > 0)
 				var->varnosyn += context->rtoffset;
+			/* XXX acceptable_rel?  we can ignore it for safety. */
+			decreased_level_for_pre_detoast(&context->level_ctx);
+
 			return (Node *) var;
 		}
 
@@ -3084,22 +3370,38 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 												  OUTER_VAR,
 												  context->nrm_match);
 			if (newvar)
+			{
+				add_pre_detoast_vars(&context->level_ctx,
+									 &context->outer_reference_attrs,
+									 newvar);
+				decreased_level_for_pre_detoast(&context->level_ctx);
 				return (Node *) newvar;
+			}
 		}
 		if (context->inner_itlist && context->inner_itlist->has_ph_vars)
 		{
+
 			newvar = search_indexed_tlist_for_phv(phv,
 												  context->inner_itlist,
 												  INNER_VAR,
 												  context->nrm_match);
 			if (newvar)
+			{
+				add_pre_detoast_vars(&context->level_ctx,
+									 &context->inner_reference_attrs,
+									 newvar);
+				decreased_level_for_pre_detoast(&context->level_ctx);
 				return (Node *) newvar;
+			}
 		}
 
 		/* If not supplied by input plans, evaluate the contained expr */
 		/* XXX can we assert something about phnullingrels? */
-		return fix_join_expr_mutator((Node *) phv->phexpr, context);
+		ret_node = fix_join_expr_mutator((Node *) phv->phexpr, context);
+		decreased_level_for_pre_detoast(&context->level_ctx);
+		return ret_node;
 	}
+
 	/* Try matching more complex expressions too, if tlists have any */
 	if (context->outer_itlist && context->outer_itlist->has_non_vars)
 	{
@@ -3107,7 +3409,13 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 												  context->outer_itlist,
 												  OUTER_VAR);
 		if (newvar)
+		{
+			add_pre_detoast_vars(&context->level_ctx,
+								 &context->outer_reference_attrs,
+								 newvar);
+			decreased_level_for_pre_detoast(&context->level_ctx);
 			return (Node *) newvar;
+		}
 	}
 	if (context->inner_itlist && context->inner_itlist->has_non_vars)
 	{
@@ -3115,20 +3423,36 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 												  context->inner_itlist,
 												  INNER_VAR);
 		if (newvar)
+		{
+			add_pre_detoast_vars(&context->level_ctx,
+								 &context->inner_reference_attrs,
+								 newvar);
+			decreased_level_for_pre_detoast(&context->level_ctx);
 			return (Node *) newvar;
+		}
 	}
 	/* Special cases (apply only AFTER failing to match to lower tlist) */
 	if (IsA(node, Param))
-		return fix_param_node(context->root, (Param *) node);
+	{
+		ret_node = fix_param_node(context->root, (Param *) node);
+		decreased_level_for_pre_detoast(&context->level_ctx);
+		return ret_node;
+	}
 	if (IsA(node, AlternativeSubPlan))
-		return fix_join_expr_mutator(fix_alternative_subplan(context->root,
-															 (AlternativeSubPlan *) node,
-															 context->num_exec),
-									 context);
+	{
+		ret_node = fix_join_expr_mutator(fix_alternative_subplan(context->root,
+																 (AlternativeSubPlan *) node,
+																 context->num_exec),
+										 context);
+		decreased_level_for_pre_detoast(&context->level_ctx);
+		return ret_node;
+	}
 	fix_expr_common(context->root, node);
-	return expression_tree_mutator(node,
-								   fix_join_expr_mutator,
-								   (void *) context);
+	ret_node = expression_tree_mutator(node,
+									   fix_join_expr_mutator,
+									   (void *) context);
+	decreased_level_for_pre_detoast(&context->level_ctx);
+	return ret_node;
 }
 
 /*
@@ -3163,7 +3487,8 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
  * varno = newvarno, varattno = resno of corresponding targetlist element.
  * The original tree is not modified.
  */
-static Node *
+static Node *					/* XXX: shall I care about this for shared
+								 * detoast optimization? */
 fix_upper_expr(PlannerInfo *root,
 			   Node *node,
 			   indexed_tlist *subplan_itlist,
@@ -3318,7 +3643,10 @@ set_returning_clause_references(PlannerInfo *root,
 						  resultRelation,
 						  rtoffset,
 						  NRM_EQUAL,
-						  NUM_EXEC_TLIST(topplan));
+						  NUM_EXEC_TLIST(topplan),
+						  NULL,
+						  NULL
+		);
 
 	pfree(itlist);
 
diff --git a/src/include/executor/execExpr.h b/src/include/executor/execExpr.h
index a20c539a25..9a31e083dd 100644
--- a/src/include/executor/execExpr.h
+++ b/src/include/executor/execExpr.h
@@ -77,6 +77,11 @@ typedef enum ExprEvalOp
 	EEOP_OUTER_VAR,
 	EEOP_SCAN_VAR,
 
+	/* compute non-system Var value with shared-detoast-datum logic */
+	EEOP_INNER_VAR_TOAST,
+	EEOP_OUTER_VAR_TOAST,
+	EEOP_SCAN_VAR_TOAST,
+
 	/* compute system Var value */
 	EEOP_INNER_SYSVAR,
 	EEOP_OUTER_SYSVAR,
@@ -826,5 +831,6 @@ extern void ExecEvalAggOrderedTransDatum(ExprState *state, ExprEvalStep *op,
 										 ExprContext *econtext);
 extern void ExecEvalAggOrderedTransTuple(ExprState *state, ExprEvalStep *op,
 										 ExprContext *econtext);
+extern void ExecSlotDetoastDatumExternal(TupleTableSlot *slot, int attnum);
 
 #endif							/* EXEC_EXPR_H */
diff --git a/src/include/executor/tuptable.h b/src/include/executor/tuptable.h
index 6133dbcd0a..f660ebec28 100644
--- a/src/include/executor/tuptable.h
+++ b/src/include/executor/tuptable.h
@@ -18,6 +18,7 @@
 #include "access/htup_details.h"
 #include "access/sysattr.h"
 #include "access/tupdesc.h"
+#include "nodes/bitmapset.h"
 #include "storage/buf.h"
 
 /*----------
@@ -128,6 +129,11 @@ typedef struct TupleTableSlot
 	MemoryContext tts_mcxt;		/* slot itself is in this context */
 	ItemPointerData tts_tid;	/* stored tuple's tid */
 	Oid			tts_tableOid;	/* table oid of tuple */
+
+	/*
+	 * The attributes populated by EEOP_{INNER/OUTER/SCAN}_VAR_TOAST step.
+	 */
+	Bitset	   *pre_detoasted_attrs;
 } TupleTableSlot;
 
 /* routines for a TupleTableSlot implementation */
@@ -426,12 +432,38 @@ slot_getsysattr(TupleTableSlot *slot, int attnum, bool *isnull)
 	return slot->tts_ops->getsysattr(slot, attnum, isnull);
 }
 
+static inline void
+ExecFreePreDetoastDatum(TupleTableSlot *slot)
+{
+	int			attnum;
+
+	if (bitset_is_empty(slot->pre_detoasted_attrs))
+		return;
+
+	attnum = -1;
+	/* free the memory used by pre-detoasted datum and reset the flags. */
+	while ((attnum = bitset_next_member(slot->pre_detoasted_attrs, attnum)) >= 0)
+	{
+		pfree((void *) slot->tts_values[attnum]);
+	}
+
+	/*
+	 * bms_free each time cost too much, so just zero these bits and keep its
+	 * memory, just like what we did for TupleTableSlot. but.. see the
+	 * comments about the bms_zero.
+	 */
+	bitset_clear(slot->pre_detoasted_attrs);
+}
+
+
 /*
  * ExecClearTuple - clear the slot's contents
  */
 static inline TupleTableSlot *
 ExecClearTuple(TupleTableSlot *slot)
 {
+	ExecFreePreDetoastDatum(slot);
+
 	slot->tts_ops->clear(slot);
 
 	return slot;
@@ -450,6 +482,10 @@ ExecClearTuple(TupleTableSlot *slot)
 static inline void
 ExecMaterializeSlot(TupleTableSlot *slot)
 {
+	/*
+	 * XXX: pre_detoasted_attrs doesn't dependent on any external storage, so
+	 * nothing should be done here.
+	 */
 	slot->tts_ops->materialize(slot);
 }
 
@@ -494,6 +530,30 @@ ExecCopySlot(TupleTableSlot *dstslot, TupleTableSlot *srcslot)
 
 	dstslot->tts_ops->copyslot(dstslot, srcslot);
 
+	/* Assert this assumption the below code depends on. */
+	Assert(dstslot->tts_nvalid == 0 ||
+		   dstslot->tts_nvalid == srcslot->tts_nvalid);
+
+	if (dstslot->tts_nvalid == srcslot->tts_nvalid &&
+		!bitset_is_empty(srcslot->pre_detoasted_attrs))
+	{
+		int			attnum = -1;
+		MemoryContext old = MemoryContextSwitchTo(dstslot->tts_mcxt);
+
+		dstslot->pre_detoasted_attrs = bitset_copy(srcslot->pre_detoasted_attrs);
+
+		while ((attnum = bitset_next_member(dstslot->pre_detoasted_attrs, attnum)) >= 0)
+		{
+			struct varlena *datum = (struct varlena *) srcslot->tts_values[attnum];
+			Size		len;
+
+			Assert(!VARATT_IS_EXTENDED(datum));
+			len = VARSIZE(datum);
+			dstslot->tts_values[attnum] = (Datum) palloc(len);
+			memcpy((void *) dstslot->tts_values[attnum], datum, len);
+		}
+		MemoryContextSwitchTo(old);
+	}
 	return dstslot;
 }
 
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 561fdd98f1..72febbd37d 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1474,6 +1474,7 @@ typedef struct ScanState
 	Relation	ss_currentRelation;
 	struct TableScanDescData *ss_currentScanDesc;
 	TupleTableSlot *ss_ScanTupleSlot;
+	Bitmapset  *scan_pre_detoast_attrs;
 } ScanState;
 
 /* ----------------
@@ -2003,6 +2004,8 @@ typedef struct JoinState
 	bool		single_match;	/* True if we should skip to next outer tuple
 								 * after finding one inner match */
 	ExprState  *joinqual;		/* JOIN quals (in addition to ps.qual) */
+	Bitmapset  *outer_pre_detoast_attrs;
+	Bitmapset  *inner_pre_detoast_attrs;
 } JoinState;
 
 /* ----------------
@@ -2764,4 +2767,5 @@ typedef struct LimitState
 	TupleTableSlot *last_slot;	/* slot for evaluation of ties */
 } LimitState;
 
+extern void SetPredetoastAttrsForJoin(JoinState *joinstate);
 #endif							/* EXECNODES_H */
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index b4ef6bc44c..79c442385a 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -169,6 +169,13 @@ typedef struct Plan
 	 */
 	Bitmapset  *extParam;
 	Bitmapset  *allParam;
+
+	/*
+	 * A list of Vars which should not apply the shared-detoast-datum logic
+	 * since the upper nodes like Sort/Hash wants them as small as possible.
+	 * Its a subset of targetlist in each Plan node.
+	 */
+	List	   *forbid_pre_detoast_vars;
 } Plan;
 
 /* ----------------
@@ -385,6 +392,13 @@ typedef struct Scan
 
 	Plan		plan;
 	Index		scanrelid;		/* relid is index into the range table */
+
+	/*
+	 * Records of var's varattno - 1 where the Var is accessed indirectly by
+	 * any expression, like a > 3.  However a IS [NOT] NULL is not included
+	 * since it doesn't access the tts_values[*] at all.
+	 */
+	Bitmapset  *reference_attrs;
 } Scan;
 
 /* ----------------
@@ -789,6 +803,14 @@ typedef struct Join
 	JoinType	jointype;
 	bool		inner_unique;
 	List	   *joinqual;		/* JOIN quals (in addition to plan.qual) */
+
+	/*
+	 * Records of var's varattno - 1 where the Var is accessed indirectly by
+	 * any expression, like a > 3.  However a IS [NOT] NULL is not included
+	 * since it doesn't access the tts_values[*] at all.
+	 */
+	Bitmapset  *outer_reference_attrs;
+	Bitmapset  *inner_reference_attrs;
 } Join;
 
 /* ----------------
@@ -869,6 +891,11 @@ typedef struct HashJoin
 	 * perform lookups in the hashtable over the inner plan.
 	 */
 	List	   *hashkeys;
+
+	/*
+	 * Whether the left plan tree should use a SMALL_TLIST.
+	 */
+	bool		left_small_tlist;
 } HashJoin;
 
 /* ----------------
@@ -1588,4 +1615,24 @@ typedef enum MonotonicFunction
 	MONOTONICFUNC_BOTH = MONOTONICFUNC_INCREASING | MONOTONICFUNC_DECREASING,
 } MonotonicFunction;
 
+static inline bool
+is_join_plan(Plan *plan)
+{
+	return (plan != NULL) && (IsA(plan, NestLoop) || IsA(plan, HashJoin) || IsA(plan, MergeJoin));
+}
+
+static inline bool
+is_scan_plan(Plan *plan)
+{
+	return (plan != NULL) &&
+		(IsA(plan, SeqScan) ||
+		 IsA(plan, SampleScan) ||
+		 IsA(plan, IndexScan) ||
+		 IsA(plan, IndexOnlyScan) ||
+		 IsA(plan, BitmapIndexScan) ||
+		 IsA(plan, BitmapHeapScan) ||
+		 IsA(plan, TidScan) ||
+		 IsA(plan, SubqueryScan));
+}
+
 #endif							/* PLANNODES_H */
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 50b06fd878..078d6e0728 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -4043,6 +4043,8 @@ cb_cleanup_dir
 cb_options
 cb_tablespace
 cb_tablespace_mapping
+intermediate_var_ref_context
+intermediate_level_context
 manifest_data
 manifest_writer
 rfile
-- 
2.34.1

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