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diff --git a/src/backend/executor/execJunk.c b/src/backend/executor/execJunk.c
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+/*-------------------------------------------------------------------------
+ *
+ * execJunk.c
+ *	  Junk attribute support stuff....
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/executor/execJunk.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "executor/executor.h"
+
+/*-------------------------------------------------------------------------
+ *		XXX this stuff should be rewritten to take advantage
+ *			of ExecProject() and the ProjectionInfo node.
+ *			-cim 6/3/91
+ *
+ * An attribute of a tuple living inside the executor, can be
+ * either a normal attribute or a "junk" attribute. "junk" attributes
+ * never make it out of the executor, i.e. they are never printed,
+ * returned or stored on disk. Their only purpose in life is to
+ * store some information useful only to the executor, mainly the values
+ * of system attributes like "ctid", or sort key columns that are not to
+ * be output.
+ *
+ * The general idea is the following: A target list consists of a list of
+ * TargetEntry nodes containing expressions. Each TargetEntry has a field
+ * called 'resjunk'. If the value of this field is true then the
+ * corresponding attribute is a "junk" attribute.
+ *
+ * When we initialize a plan we call ExecInitJunkFilter to create a filter.
+ *
+ * We then execute the plan, treating the resjunk attributes like any others.
+ *
+ * Finally, when at the top level we get back a tuple, we can call
+ * ExecFindJunkAttribute/ExecGetJunkAttribute to retrieve the values of the
+ * junk attributes we are interested in, and ExecFilterJunk to remove all the
+ * junk attributes from a tuple.  This new "clean" tuple is then printed,
+ * inserted, or updated.
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/*
+ * ExecInitJunkFilter
+ *
+ * Initialize the Junk filter.
+ *
+ * The source targetlist is passed in.  The output tuple descriptor is
+ * built from the non-junk tlist entries.
+ * An optional resultSlot can be passed as well; otherwise, we create one.
+ */
+JunkFilter *
+ExecInitJunkFilter(List *targetList, TupleTableSlot *slot)
+{
+	JunkFilter *junkfilter;
+	TupleDesc	cleanTupType;
+	int			cleanLength;
+	AttrNumber *cleanMap;
+
+	/*
+	 * Compute the tuple descriptor for the cleaned tuple.
+	 */
+	cleanTupType = ExecCleanTypeFromTL(targetList);
+
+	/*
+	 * Use the given slot, or make a new slot if we weren't given one.
+	 */
+	if (slot)
+		ExecSetSlotDescriptor(slot, cleanTupType);
+	else
+		slot = MakeSingleTupleTableSlot(cleanTupType, &TTSOpsVirtual);
+
+	/*
+	 * Now calculate the mapping between the original tuple's attributes and
+	 * the "clean" tuple's attributes.
+	 *
+	 * The "map" is an array of "cleanLength" attribute numbers, i.e. one
+	 * entry for every attribute of the "clean" tuple. The value of this entry
+	 * is the attribute number of the corresponding attribute of the
+	 * "original" tuple.  (Zero indicates a NULL output attribute, but we do
+	 * not use that feature in this routine.)
+	 */
+	cleanLength = cleanTupType->natts;
+	if (cleanLength > 0)
+	{
+		AttrNumber	cleanResno;
+		ListCell   *t;
+
+		cleanMap = (AttrNumber *) palloc(cleanLength * sizeof(AttrNumber));
+		cleanResno = 0;
+		foreach(t, targetList)
+		{
+			TargetEntry *tle = lfirst(t);
+
+			if (!tle->resjunk)
+			{
+				cleanMap[cleanResno] = tle->resno;
+				cleanResno++;
+			}
+		}
+		Assert(cleanResno == cleanLength);
+	}
+	else
+		cleanMap = NULL;
+
+	/*
+	 * Finally create and initialize the JunkFilter struct.
+	 */
+	junkfilter = makeNode(JunkFilter);
+
+	junkfilter->jf_targetList = targetList;
+	junkfilter->jf_cleanTupType = cleanTupType;
+	junkfilter->jf_cleanMap = cleanMap;
+	junkfilter->jf_resultSlot = slot;
+
+	return junkfilter;
+}
+
+/*
+ * ExecInitJunkFilterConversion
+ *
+ * Initialize a JunkFilter for rowtype conversions.
+ *
+ * Here, we are given the target "clean" tuple descriptor rather than
+ * inferring it from the targetlist.  The target descriptor can contain
+ * deleted columns.  It is assumed that the caller has checked that the
+ * non-deleted columns match up with the non-junk columns of the targetlist.
+ */
+JunkFilter *
+ExecInitJunkFilterConversion(List *targetList,
+							 TupleDesc cleanTupType,
+							 TupleTableSlot *slot)
+{
+	JunkFilter *junkfilter;
+	int			cleanLength;
+	AttrNumber *cleanMap;
+	ListCell   *t;
+	int			i;
+
+	/*
+	 * Use the given slot, or make a new slot if we weren't given one.
+	 */
+	if (slot)
+		ExecSetSlotDescriptor(slot, cleanTupType);
+	else
+		slot = MakeSingleTupleTableSlot(cleanTupType, &TTSOpsVirtual);
+
+	/*
+	 * Calculate the mapping between the original tuple's attributes and the
+	 * "clean" tuple's attributes.
+	 *
+	 * The "map" is an array of "cleanLength" attribute numbers, i.e. one
+	 * entry for every attribute of the "clean" tuple. The value of this entry
+	 * is the attribute number of the corresponding attribute of the
+	 * "original" tuple.  We store zero for any deleted attributes, marking
+	 * that a NULL is needed in the output tuple.
+	 */
+	cleanLength = cleanTupType->natts;
+	if (cleanLength > 0)
+	{
+		cleanMap = (AttrNumber *) palloc0(cleanLength * sizeof(AttrNumber));
+		t = list_head(targetList);
+		for (i = 0; i < cleanLength; i++)
+		{
+			if (TupleDescAttr(cleanTupType, i)->attisdropped)
+				continue;		/* map entry is already zero */
+			for (;;)
+			{
+				TargetEntry *tle = lfirst(t);
+
+				t = lnext(targetList, t);
+				if (!tle->resjunk)
+				{
+					cleanMap[i] = tle->resno;
+					break;
+				}
+			}
+		}
+	}
+	else
+		cleanMap = NULL;
+
+	/*
+	 * Finally create and initialize the JunkFilter struct.
+	 */
+	junkfilter = makeNode(JunkFilter);
+
+	junkfilter->jf_targetList = targetList;
+	junkfilter->jf_cleanTupType = cleanTupType;
+	junkfilter->jf_cleanMap = cleanMap;
+	junkfilter->jf_resultSlot = slot;
+
+	return junkfilter;
+}
+
+/*
+ * ExecFindJunkAttribute
+ *
+ * Locate the specified junk attribute in the junk filter's targetlist,
+ * and return its resno.  Returns InvalidAttrNumber if not found.
+ */
+AttrNumber
+ExecFindJunkAttribute(JunkFilter *junkfilter, const char *attrName)
+{
+	return ExecFindJunkAttributeInTlist(junkfilter->jf_targetList, attrName);
+}
+
+/*
+ * ExecFindJunkAttributeInTlist
+ *
+ * Find a junk attribute given a subplan's targetlist (not necessarily
+ * part of a JunkFilter).
+ */
+AttrNumber
+ExecFindJunkAttributeInTlist(List *targetlist, const char *attrName)
+{
+	ListCell   *t;
+
+	foreach(t, targetlist)
+	{
+		TargetEntry *tle = lfirst(t);
+
+		if (tle->resjunk && tle->resname &&
+			(strcmp(tle->resname, attrName) == 0))
+		{
+			/* We found it ! */
+			return tle->resno;
+		}
+	}
+
+	return InvalidAttrNumber;
+}
+
+/*
+ * ExecFilterJunk
+ *
+ * Construct and return a slot with all the junk attributes removed.
+ */
+TupleTableSlot *
+ExecFilterJunk(JunkFilter *junkfilter, TupleTableSlot *slot)
+{
+	TupleTableSlot *resultSlot;
+	AttrNumber *cleanMap;
+	TupleDesc	cleanTupType;
+	int			cleanLength;
+	int			i;
+	Datum	   *values;
+	bool	   *isnull;
+	Datum	   *old_values;
+	bool	   *old_isnull;
+
+	/*
+	 * Extract all the values of the old tuple.
+	 */
+	slot_getallattrs(slot);
+	old_values = slot->tts_values;
+	old_isnull = slot->tts_isnull;
+
+	/*
+	 * get info from the junk filter
+	 */
+	cleanTupType = junkfilter->jf_cleanTupType;
+	cleanLength = cleanTupType->natts;
+	cleanMap = junkfilter->jf_cleanMap;
+	resultSlot = junkfilter->jf_resultSlot;
+
+	/*
+	 * Prepare to build a virtual result tuple.
+	 */
+	ExecClearTuple(resultSlot);
+	values = resultSlot->tts_values;
+	isnull = resultSlot->tts_isnull;
+
+	/*
+	 * Transpose data into proper fields of the new tuple.
+	 */
+	for (i = 0; i < cleanLength; i++)
+	{
+		int			j = cleanMap[i];
+
+		if (j == 0)
+		{
+			values[i] = (Datum) 0;
+			isnull[i] = true;
+		}
+		else
+		{
+			values[i] = old_values[j - 1];
+			isnull[i] = old_isnull[j - 1];
+		}
+	}
+
+	/*
+	 * And return the virtual tuple.
+	 */
+	return ExecStoreVirtualTuple(resultSlot);
+}