v1-0001-Rework-attribute-mappings.patch

From 48f8b82974fd36d807b524abbb7b8d605a50ca94 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Thu, 21 Nov 2019 13:23:16 +0900
Subject: [PATCH v1] Rework attribute mappings

---
 src/backend/access/common/Makefile         |  1 +
 src/backend/access/common/attmap.c         | 51 ++++++++++++++++
 src/backend/access/common/tupconvert.c     | 61 ++++++++++---------
 src/backend/catalog/index.c                | 10 ++--
 src/backend/catalog/partition.c            |  7 +--
 src/backend/commands/indexcmds.c           | 12 ++--
 src/backend/commands/tablecmds.c           | 69 +++++++++++-----------
 src/backend/executor/execMain.c            |  8 +--
 src/backend/executor/execPartition.c       | 41 ++++++-------
 src/backend/parser/parse_utilcmd.c         | 18 +++---
 src/backend/replication/logical/relation.c | 10 ++--
 src/backend/replication/logical/worker.c   |  9 ++-
 src/backend/rewrite/rewriteManip.c         | 12 ++--
 src/include/access/attmap.h                | 42 +++++++++++++
 src/include/access/tupconvert.h            | 16 ++---
 src/include/catalog/index.h                |  2 +-
 src/include/parser/parse_utilcmd.h         |  3 +-
 src/include/replication/logicalrelation.h  |  2 +-
 src/include/rewrite/rewriteManip.h         |  3 +-
 19 files changed, 236 insertions(+), 141 deletions(-)
 create mode 100644 src/backend/access/common/attmap.c
 create mode 100644 src/include/access/attmap.h

diff --git a/src/backend/access/common/Makefile b/src/backend/access/common/Makefile
index 6c9c6f3256..fd74e14024 100644
--- a/src/backend/access/common/Makefile
+++ b/src/backend/access/common/Makefile
@@ -13,6 +13,7 @@ top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
 OBJS = \
+	attmap.o \
 	bufmask.o \
 	detoast.o \
 	heaptuple.o \
diff --git a/src/backend/access/common/attmap.c b/src/backend/access/common/attmap.c
new file mode 100644
index 0000000000..06df1dcfa4
--- /dev/null
+++ b/src/backend/access/common/attmap.c
@@ -0,0 +1,51 @@
+/*-------------------------------------------------------------------------
+ *
+ * attmap.c
+ *	  Attribute mapping support.
+ *
+ * This file provides utility routines to build and managed attribute
+ * mappings which are used when working on inheritance and partition trees
+ * for cloned object creation or tuple attribute comparison for runtime
+ * operations.
+ *
+ * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/attmap.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/attmap.h"
+
+/*
+ * make_attrmap
+ *
+ * Utility routine to allocate an attribute map in the current memory
+ * context.
+ */
+AttrMap *
+make_attrmap(int maplen)
+{
+	AttrMap	   *res;
+
+	res = (AttrMap *) palloc0(sizeof(AttrMap));
+	res->maplen = maplen;
+	res->attnums = (AttrNumber *) palloc0(sizeof(AttrNumber) * maplen);
+	return res;
+}
+
+/*
+ * free_attrmap
+ *
+ * Utility routine to release an attribute map.
+ */
+void
+free_attrmap(AttrMap *map)
+{
+	pfree(map->attnums);
+	pfree(map);
+}
diff --git a/src/backend/access/common/tupconvert.c b/src/backend/access/common/tupconvert.c
index 0ec9cd5870..94b90d6115 100644
--- a/src/backend/access/common/tupconvert.c
+++ b/src/backend/access/common/tupconvert.c
@@ -67,7 +67,7 @@ convert_tuples_by_position(TupleDesc indesc,
 						   const char *msg)
 {
 	TupleConversionMap *map;
-	AttrNumber *attrMap;
+	AttrMap    *attrMap;
 	int			nincols;
 	int			noutcols;
 	int			n;
@@ -77,7 +77,13 @@ convert_tuples_by_position(TupleDesc indesc,
 
 	/* Verify compatibility and prepare attribute-number map */
 	n = outdesc->natts;
-	attrMap = (AttrNumber *) palloc0(n * sizeof(AttrNumber));
+
+	/*
+	 * The length is computed as the number of attributes of the expected
+	 * rowtype as it includes dropped attributes in its count.
+	 */
+	attrMap = make_attrmap(n);
+
 	j = 0;						/* j is next physical input attribute */
 	nincols = noutcols = 0;		/* these count non-dropped attributes */
 	same = true;
@@ -88,7 +94,7 @@ convert_tuples_by_position(TupleDesc indesc,
 		int32		atttypmod;
 
 		if (att->attisdropped)
-			continue;			/* attrMap[i] is already 0 */
+			continue;			/* attrMap->attnums[i] is already 0 */
 		noutcols++;
 		atttypid = att->atttypid;
 		atttypmod = att->atttypmod;
@@ -110,11 +116,11 @@ convert_tuples_by_position(TupleDesc indesc,
 								   format_type_with_typemod(atttypid,
 															atttypmod),
 								   noutcols)));
-			attrMap[i] = (AttrNumber) (j + 1);
+			attrMap->attnums[i] = (AttrNumber) (j + 1);
 			j++;
 			break;
 		}
-		if (attrMap[i] == 0)
+		if (attrMap->attnums[i] == 0)
 			same = false;		/* we'll complain below */
 	}
 
@@ -147,7 +153,7 @@ convert_tuples_by_position(TupleDesc indesc,
 			Form_pg_attribute inatt;
 			Form_pg_attribute outatt;
 
-			if (attrMap[i] == (i + 1))
+			if (attrMap->attnums[i] == (i + 1))
 				continue;
 
 			/*
@@ -157,7 +163,7 @@ convert_tuples_by_position(TupleDesc indesc,
 			 */
 			inatt = TupleDescAttr(indesc, i);
 			outatt = TupleDescAttr(outdesc, i);
-			if (attrMap[i] == 0 &&
+			if (attrMap->attnums[i] == 0 &&
 				inatt->attisdropped &&
 				inatt->attlen == outatt->attlen &&
 				inatt->attalign == outatt->attalign)
@@ -173,7 +179,7 @@ convert_tuples_by_position(TupleDesc indesc,
 	if (same)
 	{
 		/* Runtime conversion is not needed */
-		pfree(attrMap);
+		free_attrmap(attrMap);
 		return NULL;
 	}
 
@@ -206,7 +212,7 @@ convert_tuples_by_name(TupleDesc indesc,
 					   TupleDesc outdesc)
 {
 	TupleConversionMap *map;
-	AttrNumber *attrMap;
+	AttrMap *attrMap;
 	int			n = outdesc->natts;
 
 	/* Verify compatibility and prepare attribute-number map */
@@ -241,11 +247,11 @@ convert_tuples_by_name(TupleDesc indesc,
  * output.)  This is normally a subroutine for convert_tuples_by_name, but can
  * be used standalone.
  */
-AttrNumber *
+AttrMap *
 convert_tuples_by_name_map(TupleDesc indesc,
 						   TupleDesc outdesc)
 {
-	AttrNumber *attrMap;
+	AttrMap	   *attrMap;
 	int			outnatts;
 	int			innatts;
 	int			i;
@@ -254,7 +260,7 @@ convert_tuples_by_name_map(TupleDesc indesc,
 	outnatts = outdesc->natts;
 	innatts = indesc->natts;
 
-	attrMap = (AttrNumber *) palloc0(outnatts * sizeof(AttrNumber));
+	attrMap = make_attrmap(outnatts);
 	for (i = 0; i < outnatts; i++)
 	{
 		Form_pg_attribute outatt = TupleDescAttr(outdesc, i);
@@ -264,7 +270,7 @@ convert_tuples_by_name_map(TupleDesc indesc,
 		int			j;
 
 		if (outatt->attisdropped)
-			continue;			/* attrMap[i] is already 0 */
+			continue;			/* attrMap->attnums[i] is already 0 */
 		attname = NameStr(outatt->attname);
 		atttypid = outatt->atttypid;
 		atttypmod = outatt->atttypmod;
@@ -302,11 +308,11 @@ convert_tuples_by_name_map(TupleDesc indesc,
 									   attname,
 									   format_type_be(outdesc->tdtypeid),
 									   format_type_be(indesc->tdtypeid))));
-				attrMap[i] = inatt->attnum;
+				attrMap->attnums[i] = inatt->attnum;
 				break;
 			}
 		}
-		if (attrMap[i] == 0)
+		if (attrMap->attnums[i] == 0)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATATYPE_MISMATCH),
 					 errmsg("could not convert row type"),
@@ -323,11 +329,11 @@ convert_tuples_by_name_map(TupleDesc indesc,
  * conversion not required. This is a convenience routine for
  * convert_tuples_by_name() and other functions.
  */
-AttrNumber *
+AttrMap *
 convert_tuples_by_name_map_if_req(TupleDesc indesc,
 								  TupleDesc outdesc)
 {
-	AttrNumber *attrMap;
+	AttrMap	   *attrMap;
 	int			n = outdesc->natts;
 	int			i;
 	bool		same;
@@ -347,7 +353,7 @@ convert_tuples_by_name_map_if_req(TupleDesc indesc,
 			Form_pg_attribute inatt;
 			Form_pg_attribute outatt;
 
-			if (attrMap[i] == (i + 1))
+			if (attrMap->attnums[i] == (i + 1))
 				continue;
 
 			/*
@@ -357,7 +363,7 @@ convert_tuples_by_name_map_if_req(TupleDesc indesc,
 			 */
 			inatt = TupleDescAttr(indesc, i);
 			outatt = TupleDescAttr(outdesc, i);
-			if (attrMap[i] == 0 &&
+			if (attrMap->attnums[i] == 0 &&
 				inatt->attisdropped &&
 				inatt->attlen == outatt->attlen &&
 				inatt->attalign == outatt->attalign)
@@ -373,7 +379,7 @@ convert_tuples_by_name_map_if_req(TupleDesc indesc,
 	if (same)
 	{
 		/* Runtime conversion is not needed */
-		pfree(attrMap);
+		free_attrmap(attrMap);
 		return NULL;
 	}
 	else
@@ -386,7 +392,7 @@ convert_tuples_by_name_map_if_req(TupleDesc indesc,
 HeapTuple
 execute_attr_map_tuple(HeapTuple tuple, TupleConversionMap *map)
 {
-	AttrNumber *attrMap = map->attrMap;
+	AttrMap	   *attrMap = map->attrMap;
 	Datum	   *invalues = map->invalues;
 	bool	   *inisnull = map->inisnull;
 	Datum	   *outvalues = map->outvalues;
@@ -404,9 +410,10 @@ execute_attr_map_tuple(HeapTuple tuple, TupleConversionMap *map)
 	/*
 	 * Transpose into proper fields of the new tuple.
 	 */
-	for (i = 0; i < outnatts; i++)
+	Assert(attrMap->maplen == outnatts);
+	for (i = 0; i < attrMap->maplen; i++)
 	{
-		int			j = attrMap[i];
+		int			j = attrMap->attnums[i];
 
 		outvalues[i] = invalues[j];
 		outisnull[i] = inisnull[j];
@@ -422,7 +429,7 @@ execute_attr_map_tuple(HeapTuple tuple, TupleConversionMap *map)
  * Perform conversion of a tuple slot according to the map.
  */
 TupleTableSlot *
-execute_attr_map_slot(AttrNumber *attrMap,
+execute_attr_map_slot(AttrMap *attrMap,
 					  TupleTableSlot *in_slot,
 					  TupleTableSlot *out_slot)
 {
@@ -454,9 +461,9 @@ execute_attr_map_slot(AttrNumber *attrMap,
 	/* Transpose into proper fields of the out slot. */
 	for (i = 0; i < outnatts; i++)
 	{
-		int			j = attrMap[i] - 1;
+		int			j = attrMap->attnums[i] - 1;
 
-		/* attrMap[i] == 0 means it's a NULL datum. */
+		/* attrMap->attnums[i] == 0 means it's a NULL datum. */
 		if (j == -1)
 		{
 			outvalues[i] = (Datum) 0;
@@ -481,7 +488,7 @@ void
 free_conversion_map(TupleConversionMap *map)
 {
 	/* indesc and outdesc are not ours to free */
-	pfree(map->attrMap);
+	free_attrmap(map->attrMap);
 	pfree(map->invalues);
 	pfree(map->inisnull);
 	pfree(map->outvalues);
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 67f637de11..05cab83d7f 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -2338,7 +2338,7 @@ bool
 CompareIndexInfo(IndexInfo *info1, IndexInfo *info2,
 				 Oid *collations1, Oid *collations2,
 				 Oid *opfamilies1, Oid *opfamilies2,
-				 AttrNumber *attmap, int maplen)
+				 AttrMap *attmap)
 {
 	int			i;
 
@@ -2365,12 +2365,12 @@ CompareIndexInfo(IndexInfo *info1, IndexInfo *info2,
 	 */
 	for (i = 0; i < info1->ii_NumIndexAttrs; i++)
 	{
-		if (maplen < info2->ii_IndexAttrNumbers[i])
+		if (attmap->maplen < info2->ii_IndexAttrNumbers[i])
 			elog(ERROR, "incorrect attribute map");
 
 		/* ignore expressions at this stage */
 		if ((info1->ii_IndexAttrNumbers[i] != InvalidAttrNumber) &&
-			(attmap[info2->ii_IndexAttrNumbers[i] - 1] !=
+			(attmap->attnums[info2->ii_IndexAttrNumbers[i] - 1] !=
 			 info1->ii_IndexAttrNumbers[i]))
 			return false;
 
@@ -2396,7 +2396,7 @@ CompareIndexInfo(IndexInfo *info1, IndexInfo *info2,
 		Node	   *mapped;
 
 		mapped = map_variable_attnos((Node *) info2->ii_Expressions,
-									 1, 0, attmap, maplen,
+									 1, 0, attmap,
 									 InvalidOid, &found_whole_row);
 		if (found_whole_row)
 		{
@@ -2420,7 +2420,7 @@ CompareIndexInfo(IndexInfo *info1, IndexInfo *info2,
 		Node	   *mapped;
 
 		mapped = map_variable_attnos((Node *) info2->ii_Predicate,
-									 1, 0, attmap, maplen,
+									 1, 0, attmap,
 									 InvalidOid, &found_whole_row);
 		if (found_whole_row)
 		{
diff --git a/src/backend/catalog/partition.c b/src/backend/catalog/partition.c
index 5dfa4499fd..2b14e9f31a 100644
--- a/src/backend/catalog/partition.c
+++ b/src/backend/catalog/partition.c
@@ -206,14 +206,13 @@ map_partition_varattnos(List *expr, int fromrel_varno,
 
 	if (expr != NIL)
 	{
-		AttrNumber *part_attnos;
+		AttrMap *part_attmap;
 
-		part_attnos = convert_tuples_by_name_map(RelationGetDescr(to_rel),
+		part_attmap = convert_tuples_by_name_map(RelationGetDescr(to_rel),
 												 RelationGetDescr(from_rel));
 		expr = (List *) map_variable_attnos((Node *) expr,
 											fromrel_varno, 0,
-											part_attnos,
-											RelationGetDescr(from_rel)->natts,
+											part_attmap,
 											RelationGetForm(to_rel)->reltype,
 											&my_found_whole_row);
 	}
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 374e2d0efe..d9b61f9875 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1060,9 +1060,8 @@ DefineIndex(Oid relationId,
 				Relation	childrel;
 				List	   *childidxs;
 				ListCell   *cell;
-				AttrNumber *attmap;
+				AttrMap	   *attmap;
 				bool		found = false;
-				int			maplen;
 
 				childrel = table_open(childRelid, lockmode);
 
@@ -1089,7 +1088,6 @@ DefineIndex(Oid relationId,
 				attmap =
 					convert_tuples_by_name_map(RelationGetDescr(childrel),
 											   parentDesc);
-				maplen = parentDesc->natts;
 
 				foreach(cell, childidxs)
 				{
@@ -1108,7 +1106,7 @@ DefineIndex(Oid relationId,
 										 collationObjectId,
 										 cldidx->rd_opfamily,
 										 opfamOids,
-										 attmap, maplen))
+										 attmap))
 					{
 						Oid			cldConstrOid = InvalidOid;
 
@@ -1193,7 +1191,7 @@ DefineIndex(Oid relationId,
 						{
 							ielem->expr =
 								map_variable_attnos((Node *) ielem->expr,
-													1, 0, attmap, maplen,
+													1, 0, attmap,
 													InvalidOid,
 													&found_whole_row);
 							if (found_whole_row)
@@ -1202,7 +1200,7 @@ DefineIndex(Oid relationId,
 					}
 					childStmt->whereClause =
 						map_variable_attnos(stmt->whereClause, 1, 0,
-											attmap, maplen,
+											attmap,
 											InvalidOid, &found_whole_row);
 					if (found_whole_row)
 						elog(ERROR, "cannot convert whole-row table reference");
@@ -1217,7 +1215,7 @@ DefineIndex(Oid relationId,
 
 				pgstat_progress_update_param(PROGRESS_CREATEIDX_PARTITIONS_DONE,
 											 i + 1);
-				pfree(attmap);
+				free_attrmap(attmap);
 			}
 
 			/*
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 45aae5955d..abbb7c0044 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -1072,7 +1072,7 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 		foreach(cell, idxlist)
 		{
 			Relation	idxRel = index_open(lfirst_oid(cell), AccessShareLock);
-			AttrNumber *attmap;
+			AttrMap	   *attmap;
 			IndexStmt  *idxstmt;
 			Oid			constraintOid;
 
@@ -1094,10 +1094,10 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 
 			attmap = convert_tuples_by_name_map(RelationGetDescr(rel),
 												RelationGetDescr(parent));
+
 			idxstmt =
 				generateClonedIndexStmt(NULL, idxRel,
-										attmap, RelationGetDescr(parent)->natts,
-										&constraintOid);
+										attmap, &constraintOid);
 			DefineIndex(RelationGetRelid(rel),
 						idxstmt,
 						InvalidOid,
@@ -2156,7 +2156,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		Relation	relation;
 		TupleDesc	tupleDesc;
 		TupleConstr *constr;
-		AttrNumber *newattno;
+		AttrMap	   *newattmap;
 		AttrNumber	parent_attno;
 
 		/* caller already got lock */
@@ -2237,12 +2237,11 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		constr = tupleDesc->constr;
 
 		/*
-		 * newattno[] will contain the child-table attribute numbers for the
-		 * attributes of this parent table.  (They are not the same for
-		 * parents after the first one, nor if we have dropped columns.)
+		 * newattmap->attnums[] will contain the child-table attribute numbers
+		 * for the attributes of this parent table.  (They are not the same
+		 * for parents after the first one, nor if we have dropped columns.)
 		 */
-		newattno = (AttrNumber *)
-			palloc0(tupleDesc->natts * sizeof(AttrNumber));
+		newattmap = make_attrmap(tupleDesc->natts);
 
 		for (parent_attno = 1; parent_attno <= tupleDesc->natts;
 			 parent_attno++)
@@ -2257,7 +2256,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			 * Ignore dropped columns in the parent.
 			 */
 			if (attribute->attisdropped)
-				continue;		/* leave newattno entry as zero */
+				continue;		/* leave newattmap->attnums entry as zero */
 
 			/*
 			 * Does it conflict with some previously inherited column?
@@ -2315,7 +2314,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				/* Merge of NOT NULL constraints = OR 'em together */
 				def->is_not_null |= attribute->attnotnull;
 				/* Default and other constraints are handled below */
-				newattno[parent_attno - 1] = exist_attno;
+				newattmap->attnums[parent_attno - 1] = exist_attno;
 
 				/* Check for GENERATED conflicts */
 				if (def->generated != attribute->attgenerated)
@@ -2346,7 +2345,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				def->constraints = NIL;
 				def->location = -1;
 				inhSchema = lappend(inhSchema, def);
-				newattno[parent_attno - 1] = ++child_attno;
+				newattmap->attnums[parent_attno - 1] = ++child_attno;
 			}
 
 			/*
@@ -2394,7 +2393,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 
 		/*
 		 * Now copy the CHECK constraints of this parent, adjusting attnos
-		 * using the completed newattno[] map.  Identically named constraints
+		 * using the completed newattmap map.  Identically named constraints
 		 * are merged if possible, else we throw error.
 		 */
 		if (constr && constr->num_check > 0)
@@ -2415,7 +2414,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				/* Adjust Vars to match new table's column numbering */
 				expr = map_variable_attnos(stringToNode(check[i].ccbin),
 										   1, 0,
-										   newattno, tupleDesc->natts,
+										   newattmap,
 										   InvalidOid, &found_whole_row);
 
 				/*
@@ -2452,7 +2451,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			}
 		}
 
-		pfree(newattno);
+		free_attrmap(newattmap);
 
 		/*
 		 * Close the parent rel, but keep our lock on it until xact commit.
@@ -8195,7 +8194,7 @@ addFkRecurseReferenced(List **wqueue, Constraint *fkconstraint, Relation rel,
 		for (int i = 0; i < pd->nparts; i++)
 		{
 			Relation	partRel;
-			AttrNumber *map;
+			AttrMap	   *map;
 			AttrNumber *mapped_pkattnum;
 			Oid			partIndexId;
 
@@ -8211,7 +8210,7 @@ addFkRecurseReferenced(List **wqueue, Constraint *fkconstraint, Relation rel,
 			{
 				mapped_pkattnum = palloc(sizeof(AttrNumber) * numfks);
 				for (int j = 0; j < numfks; j++)
-					mapped_pkattnum[j] = map[pkattnum[j] - 1];
+					mapped_pkattnum[j] = map->attnums[pkattnum[j] - 1];
 			}
 			else
 				mapped_pkattnum = pkattnum;
@@ -8232,7 +8231,7 @@ addFkRecurseReferenced(List **wqueue, Constraint *fkconstraint, Relation rel,
 			if (map)
 			{
 				pfree(mapped_pkattnum);
-				pfree(map);
+				free_attrmap(map);
 			}
 		}
 	}
@@ -8336,7 +8335,7 @@ addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint, Relation rel,
 			Oid			partitionId = pd->oids[i];
 			Relation	partition = table_open(partitionId, lockmode);
 			List	   *partFKs;
-			AttrNumber *attmap;
+			AttrMap	   *attmap;
 			AttrNumber	mapped_fkattnum[INDEX_MAX_KEYS];
 			bool		attached;
 			char	   *conname;
@@ -8349,8 +8348,8 @@ addFkRecurseReferencing(List **wqueue, Constraint *fkconstraint, Relation rel,
 
 			attmap = convert_tuples_by_name_map(RelationGetDescr(partition),
 												RelationGetDescr(rel));
-			for (int j = 0; j < numfks; j++)
-				mapped_fkattnum[j] = attmap[fkattnum[j] - 1];
+			for (int j = 0; j < attmap->maplen; j++)
+				mapped_fkattnum[j] = attmap->attnums[fkattnum[j] - 1];
 
 			/* Check whether an existing constraint can be repurposed */
 			partFKs = copyObject(RelationGetFKeyList(partition));
@@ -8498,7 +8497,7 @@ static void
 CloneFkReferenced(Relation parentRel, Relation partitionRel)
 {
 	Relation	pg_constraint;
-	AttrNumber *attmap;
+	AttrMap	   *attmap;
 	ListCell   *cell;
 	SysScanDesc scan;
 	ScanKeyData key[2];
@@ -8576,8 +8575,9 @@ CloneFkReferenced(Relation parentRel, Relation partitionRel)
 								   conpfeqop,
 								   conppeqop,
 								   conffeqop);
+		Assert(numfks == attmap->maplen);
 		for (int i = 0; i < numfks; i++)
-			mapped_confkey[i] = attmap[confkey[i] - 1];
+			mapped_confkey[i] = attmap->attnums[confkey[i] - 1];
 
 		fkconstraint = makeNode(Constraint);
 		/* for now this is all we need */
@@ -8644,7 +8644,7 @@ CloneFkReferenced(Relation parentRel, Relation partitionRel)
 static void
 CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
 {
-	AttrNumber *attmap;
+	AttrMap	   *attmap;
 	List	   *partFKs;
 	List	   *clone = NIL;
 	ListCell   *cell;
@@ -8723,8 +8723,8 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
 
 		DeconstructFkConstraintRow(tuple, &numfks, conkey, confkey,
 								   conpfeqop, conppeqop, conffeqop);
-		for (int i = 0; i < numfks; i++)
-			mapped_conkey[i] = attmap[conkey[i] - 1];
+		for (int i = 0; i < attmap->maplen; i++)
+			mapped_conkey[i] = attmap->attnums[conkey[i] - 1];
 
 		/*
 		 * Before creating a new constraint, see whether any existing FKs are
@@ -10497,7 +10497,7 @@ ATPrepAlterColumnType(List **wqueue,
 			 */
 			if (def->cooked_default)
 			{
-				AttrNumber *attmap;
+				AttrMap	   *attmap;
 				bool		found_whole_row;
 
 				/* create a copy to scribble on */
@@ -10508,7 +10508,7 @@ ATPrepAlterColumnType(List **wqueue,
 				((ColumnDef *) cmd->def)->cooked_default =
 					map_variable_attnos(def->cooked_default,
 										1, 0,
-										attmap, RelationGetDescr(rel)->natts,
+										attmap,
 										InvalidOid, &found_whole_row);
 				if (found_whole_row)
 					ereport(ERROR,
@@ -15860,7 +15860,7 @@ AttachPartitionEnsureIndexes(Relation rel, Relation attachrel)
 		Oid			idx = lfirst_oid(cell);
 		Relation	idxRel = index_open(idx, AccessShareLock);
 		IndexInfo  *info;
-		AttrNumber *attmap;
+		AttrMap	   *attmap;
 		bool		found = false;
 		Oid			constraintOid;
 
@@ -15899,8 +15899,7 @@ AttachPartitionEnsureIndexes(Relation rel, Relation attachrel)
 								 idxRel->rd_indcollation,
 								 attachrelIdxRels[i]->rd_opfamily,
 								 idxRel->rd_opfamily,
-								 attmap,
-								 RelationGetDescr(rel)->natts))
+								 attmap))
 			{
 				/*
 				 * If this index is being created in the parent because of a
@@ -15941,7 +15940,6 @@ AttachPartitionEnsureIndexes(Relation rel, Relation attachrel)
 
 			stmt = generateClonedIndexStmt(NULL,
 										   idxRel, attmap,
-										   RelationGetDescr(rel)->natts,
 										   &constraintOid);
 			DefineIndex(RelationGetRelid(attachrel), stmt, InvalidOid,
 						RelationGetRelid(idxRel),
@@ -16407,7 +16405,7 @@ ATExecAttachPartitionIdx(List **wqueue, Relation parentIdx, RangeVar *name)
 	{
 		IndexInfo  *childInfo;
 		IndexInfo  *parentInfo;
-		AttrNumber *attmap;
+		AttrMap	   *attmap;
 		bool		found;
 		int			i;
 		PartitionDesc partDesc;
@@ -16459,8 +16457,7 @@ ATExecAttachPartitionIdx(List **wqueue, Relation parentIdx, RangeVar *name)
 							  parentIdx->rd_indcollation,
 							  partIdx->rd_opfamily,
 							  parentIdx->rd_opfamily,
-							  attmap,
-							  RelationGetDescr(parentTbl)->natts))
+							  attmap))
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 					 errmsg("cannot attach index \"%s\" as a partition of index \"%s\"",
@@ -16497,7 +16494,7 @@ ATExecAttachPartitionIdx(List **wqueue, Relation parentIdx, RangeVar *name)
 			ConstraintSetParentConstraint(cldConstrId, constraintOid,
 										  RelationGetRelid(partTbl));
 
-		pfree(attmap);
+		free_attrmap(attmap);
 
 		validatePartitionedIndex(parentIdx, parentTbl);
 	}
diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index c46eb8d646..5f9345c6fe 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -1843,7 +1843,7 @@ ExecPartitionCheckEmitError(ResultRelInfo *resultRelInfo,
 	if (resultRelInfo->ri_PartitionRoot)
 	{
 		TupleDesc	old_tupdesc;
-		AttrNumber *map;
+		AttrMap	   *map;
 
 		root_relid = RelationGetRelid(resultRelInfo->ri_PartitionRoot);
 		tupdesc = RelationGetDescr(resultRelInfo->ri_PartitionRoot);
@@ -1929,7 +1929,7 @@ ExecConstraints(ResultRelInfo *resultRelInfo,
 				 */
 				if (resultRelInfo->ri_PartitionRoot)
 				{
-					AttrNumber *map;
+					AttrMap *map;
 
 					rel = resultRelInfo->ri_PartitionRoot;
 					tupdesc = RelationGetDescr(rel);
@@ -1978,7 +1978,7 @@ ExecConstraints(ResultRelInfo *resultRelInfo,
 			if (resultRelInfo->ri_PartitionRoot)
 			{
 				TupleDesc	old_tupdesc = RelationGetDescr(rel);
-				AttrNumber *map;
+				AttrMap *map;
 
 				rel = resultRelInfo->ri_PartitionRoot;
 				tupdesc = RelationGetDescr(rel);
@@ -2085,7 +2085,7 @@ ExecWithCheckOptions(WCOKind kind, ResultRelInfo *resultRelInfo,
 					if (resultRelInfo->ri_PartitionRoot)
 					{
 						TupleDesc	old_tupdesc = RelationGetDescr(rel);
-						AttrNumber *map;
+						AttrMap *map;
 
 						rel = resultRelInfo->ri_PartitionRoot;
 						tupdesc = RelationGetDescr(rel);
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index d23f292cb0..af5e89bec8 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -143,7 +143,7 @@ typedef struct PartitionDispatchData
 	List	   *keystate;		/* list of ExprState */
 	PartitionDesc partdesc;
 	TupleTableSlot *tupslot;
-	AttrNumber *tupmap;
+	AttrMap	   *tupmap;
 	int			indexes[FLEXIBLE_ARRAY_MEMBER];
 }			PartitionDispatchData;
 
@@ -298,7 +298,7 @@ ExecFindPartition(ModifyTableState *mtstate,
 	dispatch = pd[0];
 	while (true)
 	{
-		AttrNumber *map = dispatch->tupmap;
+		AttrMap	   *map = dispatch->tupmap;
 		int			partidx = -1;
 
 		CHECK_FOR_INTERRUPTS();
@@ -511,7 +511,7 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 	Relation	firstResultRel = mtstate->resultRelInfo[0].ri_RelationDesc;
 	ResultRelInfo *leaf_part_rri;
 	MemoryContext oldcxt;
-	AttrNumber *part_attnos = NULL;
+	AttrMap	   *part_attmap = NULL;
 	bool		found_whole_row;
 
 	oldcxt = MemoryContextSwitchTo(proute->memcxt);
@@ -584,14 +584,13 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		/*
 		 * Convert Vars in it to contain this partition's attribute numbers.
 		 */
-		part_attnos =
+		part_attmap =
 			convert_tuples_by_name_map(RelationGetDescr(partrel),
 									   RelationGetDescr(firstResultRel));
 		wcoList = (List *)
 			map_variable_attnos((Node *) wcoList,
 								firstVarno, 0,
-								part_attnos,
-								RelationGetDescr(firstResultRel)->natts,
+								part_attmap,
 								RelationGetForm(partrel)->reltype,
 								&found_whole_row);
 		/* We ignore the value of found_whole_row. */
@@ -642,15 +641,14 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		/*
 		 * Convert Vars in it to contain this partition's attribute numbers.
 		 */
-		if (part_attnos == NULL)
-			part_attnos =
+		if (part_attmap == NULL)
+			part_attmap =
 				convert_tuples_by_name_map(RelationGetDescr(partrel),
 										   RelationGetDescr(firstResultRel));
 		returningList = (List *)
 			map_variable_attnos((Node *) returningList,
 								firstVarno, 0,
-								part_attnos,
-								RelationGetDescr(firstResultRel)->natts,
+								part_attmap,
 								RelationGetForm(partrel)->reltype,
 								&found_whole_row);
 		/* We ignore the value of found_whole_row. */
@@ -785,23 +783,21 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				 * target relation (firstVarno).
 				 */
 				onconflset = (List *) copyObject((Node *) node->onConflictSet);
-				if (part_attnos == NULL)
-					part_attnos =
+				if (part_attmap == NULL)
+					part_attmap =
 						convert_tuples_by_name_map(RelationGetDescr(partrel),
 												   RelationGetDescr(firstResultRel));
 				onconflset = (List *)
 					map_variable_attnos((Node *) onconflset,
 										INNER_VAR, 0,
-										part_attnos,
-										RelationGetDescr(firstResultRel)->natts,
+										part_attmap,
 										RelationGetForm(partrel)->reltype,
 										&found_whole_row);
 				/* We ignore the value of found_whole_row. */
 				onconflset = (List *)
 					map_variable_attnos((Node *) onconflset,
 										firstVarno, 0,
-										part_attnos,
-										RelationGetDescr(firstResultRel)->natts,
+										part_attmap,
 										RelationGetForm(partrel)->reltype,
 										&found_whole_row);
 				/* We ignore the value of found_whole_row. */
@@ -835,16 +831,14 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 					clause = (List *)
 						map_variable_attnos((Node *) clause,
 											INNER_VAR, 0,
-											part_attnos,
-											RelationGetDescr(firstResultRel)->natts,
+											part_attmap,
 											RelationGetForm(partrel)->reltype,
 											&found_whole_row);
 					/* We ignore the value of found_whole_row. */
 					clause = (List *)
 						map_variable_attnos((Node *) clause,
 											firstVarno, 0,
-											part_attnos,
-											RelationGetDescr(firstResultRel)->natts,
+											part_attmap,
 											RelationGetForm(partrel)->reltype,
 											&found_whole_row);
 					/* We ignore the value of found_whole_row. */
@@ -1434,15 +1428,16 @@ adjust_partition_tlist(List *tlist, TupleConversionMap *map)
 {
 	List	   *new_tlist = NIL;
 	TupleDesc	tupdesc = map->outdesc;
-	AttrNumber *attrMap = map->attrMap;
+	AttrMap	   *attrMap = map->attrMap;
 	AttrNumber	attrno;
 
+	Assert(tupdesc->natts == attrMap->maplen);
 	for (attrno = 1; attrno <= tupdesc->natts; attrno++)
 	{
 		Form_pg_attribute att_tup = TupleDescAttr(tupdesc, attrno - 1);
 		TargetEntry *tle;
 
-		if (attrMap[attrno - 1] != InvalidAttrNumber)
+		if (attrMap->attnums[attrno - 1] != InvalidAttrNumber)
 		{
 			Assert(!att_tup->attisdropped);
 
@@ -1450,7 +1445,7 @@ adjust_partition_tlist(List *tlist, TupleConversionMap *map)
 			 * Use the corresponding entry from the parent's tlist, adjusting
 			 * the resno the match the partition's attno.
 			 */
-			tle = (TargetEntry *) list_nth(tlist, attrMap[attrno - 1] - 1);
+			tle = (TargetEntry *) list_nth(tlist, attrMap->attnums[attrno - 1] - 1);
 			tle->resno = attrno;
 		}
 		else
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index ee47547624..9c5462aef6 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -917,7 +917,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 	Relation	relation;
 	TupleDesc	tupleDesc;
 	TupleConstr *constr;
-	AttrNumber *attmap;
+	AttrMap	   *attmap;
 	AclResult	aclresult;
 	char	   *comment;
 	ParseCallbackState pcbstate;
@@ -974,7 +974,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 	 * since dropped columns in the source table aren't copied, so the new
 	 * table can have different column numbers.
 	 */
-	attmap = (AttrNumber *) palloc0(sizeof(AttrNumber) * tupleDesc->natts);
+	attmap = make_attrmap(tupleDesc->natts);
 
 	/*
 	 * Insert the copied attributes into the cxt for the new table definition.
@@ -1020,7 +1020,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 		 */
 		cxt->columns = lappend(cxt->columns, def);
 
-		attmap[parent_attno - 1] = list_length(cxt->columns);
+		attmap->attnums[parent_attno - 1] = list_length(cxt->columns);
 
 		/*
 		 * Copy default, if present and it should be copied.  We have separate
@@ -1051,7 +1051,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 
 			def->cooked_default = map_variable_attnos(this_default,
 													  1, 0,
-													  attmap, tupleDesc->natts,
+													  attmap,
 													  InvalidOid, &found_whole_row);
 
 			/*
@@ -1134,7 +1134,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 
 			ccbin_node = map_variable_attnos(stringToNode(ccbin),
 											 1, 0,
-											 attmap, tupleDesc->natts,
+											 attmap,
 											 InvalidOid, &found_whole_row);
 
 			/*
@@ -1200,7 +1200,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 			/* Build CREATE INDEX statement to recreate the parent_index */
 			index_stmt = generateClonedIndexStmt(cxt->relation,
 												 parent_index,
-												 attmap, tupleDesc->natts,
+												 attmap,
 												 NULL);
 
 			/* Copy comment on index, if requested */
@@ -1332,7 +1332,7 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
  */
 IndexStmt *
 generateClonedIndexStmt(RangeVar *heapRel, Relation source_idx,
-						const AttrNumber *attmap, int attmap_length,
+						const AttrMap *attmap,
 						Oid *constraintOid)
 {
 	Oid			source_relid = RelationGetRelid(source_idx);
@@ -1552,7 +1552,7 @@ generateClonedIndexStmt(RangeVar *heapRel, Relation source_idx,
 			/* Adjust Vars to match new table's column numbering */
 			indexkey = map_variable_attnos(indexkey,
 										   1, 0,
-										   attmap, attmap_length,
+										   attmap,
 										   InvalidOid, &found_whole_row);
 
 			/* As in transformTableLikeClause, reject whole-row variables */
@@ -1659,7 +1659,7 @@ generateClonedIndexStmt(RangeVar *heapRel, Relation source_idx,
 		/* Adjust Vars to match new table's column numbering */
 		pred_tree = map_variable_attnos(pred_tree,
 										1, 0,
-										attmap, attmap_length,
+										attmap,
 										InvalidOid, &found_whole_row);
 
 		/* As in transformTableLikeClause, reject whole-row variables */
diff --git a/src/backend/replication/logical/relation.c b/src/backend/replication/logical/relation.c
index b386f8460d..f38c5b3ea4 100644
--- a/src/backend/replication/logical/relation.c
+++ b/src/backend/replication/logical/relation.c
@@ -267,7 +267,7 @@ logicalrep_rel_open(LogicalRepRelId remoteid, LOCKMODE lockmode)
 		 */
 		desc = RelationGetDescr(entry->localrel);
 		oldctx = MemoryContextSwitchTo(LogicalRepRelMapContext);
-		entry->attrmap = palloc(desc->natts * sizeof(AttrNumber));
+		entry->attrmap = make_attrmap(desc->natts);
 		MemoryContextSwitchTo(oldctx);
 
 		found = 0;
@@ -278,14 +278,14 @@ logicalrep_rel_open(LogicalRepRelId remoteid, LOCKMODE lockmode)
 
 			if (attr->attisdropped || attr->attgenerated)
 			{
-				entry->attrmap[i] = -1;
+				entry->attrmap->attnums[i] = -1;
 				continue;
 			}
 
 			attnum = logicalrep_rel_att_by_name(remoterel,
 												NameStr(attr->attname));
 
-			entry->attrmap[i] = attnum;
+			entry->attrmap->attnums[i] = attnum;
 			if (attnum >= 0)
 				found++;
 		}
@@ -340,8 +340,8 @@ logicalrep_rel_open(LogicalRepRelId remoteid, LOCKMODE lockmode)
 
 			attnum = AttrNumberGetAttrOffset(attnum);
 
-			if (entry->attrmap[attnum] < 0 ||
-				!bms_is_member(entry->attrmap[attnum], remoterel->attkeys))
+			if (entry->attrmap->attnums[attnum] < 0 ||
+				!bms_is_member(entry->attrmap->attnums[attnum], remoterel->attkeys))
 			{
 				entry->updatable = false;
 				break;
diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index ff62303638..1a91c60c17 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -232,6 +232,7 @@ slot_fill_defaults(LogicalRepRelMapEntry *rel, EState *estate,
 	defmap = (int *) palloc(num_phys_attrs * sizeof(int));
 	defexprs = (ExprState **) palloc(num_phys_attrs * sizeof(ExprState *));
 
+	Assert(rel->attrmap->maplen == num_phys_attrs);
 	for (attnum = 0; attnum < num_phys_attrs; attnum++)
 	{
 		Expr	   *defexpr;
@@ -239,7 +240,7 @@ slot_fill_defaults(LogicalRepRelMapEntry *rel, EState *estate,
 		if (TupleDescAttr(desc, attnum)->attisdropped || TupleDescAttr(desc, attnum)->attgenerated)
 			continue;
 
-		if (rel->attrmap[attnum] >= 0)
+		if (rel->attrmap->attnums[attnum] >= 0)
 			continue;
 
 		defexpr = (Expr *) build_column_default(rel->localrel, attnum + 1);
@@ -321,10 +322,11 @@ slot_store_cstrings(TupleTableSlot *slot, LogicalRepRelMapEntry *rel,
 	error_context_stack = &errcallback;
 
 	/* Call the "in" function for each non-dropped attribute */
+	Assert(natts == rel->attrmap->maplen);
 	for (i = 0; i < natts; i++)
 	{
 		Form_pg_attribute att = TupleDescAttr(slot->tts_tupleDescriptor, i);
-		int			remoteattnum = rel->attrmap[i];
+		int			remoteattnum = rel->attrmap->attnums[i];
 
 		if (!att->attisdropped && remoteattnum >= 0 &&
 			values[remoteattnum] != NULL)
@@ -390,10 +392,11 @@ slot_modify_cstrings(TupleTableSlot *slot, LogicalRepRelMapEntry *rel,
 	error_context_stack = &errcallback;
 
 	/* Call the "in" function for each replaced attribute */
+	Assert(natts == rel->attrmap->maplen);
 	for (i = 0; i < natts; i++)
 	{
 		Form_pg_attribute att = TupleDescAttr(slot->tts_tupleDescriptor, i);
-		int			remoteattnum = rel->attrmap[i];
+		int			remoteattnum = rel->attrmap->attnums[i];
 
 		if (remoteattnum < 0)
 			continue;
diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index 93508c2a87..12f7cadf3b 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -1221,8 +1221,7 @@ typedef struct
 {
 	int			target_varno;	/* RTE index to search for */
 	int			sublevels_up;	/* (current) nesting depth */
-	const AttrNumber *attno_map;	/* map array for user attnos */
-	int			map_length;		/* number of entries in attno_map[] */
+	const AttrMap *attno_map;	/* map array for user attnos */
 	Oid			to_rowtype;		/* change whole-row Vars to this type */
 	bool	   *found_whole_row;	/* output flag */
 } map_variable_attnos_context;
@@ -1249,11 +1248,11 @@ map_variable_attnos_mutator(Node *node,
 			if (attno > 0)
 			{
 				/* user-defined column, replace attno */
-				if (attno > context->map_length ||
-					context->attno_map[attno - 1] == 0)
+				if (attno > context->attno_map->maplen ||
+					context->attno_map->attnums[attno - 1] == 0)
 					elog(ERROR, "unexpected varattno %d in expression to be mapped",
 						 attno);
-				newvar->varattno = newvar->varoattno = context->attno_map[attno - 1];
+				newvar->varattno = newvar->varoattno = context->attno_map->attnums[attno - 1];
 			}
 			else if (attno == 0)
 			{
@@ -1350,7 +1349,7 @@ map_variable_attnos_mutator(Node *node,
 Node *
 map_variable_attnos(Node *node,
 					int target_varno, int sublevels_up,
-					const AttrNumber *attno_map, int map_length,
+					const AttrMap *attno_map,
 					Oid to_rowtype, bool *found_whole_row)
 {
 	map_variable_attnos_context context;
@@ -1358,7 +1357,6 @@ map_variable_attnos(Node *node,
 	context.target_varno = target_varno;
 	context.sublevels_up = sublevels_up;
 	context.attno_map = attno_map;
-	context.map_length = map_length;
 	context.to_rowtype = to_rowtype;
 	context.found_whole_row = found_whole_row;
 
diff --git a/src/include/access/attmap.h b/src/include/access/attmap.h
new file mode 100644
index 0000000000..8e4882f096
--- /dev/null
+++ b/src/include/access/attmap.h
@@ -0,0 +1,42 @@
+/*-------------------------------------------------------------------------
+ *
+ * attnum.h
+ *	  Definitions for PostgreSQL attribute mappings
+ *
+ *
+ * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/access/attmap.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ATTMAP_H
+#define ATTMAP_H
+
+#include "access/attnum.h"
+
+/*
+ * Attribute mapping structure
+ *
+ * An attribute mapping tracks the relationship of a child relation and
+ * its parent for inheritance and partitions.  This is used mainly for
+ * cloned object creations (indexes, foreign keys, etc.) when creating
+ * an inherited child relation, and for runtime-execution attribute
+ * mapping.
+ *
+ * Dropped attributes are marked with 0 and the length of the map is set
+ * to be the number of attributes of the parent, which takes into account
+ * its dropped attributes.
+ */
+typedef struct AttrMap
+{
+	AttrNumber	   *attnums;
+	int				maplen;
+} AttrMap;
+
+/* utility routines to manipulate attribute maps */
+extern AttrMap *make_attrmap(int maplen);
+extern void		free_attrmap(AttrMap *map);
+
+#endif							/* ATTMAP_H */
diff --git a/src/include/access/tupconvert.h b/src/include/access/tupconvert.h
index 6d095f8e0d..f48cba967d 100644
--- a/src/include/access/tupconvert.h
+++ b/src/include/access/tupconvert.h
@@ -14,6 +14,7 @@
 #ifndef TUPCONVERT_H
 #define TUPCONVERT_H
 
+#include "access/attmap.h"
 #include "access/htup.h"
 #include "access/tupdesc.h"
 #include "executor/tuptable.h"
@@ -23,7 +24,7 @@ typedef struct TupleConversionMap
 {
 	TupleDesc	indesc;			/* tupdesc for source rowtype */
 	TupleDesc	outdesc;		/* tupdesc for result rowtype */
-	AttrNumber *attrMap;		/* indexes of input fields, or 0 for null */
+	AttrMap    *attrMap;		/* indexes of input fields, or 0 for null */
 	Datum	   *invalues;		/* workspace for deconstructing source */
 	bool	   *inisnull;
 	Datum	   *outvalues;		/* workspace for constructing result */
@@ -38,14 +39,15 @@ extern TupleConversionMap *convert_tuples_by_position(TupleDesc indesc,
 extern TupleConversionMap *convert_tuples_by_name(TupleDesc indesc,
 												  TupleDesc outdesc);
 
-extern AttrNumber *convert_tuples_by_name_map(TupleDesc indesc,
-											  TupleDesc outdesc);
-extern AttrNumber *convert_tuples_by_name_map_if_req(TupleDesc indesc,
-													 TupleDesc outdesc);
+extern AttrMap *convert_tuples_by_name_map(TupleDesc indesc,
+										   TupleDesc outdesc);
+extern AttrMap *convert_tuples_by_name_map_if_req(TupleDesc indesc,
+												  TupleDesc outdesc);
 
 extern HeapTuple execute_attr_map_tuple(HeapTuple tuple, TupleConversionMap *map);
-extern TupleTableSlot *execute_attr_map_slot(AttrNumber *attrMap,
-											 TupleTableSlot *in_slot, TupleTableSlot *out_slot);
+extern TupleTableSlot *execute_attr_map_slot(AttrMap *attrMap,
+											 TupleTableSlot *in_slot,
+											 TupleTableSlot *out_slot);
 
 extern void free_conversion_map(TupleConversionMap *map);
 
diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h
index 1113d25b2d..f42aa53128 100644
--- a/src/include/catalog/index.h
+++ b/src/include/catalog/index.h
@@ -109,7 +109,7 @@ extern IndexInfo *BuildIndexInfo(Relation index);
 extern bool CompareIndexInfo(IndexInfo *info1, IndexInfo *info2,
 							 Oid *collations1, Oid *collations2,
 							 Oid *opfamilies1, Oid *opfamilies2,
-							 AttrNumber *attmap, int maplen);
+							 AttrMap *attmap);
 
 extern void BuildSpeculativeIndexInfo(Relation index, IndexInfo *ii);
 
diff --git a/src/include/parser/parse_utilcmd.h b/src/include/parser/parse_utilcmd.h
index 1348064ad0..08dd0ce4ca 100644
--- a/src/include/parser/parse_utilcmd.h
+++ b/src/include/parser/parse_utilcmd.h
@@ -16,6 +16,7 @@
 
 #include "parser/parse_node.h"
 
+typedef struct AttrMap AttrMap;
 
 extern List *transformCreateStmt(CreateStmt *stmt, const char *queryString);
 extern List *transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
@@ -29,7 +30,7 @@ extern PartitionBoundSpec *transformPartitionBound(ParseState *pstate, Relation
 												   PartitionBoundSpec *spec);
 extern IndexStmt *generateClonedIndexStmt(RangeVar *heapRel,
 										  Relation source_idx,
-										  const AttrNumber *attmap, int attmap_length,
+										  const AttrMap *attmap,
 										  Oid *constraintOid);
 
 #endif							/* PARSE_UTILCMD_H */
diff --git a/src/include/replication/logicalrelation.h b/src/include/replication/logicalrelation.h
index 2642a3f94e..f167d4e59b 100644
--- a/src/include/replication/logicalrelation.h
+++ b/src/include/replication/logicalrelation.h
@@ -21,7 +21,7 @@ typedef struct LogicalRepRelMapEntry
 	/* Mapping to local relation, filled as needed. */
 	Oid			localreloid;	/* local relation id */
 	Relation	localrel;		/* relcache entry */
-	AttrNumber *attrmap;		/* map of local attributes to remote ones */
+	AttrMap	   *attrmap;		/* map of local attributes to remote ones */
 	bool		updatable;		/* Can apply updates/deletes? */
 
 	/* Sync state. */
diff --git a/src/include/rewrite/rewriteManip.h b/src/include/rewrite/rewriteManip.h
index 8d8fd17e41..634cdc235d 100644
--- a/src/include/rewrite/rewriteManip.h
+++ b/src/include/rewrite/rewriteManip.h
@@ -17,6 +17,7 @@
 #include "nodes/parsenodes.h"
 
 
+typedef struct AttrMap AttrMap;
 typedef struct replace_rte_variables_context replace_rte_variables_context;
 
 typedef Node *(*replace_rte_variables_callback) (Var *var,
@@ -71,7 +72,7 @@ extern Node *replace_rte_variables_mutator(Node *node,
 
 extern Node *map_variable_attnos(Node *node,
 								 int target_varno, int sublevels_up,
-								 const AttrNumber *attno_map, int map_length,
+								 const AttrMap *attno_map,
 								 Oid to_rowtype, bool *found_whole_row);
 
 extern Node *ReplaceVarsFromTargetList(Node *node,
-- 
2.24.0