Change tupledesc->attrs[n] to TupleDescAttr(tupledesc, n).

This is a mechanical change in preparation for a later commit that
will change the layout of TupleDesc.  Introducing a macro to abstract
the details of where attributes are stored will allow us to change
that in separate step and revise it in future.

Author: Thomas Munro, editorialized by Andres Freund
Reviewed-By: Andres Freund
Discussion: https://postgr.es/m/CAEepm=0ZtQ-SpsgCyzzYpsXS6e=kZWqk3g5Ygn3MDV7A8dabUA@mail.gmail.com

9 files changed, 80 insertions, 58 deletions

diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index 2b638271b3d..fbad13ea94f 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -871,7 +871,7 @@ compute_index_stats(Relation onerel, double totalrows,
 static VacAttrStats *
 examine_attribute(Relation onerel, int attnum, Node *index_expr)
 {
-	Form_pg_attribute attr = onerel->rd_att->attrs[attnum - 1];
+	Form_pg_attribute attr = TupleDescAttr(onerel->rd_att, attnum - 1);
 	HeapTuple	typtuple;
 	VacAttrStats *stats;
 	int			i;
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index f51f8b94922..48f1e6e2add 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -1714,7 +1714,7 @@ reform_and_rewrite_tuple(HeapTuple tuple,
 	/* Be sure to null out any dropped columns */
 	for (i = 0; i < newTupDesc->natts; i++)
 	{
-		if (newTupDesc->attrs[i]->attisdropped)
+		if (TupleDescAttr(newTupDesc, i)->attisdropped)
 			isnull[i] = true;
 	}
 
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 375a25fbcf8..cfa3f059c2a 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -1583,12 +1583,13 @@ BeginCopy(ParseState *pstate,
 		foreach(cur, attnums)
 		{
 			int			attnum = lfirst_int(cur);
+			Form_pg_attribute attr = TupleDescAttr(tupDesc, attnum - 1);
 
 			if (!list_member_int(cstate->attnumlist, attnum))
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 						 errmsg("FORCE_QUOTE column \"%s\" not referenced by COPY",
-								NameStr(tupDesc->attrs[attnum - 1]->attname))));
+								NameStr(attr->attname))));
 			cstate->force_quote_flags[attnum - 1] = true;
 		}
 	}
@@ -1605,12 +1606,13 @@ BeginCopy(ParseState *pstate,
 		foreach(cur, attnums)
 		{
 			int			attnum = lfirst_int(cur);
+			Form_pg_attribute attr = TupleDescAttr(tupDesc, attnum - 1);
 
 			if (!list_member_int(cstate->attnumlist, attnum))
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 						 errmsg("FORCE_NOT_NULL column \"%s\" not referenced by COPY",
-								NameStr(tupDesc->attrs[attnum - 1]->attname))));
+								NameStr(attr->attname))));
 			cstate->force_notnull_flags[attnum - 1] = true;
 		}
 	}
@@ -1627,12 +1629,13 @@ BeginCopy(ParseState *pstate,
 		foreach(cur, attnums)
 		{
 			int			attnum = lfirst_int(cur);
+			Form_pg_attribute attr = TupleDescAttr(tupDesc, attnum - 1);
 
 			if (!list_member_int(cstate->attnumlist, attnum))
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 						 errmsg("FORCE_NULL column \"%s\" not referenced by COPY",
-								NameStr(tupDesc->attrs[attnum - 1]->attname))));
+								NameStr(attr->attname))));
 			cstate->force_null_flags[attnum - 1] = true;
 		}
 	}
@@ -1650,12 +1653,13 @@ BeginCopy(ParseState *pstate,
 		foreach(cur, attnums)
 		{
 			int			attnum = lfirst_int(cur);
+			Form_pg_attribute attr = TupleDescAttr(tupDesc, attnum - 1);
 
 			if (!list_member_int(cstate->attnumlist, attnum))
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 						 errmsg_internal("selected column \"%s\" not referenced by COPY",
-										 NameStr(tupDesc->attrs[attnum - 1]->attname))));
+										 NameStr(attr->attname))));
 			cstate->convert_select_flags[attnum - 1] = true;
 		}
 	}
@@ -1919,7 +1923,6 @@ CopyTo(CopyState cstate)
 {
 	TupleDesc	tupDesc;
 	int			num_phys_attrs;
-	Form_pg_attribute *attr;
 	ListCell   *cur;
 	uint64		processed;
 
@@ -1927,7 +1930,6 @@ CopyTo(CopyState cstate)
 		tupDesc = RelationGetDescr(cstate->rel);
 	else
 		tupDesc = cstate->queryDesc->tupDesc;
-	attr = tupDesc->attrs;
 	num_phys_attrs = tupDesc->natts;
 	cstate->null_print_client = cstate->null_print; /* default */
 
@@ -1941,13 +1943,14 @@ CopyTo(CopyState cstate)
 		int			attnum = lfirst_int(cur);
 		Oid			out_func_oid;
 		bool		isvarlena;
+		Form_pg_attribute attr = TupleDescAttr(tupDesc, attnum - 1);
 
 		if (cstate->binary)
-			getTypeBinaryOutputInfo(attr[attnum - 1]->atttypid,
+			getTypeBinaryOutputInfo(attr->atttypid,
 									&out_func_oid,
 									&isvarlena);
 		else
-			getTypeOutputInfo(attr[attnum - 1]->atttypid,
+			getTypeOutputInfo(attr->atttypid,
 							  &out_func_oid,
 							  &isvarlena);
 		fmgr_info(out_func_oid, &cstate->out_functions[attnum - 1]);
@@ -2004,7 +2007,7 @@ CopyTo(CopyState cstate)
 					CopySendChar(cstate, cstate->delim[0]);
 				hdr_delim = true;
 
-				colname = NameStr(attr[attnum - 1]->attname);
+				colname = NameStr(TupleDescAttr(tupDesc, attnum - 1)->attname);
 
 				CopyAttributeOutCSV(cstate, colname, false,
 									list_length(cstate->attnumlist) == 1);
@@ -2969,7 +2972,6 @@ BeginCopyFrom(ParseState *pstate,
 	CopyState	cstate;
 	bool		pipe = (filename == NULL);
 	TupleDesc	tupDesc;
-	Form_pg_attribute *attr;
 	AttrNumber	num_phys_attrs,
 				num_defaults;
 	FmgrInfo   *in_functions;
@@ -3004,7 +3006,6 @@ BeginCopyFrom(ParseState *pstate,
 		cstate->range_table = pstate->p_rtable;
 
 	tupDesc = RelationGetDescr(cstate->rel);
-	attr = tupDesc->attrs;
 	num_phys_attrs = tupDesc->natts;
 	num_defaults = 0;
 	volatile_defexprs = false;
@@ -3022,16 +3023,18 @@ BeginCopyFrom(ParseState *pstate,
 
 	for (attnum = 1; attnum <= num_phys_attrs; attnum++)
 	{
+		Form_pg_attribute att = TupleDescAttr(tupDesc, attnum - 1);
+
 		/* We don't need info for dropped attributes */
-		if (attr[attnum - 1]->attisdropped)
+		if (att->attisdropped)
 			continue;
 
 		/* Fetch the input function and typioparam info */
 		if (cstate->binary)
-			getTypeBinaryInputInfo(attr[attnum - 1]->atttypid,
+			getTypeBinaryInputInfo(att->atttypid,
 								   &in_func_oid, &typioparams[attnum - 1]);
 		else
-			getTypeInputInfo(attr[attnum - 1]->atttypid,
+			getTypeInputInfo(att->atttypid,
 							 &in_func_oid, &typioparams[attnum - 1]);
 		fmgr_info(in_func_oid, &in_functions[attnum - 1]);
 
@@ -3273,7 +3276,6 @@ NextCopyFrom(CopyState cstate, ExprContext *econtext,
 			 Datum *values, bool *nulls, Oid *tupleOid)
 {
 	TupleDesc	tupDesc;
-	Form_pg_attribute *attr;
 	AttrNumber	num_phys_attrs,
 				attr_count,
 				num_defaults = cstate->num_defaults;
@@ -3287,7 +3289,6 @@ NextCopyFrom(CopyState cstate, ExprContext *econtext,
 	ExprState **defexprs = cstate->defexprs;
 
 	tupDesc = RelationGetDescr(cstate->rel);
-	attr = tupDesc->attrs;
 	num_phys_attrs = tupDesc->natts;
 	attr_count = list_length(cstate->attnumlist);
 	nfields = file_has_oids ? (attr_count + 1) : attr_count;
@@ -3349,12 +3350,13 @@ NextCopyFrom(CopyState cstate, ExprContext *econtext,
 		{
 			int			attnum = lfirst_int(cur);
 			int			m = attnum - 1;
+			Form_pg_attribute att = TupleDescAttr(tupDesc, m);
 
 			if (fieldno >= fldct)
 				ereport(ERROR,
 						(errcode(ERRCODE_BAD_COPY_FILE_FORMAT),
 						 errmsg("missing data for column \"%s\"",
-								NameStr(attr[m]->attname))));
+								NameStr(att->attname))));
 			string = field_strings[fieldno++];
 
 			if (cstate->convert_select_flags &&
@@ -3388,12 +3390,12 @@ NextCopyFrom(CopyState cstate, ExprContext *econtext,
 				}
 			}
 
-			cstate->cur_attname = NameStr(attr[m]->attname);
+			cstate->cur_attname = NameStr(att->attname);
 			cstate->cur_attval = string;
 			values[m] = InputFunctionCall(&in_functions[m],
 										  string,
 										  typioparams[m],
-										  attr[m]->atttypmod);
+										  att->atttypmod);
 			if (string != NULL)
 				nulls[m] = false;
 			cstate->cur_attname = NULL;
@@ -3472,14 +3474,15 @@ NextCopyFrom(CopyState cstate, ExprContext *econtext,
 		{
 			int			attnum = lfirst_int(cur);
 			int			m = attnum - 1;
+			Form_pg_attribute att = TupleDescAttr(tupDesc, m);
 
-			cstate->cur_attname = NameStr(attr[m]->attname);
+			cstate->cur_attname = NameStr(att->attname);
 			i++;
 			values[m] = CopyReadBinaryAttribute(cstate,
 												i,
 												&in_functions[m],
 												typioparams[m],
-												attr[m]->atttypmod,
+												att->atttypmod,
 												&nulls[m]);
 			cstate->cur_attname = NULL;
 		}
@@ -4709,13 +4712,12 @@ CopyGetAttnums(TupleDesc tupDesc, Relation rel, List *attnamelist)
 	if (attnamelist == NIL)
 	{
 		/* Generate default column list */
-		Form_pg_attribute *attr = tupDesc->attrs;
 		int			attr_count = tupDesc->natts;
 		int			i;
 
 		for (i = 0; i < attr_count; i++)
 		{
-			if (attr[i]->attisdropped)
+			if (TupleDescAttr(tupDesc, i)->attisdropped)
 				continue;
 			attnums = lappend_int(attnums, i + 1);
 		}
@@ -4735,11 +4737,13 @@ CopyGetAttnums(TupleDesc tupDesc, Relation rel, List *attnamelist)
 			attnum = InvalidAttrNumber;
 			for (i = 0; i < tupDesc->natts; i++)
 			{
-				if (tupDesc->attrs[i]->attisdropped)
+				Form_pg_attribute att = TupleDescAttr(tupDesc, i);
+
+				if (att->attisdropped)
 					continue;
-				if (namestrcmp(&(tupDesc->attrs[i]->attname), name) == 0)
+				if (namestrcmp(&(att->attname), name) == 0)
 				{
-					attnum = tupDesc->attrs[i]->attnum;
+					attnum = att->attnum;
 					break;
 				}
 			}
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 97f9c55d6e7..e60210cb24b 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -468,7 +468,7 @@ intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
 	lc = list_head(into->colNames);
 	for (attnum = 0; attnum < typeinfo->natts; attnum++)
 	{
-		Form_pg_attribute attribute = typeinfo->attrs[attnum];
+		Form_pg_attribute attribute = TupleDescAttr(typeinfo, attnum);
 		ColumnDef  *col;
 		char	   *colname;
 
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 620704ec490..b61aaac2842 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -242,7 +242,7 @@ CheckIndexCompatible(Oid oldId,
 	for (i = 0; i < old_natts; i++)
 	{
 		if (IsPolymorphicType(get_opclass_input_type(classObjectId[i])) &&
-			irel->rd_att->attrs[i]->atttypid != typeObjectId[i])
+			TupleDescAttr(irel->rd_att, i)->atttypid != typeObjectId[i])
 		{
 			ret = false;
 			break;
@@ -270,7 +270,7 @@ CheckIndexCompatible(Oid oldId,
 
 				op_input_types(indexInfo->ii_ExclusionOps[i], &left, &right);
 				if ((IsPolymorphicType(left) || IsPolymorphicType(right)) &&
-					irel->rd_att->attrs[i]->atttypid != typeObjectId[i])
+					TupleDescAttr(irel->rd_att, i)->atttypid != typeObjectId[i])
 				{
 					ret = false;
 					break;
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 7d57f97442e..d2e0376511a 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -727,6 +727,7 @@ refresh_by_match_merge(Oid matviewOid, Oid tempOid, Oid relowner,
 			for (i = 0; i < numatts; i++)
 			{
 				int			attnum = indexStruct->indkey.values[i];
+				Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
 				Oid			type;
 				Oid			op;
 				const char *colname;
@@ -745,7 +746,7 @@ refresh_by_match_merge(Oid matviewOid, Oid tempOid, Oid relowner,
 				if (foundUniqueIndex)
 					appendStringInfoString(&querybuf, " AND ");
 
-				colname = quote_identifier(NameStr((tupdesc->attrs[attnum - 1])->attname));
+				colname = quote_identifier(NameStr(attr->attname));
 				appendStringInfo(&querybuf, "newdata.%s ", colname);
 				type = attnumTypeId(matviewRel, attnum);
 				op = lookup_type_cache(type, TYPECACHE_EQ_OPR)->eq_opr;
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 83cb4601641..0f08245a677 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -685,8 +685,10 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 	foreach(listptr, stmt->tableElts)
 	{
 		ColumnDef  *colDef = lfirst(listptr);
+		Form_pg_attribute attr;
 
 		attnum++;
+		attr = TupleDescAttr(descriptor, attnum - 1);
 
 		if (colDef->raw_default != NULL)
 		{
@@ -698,7 +700,7 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			rawEnt->attnum = attnum;
 			rawEnt->raw_default = colDef->raw_default;
 			rawDefaults = lappend(rawDefaults, rawEnt);
-			descriptor->attrs[attnum - 1]->atthasdef = true;
+			attr->atthasdef = true;
 		}
 		else if (colDef->cooked_default != NULL)
 		{
@@ -715,11 +717,11 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			cooked->inhcount = 0;	/* ditto */
 			cooked->is_no_inherit = false;
 			cookedDefaults = lappend(cookedDefaults, cooked);
-			descriptor->attrs[attnum - 1]->atthasdef = true;
+			attr->atthasdef = true;
 		}
 
 		if (colDef->identity)
-			descriptor->attrs[attnum - 1]->attidentity = colDef->identity;
+			attr->attidentity = colDef->identity;
 	}
 
 	/*
@@ -1833,7 +1835,8 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		for (parent_attno = 1; parent_attno <= tupleDesc->natts;
 			 parent_attno++)
 		{
-			Form_pg_attribute attribute = tupleDesc->attrs[parent_attno - 1];
+			Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
+														parent_attno - 1);
 			char	   *attributeName = NameStr(attribute->attname);
 			int			exist_attno;
 			ColumnDef  *def;
@@ -4417,8 +4420,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 		 */
 		for (i = 0; i < newTupDesc->natts; i++)
 		{
-			if (newTupDesc->attrs[i]->attnotnull &&
-				!newTupDesc->attrs[i]->attisdropped)
+			Form_pg_attribute attr = TupleDescAttr(newTupDesc, i);
+
+			if (attr->attnotnull && !attr->attisdropped)
 				notnull_attrs = lappend_int(notnull_attrs, i);
 		}
 		if (notnull_attrs)
@@ -4482,7 +4486,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 		 */
 		for (i = 0; i < newTupDesc->natts; i++)
 		{
-			if (newTupDesc->attrs[i]->attisdropped)
+			if (TupleDescAttr(newTupDesc, i)->attisdropped)
 				dropped_attrs = lappend_int(dropped_attrs, i);
 		}
 
@@ -4556,11 +4560,15 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 				int			attn = lfirst_int(l);
 
 				if (heap_attisnull(tuple, attn + 1))
+				{
+					Form_pg_attribute attr = TupleDescAttr(newTupDesc, attn);
+
 					ereport(ERROR,
 							(errcode(ERRCODE_NOT_NULL_VIOLATION),
 							 errmsg("column \"%s\" contains null values",
-									NameStr(newTupDesc->attrs[attn]->attname)),
+									NameStr(attr->attname)),
 							 errtablecol(oldrel, attn + 1)));
+				}
 			}
 
 			foreach(l, tab->constraints)
@@ -4927,7 +4935,7 @@ find_composite_type_dependencies(Oid typeOid, Relation origRelation,
 			continue;
 
 		rel = relation_open(pg_depend->objid, AccessShareLock);
-		att = rel->rd_att->attrs[pg_depend->objsubid - 1];
+		att = TupleDescAttr(rel->rd_att, pg_depend->objsubid - 1);
 
 		if (rel->rd_rel->relkind == RELKIND_RELATION ||
 			rel->rd_rel->relkind == RELKIND_MATVIEW ||
@@ -5693,7 +5701,7 @@ ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode)
 		AttrNumber	parent_attnum;
 
 		parent_attnum = get_attnum(parentId, colName);
-		if (tupDesc->attrs[parent_attnum - 1]->attnotnull)
+		if (TupleDescAttr(tupDesc, parent_attnum - 1)->attnotnull)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
 					 errmsg("column \"%s\" is marked NOT NULL in parent table",
@@ -7286,13 +7294,15 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
 			CoercionPathType new_pathtype;
 			Oid			old_castfunc;
 			Oid			new_castfunc;
+			Form_pg_attribute attr = TupleDescAttr(tab->oldDesc,
+												   fkattnum[i] - 1);
 
 			/*
 			 * Identify coercion pathways from each of the old and new FK-side
 			 * column types to the right (foreign) operand type of the pfeqop.
 			 * We may assume that pg_constraint.conkey is not changing.
 			 */
-			old_fktype = tab->oldDesc->attrs[fkattnum[i] - 1]->atttypid;
+			old_fktype = attr->atttypid;
 			new_fktype = fktype;
 			old_pathtype = findFkeyCast(pfeqop_right, old_fktype,
 										&old_castfunc);
@@ -8963,7 +8973,8 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 	ColumnDef  *def = (ColumnDef *) cmd->def;
 	TypeName   *typeName = def->typeName;
 	HeapTuple	heapTup;
-	Form_pg_attribute attTup;
+	Form_pg_attribute attTup,
+				attOldTup;
 	AttrNumber	attnum;
 	HeapTuple	typeTuple;
 	Form_pg_type tform;
@@ -8989,10 +9000,11 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 						colName, RelationGetRelationName(rel))));
 	attTup = (Form_pg_attribute) GETSTRUCT(heapTup);
 	attnum = attTup->attnum;
+	attOldTup = TupleDescAttr(tab->oldDesc, attnum - 1);
 
 	/* Check for multiple ALTER TYPE on same column --- can't cope */
-	if (attTup->atttypid != tab->oldDesc->attrs[attnum - 1]->atttypid ||
-		attTup->atttypmod != tab->oldDesc->attrs[attnum - 1]->atttypmod)
+	if (attTup->atttypid != attOldTup->atttypid ||
+		attTup->atttypmod != attOldTup->atttypmod)
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot alter type of column \"%s\" twice",
@@ -11209,7 +11221,8 @@ MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 
 	for (parent_attno = 1; parent_attno <= parent_natts; parent_attno++)
 	{
-		Form_pg_attribute attribute = tupleDesc->attrs[parent_attno - 1];
+		Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
+													parent_attno - 1);
 		char	   *attributeName = NameStr(attribute->attname);
 
 		/* Ignore dropped columns in the parent. */
@@ -11822,7 +11835,7 @@ ATExecAddOf(Relation rel, const TypeName *ofTypename, LOCKMODE lockmode)
 				   *table_attname;
 
 		/* Get the next non-dropped type attribute. */
-		type_attr = typeTupleDesc->attrs[type_attno - 1];
+		type_attr = TupleDescAttr(typeTupleDesc, type_attno - 1);
 		if (type_attr->attisdropped)
 			continue;
 		type_attname = NameStr(type_attr->attname);
@@ -11835,7 +11848,8 @@ ATExecAddOf(Relation rel, const TypeName *ofTypename, LOCKMODE lockmode)
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
 						 errmsg("table is missing column \"%s\"",
 								type_attname)));
-			table_attr = tableTupleDesc->attrs[table_attno++ - 1];
+			table_attr = TupleDescAttr(tableTupleDesc, table_attno - 1);
+			table_attno++;
 		} while (table_attr->attisdropped);
 		table_attname = NameStr(table_attr->attname);
 
@@ -11860,7 +11874,8 @@ ATExecAddOf(Relation rel, const TypeName *ofTypename, LOCKMODE lockmode)
 	/* Any remaining columns at the end of the table had better be dropped. */
 	for (; table_attno <= tableTupleDesc->natts; table_attno++)
 	{
-		Form_pg_attribute table_attr = tableTupleDesc->attrs[table_attno - 1];
+		Form_pg_attribute table_attr = TupleDescAttr(tableTupleDesc,
+													 table_attno - 1);
 
 		if (!table_attr->attisdropped)
 			ereport(ERROR,
@@ -12147,7 +12162,7 @@ ATExecReplicaIdentity(Relation rel, ReplicaIdentityStmt *stmt, LOCKMODE lockmode
 					 errmsg("index \"%s\" cannot be used as replica identity because column %d is a system column",
 							RelationGetRelationName(indexRel), attno)));
 
-		attr = rel->rd_att->attrs[attno - 1];
+		attr = TupleDescAttr(rel->rd_att, attno - 1);
 		if (!attr->attnotnull)
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
@@ -13451,7 +13466,7 @@ PartConstraintImpliedByRelConstraint(Relation scanrel,
 
 		for (i = 1; i <= natts; i++)
 		{
-			Form_pg_attribute att = scanrel->rd_att->attrs[i - 1];
+			Form_pg_attribute att = TupleDescAttr(scanrel->rd_att, i - 1);
 
 			if (att->attnotnull && !att->attisdropped)
 			{
@@ -13733,7 +13748,7 @@ ATExecAttachPartition(List **wqueue, Relation rel, PartitionCmd *cmd)
 	natts = tupleDesc->natts;
 	for (attno = 1; attno <= natts; attno++)
 	{
-		Form_pg_attribute attribute = tupleDesc->attrs[attno - 1];
+		Form_pg_attribute attribute = TupleDescAttr(tupleDesc, attno - 1);
 		char	   *attributeName = NameStr(attribute->attname);
 
 		/* Ignore dropped */
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c
index 29ac5d569d7..7ed16aeff46 100644
--- a/src/backend/commands/typecmds.c
+++ b/src/backend/commands/typecmds.c
@@ -2324,6 +2324,7 @@ AlterDomainNotNull(List *names, bool notNull)
 				for (i = 0; i < rtc->natts; i++)
 				{
 					int			attnum = rtc->atts[i];
+					Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
 
 					if (heap_attisnull(tuple, attnum))
 					{
@@ -2338,7 +2339,7 @@ AlterDomainNotNull(List *names, bool notNull)
 						ereport(ERROR,
 								(errcode(ERRCODE_NOT_NULL_VIOLATION),
 								 errmsg("column \"%s\" of table \"%s\" contains null values",
-										NameStr(tupdesc->attrs[attnum - 1]->attname),
+										NameStr(attr->attname),
 										RelationGetRelationName(testrel)),
 								 errtablecol(testrel, attnum)));
 					}
@@ -2722,6 +2723,7 @@ validateDomainConstraint(Oid domainoid, char *ccbin)
 				Datum		d;
 				bool		isNull;
 				Datum		conResult;
+				Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
 
 				d = heap_getattr(tuple, attnum, tupdesc, &isNull);
 
@@ -2745,7 +2747,7 @@ validateDomainConstraint(Oid domainoid, char *ccbin)
 					ereport(ERROR,
 							(errcode(ERRCODE_CHECK_VIOLATION),
 							 errmsg("column \"%s\" of table \"%s\" contains values that violate the new constraint",
-									NameStr(tupdesc->attrs[attnum - 1]->attname),
+									NameStr(attr->attname),
 									RelationGetRelationName(testrel)),
 							 errtablecol(testrel, attnum)));
 				}
@@ -2930,7 +2932,7 @@ get_rels_with_domain(Oid domainOid, LOCKMODE lockmode)
 		 */
 		if (pg_depend->objsubid > RelationGetNumberOfAttributes(rtc->rel))
 			continue;
-		pg_att = rtc->rel->rd_att->attrs[pg_depend->objsubid - 1];
+		pg_att = TupleDescAttr(rtc->rel->rd_att, pg_depend->objsubid - 1);
 		if (pg_att->attisdropped || pg_att->atttypid != domainOid)
 			continue;
 
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index f25a5658d68..076e2a3a402 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -283,8 +283,8 @@ checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc)
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
-		Form_pg_attribute newattr = newdesc->attrs[i];
-		Form_pg_attribute oldattr = olddesc->attrs[i];
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)