Include column name in build_attrmap_by_position's error reports.

Formerly we only provided the column number, but it's frequently
more useful to mention the column name.  The input tupdesc often
doesn't have useful column names, but the output tupdesc usually
contains user-supplied names, so report that one.

Author: Marcos Pegoraro <marcos@f10.com.br>
Co-authored-by: jian he <jian.universality@gmail.com>
Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us>
Co-authored-by: Erik Wienhold <ewie@ewie.name>
Reviewed-by: Vladlen Popolitov <v.popolitov@postgrespro.ru>
Discussion: https://postgr.es/m/CAB-JLwanky28gjAMdnMh1CjyO1b2zLdr6UOA1-oY9G7PVL9KKQ@mail.gmail.com

1 files changed, 13 insertions, 15 deletions

diff --git a/src/backend/access/common/attmap.c b/src/backend/access/common/attmap.c
index 4b6cfe05c02..4901ebecef7 100644
--- a/src/backend/access/common/attmap.c
+++ b/src/backend/access/common/attmap.c
@@ -96,33 +96,31 @@ build_attrmap_by_position(TupleDesc indesc,
 	same = true;
 	for (i = 0; i < n; i++)
 	{
-		Form_pg_attribute att = TupleDescAttr(outdesc, i);
-		Oid			atttypid;
-		int32		atttypmod;
+		Form_pg_attribute outatt = TupleDescAttr(outdesc, i);
 
-		if (att->attisdropped)
+		if (outatt->attisdropped)
 			continue;			/* attrMap->attnums[i] is already 0 */
 		noutcols++;
-		atttypid = att->atttypid;
-		atttypmod = att->atttypmod;
 		for (; j < indesc->natts; j++)
 		{
-			att = TupleDescAttr(indesc, j);
-			if (att->attisdropped)
+			Form_pg_attribute inatt = TupleDescAttr(indesc, j);
+
+			if (inatt->attisdropped)
 				continue;
 			nincols++;
 
 			/* Found matching column, now check type */
-			if (atttypid != att->atttypid ||
-				(atttypmod != att->atttypmod && atttypmod >= 0))
+			if (outatt->atttypid != inatt->atttypid ||
+				(outatt->atttypmod != inatt->atttypmod && outatt->atttypmod >= 0))
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
 						 errmsg_internal("%s", _(msg)),
-						 errdetail("Returned type %s does not match expected type %s in column %d.",
-								   format_type_with_typemod(att->atttypid,
-															att->atttypmod),
-								   format_type_with_typemod(atttypid,
-															atttypmod),
+						 errdetail("Returned type %s does not match expected type %s in column \"%s\" (position %d).",
+								   format_type_with_typemod(inatt->atttypid,
+															inatt->atttypmod),
+								   format_type_with_typemod(outatt->atttypid,
+															outatt->atttypmod),
+								   NameStr(outatt->attname),
 								   noutcols)));
 			attrMap->attnums[i] = (AttrNumber) (j + 1);
 			j++;