From ba0c2f4045a58c2d11e12d5f0e5d770765be6c82 Mon Sep 17 00:00:00 2001
From: David Rowley <dgrowley@gmail.com>
Date: Wed, 24 Apr 2024 14:14:44 +1200
Subject: [PATCH v2] Ensure we allocate NAMEDATALEN bytes for names in Index
 Only Scans

---
 src/backend/executor/nodeIndexonlyscan.c | 55 ++++++++++++++++++++++--
 src/include/nodes/execnodes.h            |  4 ++
 2 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c
index fcf6d1d932..93ab69ba50 100644
--- a/src/backend/executor/nodeIndexonlyscan.c
+++ b/src/backend/executor/nodeIndexonlyscan.c
@@ -45,8 +45,8 @@
 
 
 static TupleTableSlot *IndexOnlyNext(IndexOnlyScanState *node);
-static void StoreIndexTuple(TupleTableSlot *slot, IndexTuple itup,
-							TupleDesc itupdesc);
+static void StoreIndexTuple(IndexOnlyScanState *node, TupleTableSlot *slot,
+							IndexTuple itup, TupleDesc itupdesc);
 
 
 /* ----------------------------------------------------------------
@@ -205,7 +205,7 @@ IndexOnlyNext(IndexOnlyScanState *node)
 			ExecForceStoreHeapTuple(scandesc->xs_hitup, slot, false);
 		}
 		else if (scandesc->xs_itup)
-			StoreIndexTuple(slot, scandesc->xs_itup, scandesc->xs_itupdesc);
+			StoreIndexTuple(node, slot, scandesc->xs_itup, scandesc->xs_itupdesc);
 		else
 			elog(ERROR, "no data returned for index-only scan");
 
@@ -263,7 +263,8 @@ IndexOnlyNext(IndexOnlyScanState *node)
  * right now we don't need it elsewhere.
  */
 static void
-StoreIndexTuple(TupleTableSlot *slot, IndexTuple itup, TupleDesc itupdesc)
+StoreIndexTuple(IndexOnlyScanState *node, TupleTableSlot *slot,
+				IndexTuple itup, TupleDesc itupdesc)
 {
 	/*
 	 * Note: we must use the tupdesc supplied by the AM in index_deform_tuple,
@@ -276,6 +277,26 @@ StoreIndexTuple(TupleTableSlot *slot, IndexTuple itup, TupleDesc itupdesc)
 
 	ExecClearTuple(slot);
 	index_deform_tuple(itup, itupdesc, slot->tts_values, slot->tts_isnull);
+
+	if (node->ioss_ConvertDatumIdxs != NULL)
+	{
+		for (int i = 0; i < node->ioss_ConvertDatumCount; i++)
+		{
+			int		j = node->ioss_ConvertDatumIdxs[i];
+			Name	name;
+
+			/* skip null Datums */
+			if (slot->tts_isnull[j])
+				continue;
+
+			name = (Name) MemoryContextAlloc(node->ss.ps.ps_ExprContext->ecxt_per_tuple_memory,
+											 NAMEDATALEN);
+
+			namestrcpy(name, DatumGetCString(slot->tts_values[j]));
+			slot->tts_values[j] = NameGetDatum(name);
+		}
+	}
+
 	ExecStoreVirtualTuple(slot);
 }
 
@@ -603,6 +624,32 @@ ExecInitIndexOnlyScan(IndexOnlyScan *node, EState *estate, int eflags)
 		indexstate->ioss_RuntimeContext = NULL;
 	}
 
+	indexstate->ioss_ConvertDatumIdxs = NULL;
+	indexstate->ioss_ConvertDatumCount = 0;
+
+	{
+		int		name_count = 0;
+		for (int i = 0; i < tupDesc->natts; i++)
+		{
+			if (tupDesc->attrs[i].atttypid == NAMEOID)
+				name_count++;
+		}
+
+		if (name_count > 0)
+		{
+			int j = 0;
+			indexstate->ioss_ConvertDatumIdxs = palloc(sizeof(int) * name_count);
+
+			for (int i = 0; i < tupDesc->natts; i++)
+			{
+				if (tupDesc->attrs[i].atttypid == NAMEOID)
+					indexstate->ioss_ConvertDatumIdxs[j++] = i;
+			}
+		}
+
+		indexstate->ioss_ConvertDatumCount = name_count;
+	}
+
 	/*
 	 * all done.
 	 */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index d927ac44a8..6d72e04fe7 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1690,6 +1690,8 @@ typedef struct IndexScanState
  *		TableSlot		   slot for holding tuples fetched from the table
  *		VMBuffer		   buffer in use for visibility map testing, if any
  *		PscanLen		   size of parallel index-only scan descriptor
+ *		ConvertDatumIdxs   Index of Datums from the index to convert to heap type
+ *		ConvertDatumCount  Number of elements in ConvertDatumIdxs
  * ----------------
  */
 typedef struct IndexOnlyScanState
@@ -1709,6 +1711,8 @@ typedef struct IndexOnlyScanState
 	TupleTableSlot *ioss_TableSlot;
 	Buffer		ioss_VMBuffer;
 	Size		ioss_PscanLen;
+	int		   *ioss_ConvertDatumIdxs;
+	int			ioss_ConvertDatumCount;
 } IndexOnlyScanState;
 
 /* ----------------
-- 
2.40.1.windows.1