Minor performance update

Cache Relation Key in TupleTableSlot to Optimize Tuple Decryption.
This commit cache the relation key directly in the TupleTableSlot to avoid
repeated key lookups for each tuple decryption.

src/access/pg_tde_slot.c

@@ -43,11 +43,12 @@ static inline void tdeheap_tts_buffer_heap_store_tuple(TupleTableSlot *slot,
 											   HeapTuple tuple,
 											   Buffer buffer,
 											   bool transfer_pin);
-
+static inline RelKeyData *get_current_slot_relation_key(TDEBufferHeapTupleTableSlot *bslot, Relation rel);
 static void
 tdeheap_tts_buffer_heap_init(TupleTableSlot *slot)
 {
     TDEBufferHeapTupleTableSlot *bslot = (TDEBufferHeapTupleTableSlot *) slot;
+	bslot->cached_relation_key = NULL;
 }
 
 static void
@@ -509,7 +510,7 @@ PGTdeExecStoreBufferHeapTuple(Relation rel,
 
 	if (rel->rd_rel->relkind != RELKIND_TOASTVALUE)
 	{
-		RelKeyData *key = GetRelationKey(rel->rd_locator);
+		RelKeyData *key = get_current_slot_relation_key(bslot, rel);
 		slot_copytuple(bslot->decrypted_buffer, tuple);
 		PG_TDE_DECRYPT_TUPLE_EX(tuple, (HeapTuple)bslot->decrypted_buffer, key, "ExecStoreBuffer");
 		tuple->t_data = ((HeapTuple)bslot->decrypted_buffer)->t_data;
@@ -547,7 +548,7 @@ PGTdeExecStorePinnedBufferHeapTuple(Relation rel,
 
 	if (rel->rd_rel->relkind != RELKIND_TOASTVALUE)
 	{
-		RelKeyData *key = GetRelationKey(rel->rd_locator);
+		RelKeyData *key = get_current_slot_relation_key(bslot,rel);
 
 		slot_copytuple(bslot->decrypted_buffer, tuple);
 		PG_TDE_DECRYPT_TUPLE_EX(tuple, (HeapTuple)bslot->decrypted_buffer, key, "ExecStorePinnedBuffer");
@@ -561,3 +562,12 @@ PGTdeExecStorePinnedBufferHeapTuple(Relation rel,
 
 	return slot;
 }
+
+static inline RelKeyData*
+get_current_slot_relation_key(TDEBufferHeapTupleTableSlot *bslot, Relation rel)
+{
+	Assert(bslot != NULL);
+	if (bslot->cached_relation_key == NULL)
+		bslot->cached_relation_key = GetRelationKey(rel->rd_locator);
+	return bslot->cached_relation_key;
+}

src/include/access/pg_tde_slot.h

@@ -11,9 +11,10 @@
 #define PG_TDE_SLOT_H
 
 
- #include "postgres.h"
- #include "executor/tuptable.h"
- #include "utils/relcache.h"
+#include "postgres.h"
+#include "executor/tuptable.h"
+#include "access/pg_tde_tdemap.h"
+#include "utils/relcache.h"
 
 /* heap tuple residing in a buffer */
 typedef struct TDEBufferHeapTupleTableSlot
@@ -30,6 +31,7 @@ typedef struct TDEBufferHeapTupleTableSlot
 	 */
 	Buffer		buffer;			/* tuple's buffer, or InvalidBuffer */
 	char		decrypted_buffer[BLCKSZ];
+	RelKeyData *cached_relation_key;
 } TDEBufferHeapTupleTableSlot;
 
 extern PGDLLIMPORT const TupleTableSlotOps TTSOpsTDEBufferHeapTuple;