diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 22bcf171ff..1f76939baa 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -214,6 +214,7 @@ static const Size max_changes_in_memory = 4096; /* XXX for restore only */
 
 /* GUC variable */
 int			debug_logical_replication_streaming = DEBUG_LOGICAL_REP_STREAMING_BUFFERED;
+int			rb_mem_block_size = 8192 * 1024L;
 
 /* ---------------------------------------
  * primary reorderbuffer support routines
@@ -341,11 +342,12 @@ ReorderBufferAllocate(void)
 	 * growing code.  These values should likely be benchmarked and set to
 	 * more suitable values.
 	 */
+	elog(LOG, "RB MEM BLOCK SIZE %ld", rb_mem_block_size * 1024L);
 	buffer->tup_context = GenerationContextCreate(new_ctx,
 												  "Tuples",
-												  SLAB_LARGE_BLOCK_SIZE,
-												  SLAB_LARGE_BLOCK_SIZE,
-												  SLAB_LARGE_BLOCK_SIZE);
+												  rb_mem_block_size * 1024L,
+												  rb_mem_block_size * 1024L,
+												  rb_mem_block_size * 1024L);
 
 	hash_ctl.keysize = sizeof(TransactionId);
 	hash_ctl.entrysize = sizeof(ReorderBufferTXNByIdEnt);
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 686309db58..7e2e492521 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -2085,6 +2085,16 @@ struct config_bool ConfigureNamesBool[] =
 
 struct config_int ConfigureNamesInt[] =
 {
+	{
+		{"rb_mem_block_size", PGC_USERSET, RESOURCES_MEM,
+		 gettext_noop(""),
+		 NULL,
+		 GUC_UNIT_KB
+		},
+		&rb_mem_block_size,
+		8192 * 1024L, 0, MAX_KILOBYTES,
+		NULL, NULL, NULL
+	},
 	{
 		{"archive_timeout", PGC_SIGHUP, WAL_ARCHIVING,
 			gettext_noop("Sets the amount of time to wait before forcing a "
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index e332635f70..37bc37236a 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -26,6 +26,7 @@
 /* GUC variables */
 extern PGDLLIMPORT int logical_decoding_work_mem;
 extern PGDLLIMPORT int debug_logical_replication_streaming;
+extern PGDLLIMPORT int rb_mem_block_size;
 
 /* possible values for debug_logical_replication_streaming */
 typedef enum