Merge mysql-5.1 to mysql-5.5.

storage/innobase/btr/btr0pcur.c

@@ -348,10 +348,10 @@ btr_pcur_restore_position_func(
 	/* Restore the old search mode */
 	cursor->search_mode = old_mode;
 
-	if (btr_pcur_is_on_user_rec(cursor)) {
 	switch (cursor->rel_pos) {
 	case BTR_PCUR_ON:
-			if (!cmp_dtuple_rec(
+		if (btr_pcur_is_on_user_rec(cursor)
+		    && !cmp_dtuple_rec(
 			    tuple, btr_pcur_get_rec(cursor),
 			    rec_get_offsets(btr_pcur_get_rec(cursor),
 					    index, NULL,
@@ -373,20 +373,15 @@ btr_pcur_restore_position_func(
 
 			return(TRUE);
 		}
-
-			break;
+#ifdef UNIV_DEBUG
+		/* fall through */
 	case BTR_PCUR_BEFORE:
-			page_cur_move_to_next(btr_pcur_get_page_cur(cursor));
-			break;
 	case BTR_PCUR_AFTER:
-			page_cur_move_to_prev(btr_pcur_get_page_cur(cursor));
 		break;
-#ifdef UNIV_DEBUG
 	default:
 		ut_error;
 #endif /* UNIV_DEBUG */
 	}
-	}
 
 	mem_heap_free(heap);
 

storage/innobase/row/row0merge.c

@@ -1235,11 +1235,25 @@ row_merge_read_clustered_index(
 				goto err_exit;
 			}
 
+			/* Store the cursor position on the last user
+			record on the page. */
+			btr_pcur_move_to_prev_on_page(&pcur);
+			/* Leaf pages must never be empty, unless
+			this is the only page in the index tree. */
+			ut_ad(btr_pcur_is_on_user_rec(&pcur)
+			      || buf_block_get_page_no(
+				      btr_pcur_get_block(&pcur))
+			      == clust_index->page);
+
 			btr_pcur_store_position(&pcur, &mtr);
 			mtr_commit(&mtr);
 			mtr_start(&mtr);
+			/* Restore position on the record, or its
+			predecessor if the record was purged
+			meanwhile. */
 			btr_pcur_restore_position(BTR_SEARCH_LEAF,
 						  &pcur, &mtr);
+			/* Move to the successor of the original record. */
 			has_next = btr_pcur_move_to_next_user_rec(&pcur, &mtr);
 		}