Fix Bug#56340 innodb updates index stats too frequently after non-index updates

This is a simple optimization issue. All stats are related to only indexed
columns, index size or number of rows in the whole table. UPDATEs that touch
only non-indexed columns cannot affect stats and we can avoid calling the
function row_update_statistics_if_needed() which may result in unnecessary I/O.

Approved by:	Marko (rb://466)

storage/innobase/row/row0mysql.c

@@ -1447,7 +1447,12 @@ run_again:
 		srv_n_rows_updated++;
 	}
 
-	row_update_statistics_if_needed(prebuilt->table);
+	/* We update table statistics only if it is a DELETE or UPDATE
+	that changes indexed columns, UPDATEs that change only non-indexed
+	columns would not affect statistics. */
+	if (node->is_delete || !(node->cmpl_info & UPD_NODE_NO_ORD_CHANGE)) {
+		row_update_statistics_if_needed(prebuilt->table);
+	}
 
 	trx->op_info = "";
 

storage/innodb_plugin/row/row0mysql.c

@@ -1422,7 +1422,12 @@ run_again:
 		srv_n_rows_updated++;
 	}
 
-	row_update_statistics_if_needed(prebuilt->table);
+	/* We update table statistics only if it is a DELETE or UPDATE
+	that changes indexed columns, UPDATEs that change only non-indexed
+	columns would not affect statistics. */
+	if (node->is_delete || !(node->cmpl_info & UPD_NODE_NO_ORD_CHANGE)) {
+		row_update_statistics_if_needed(prebuilt->table);
+	}
 
 	trx->op_info = "";