-/* Copyright (c) 2009, 2010 Nicira Networks.
+/* Copyright (c) 2009, 2010, 2011 Nicira Networks.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
idl->monitor_request_id = NULL;
ovsdb_idl_clear(idl);
ovsdb_idl_parse_update(idl, msg->result);
- } else if (msg->type == JSONRPC_REPLY
- && msg->id && msg->id->type == JSON_STRING
+ } else if (msg->type == JSONRPC_REPLY && msg->id->type == JSON_STRING
&& !strcmp(msg->id->u.string, "echo")) {
/* It's a reply to our echo request. Ignore it. */
} else if ((msg->type == JSONRPC_ERROR
&class->columns[idx];
if (row->old
- ? !ovsdb_datum_equals(&row->old[idx], &row->new[idx],
- &column->type)
- : !ovsdb_datum_is_default(&row->new[idx],
+ || !ovsdb_datum_is_default(&row->new[idx],
&column->type)) {
json_object_put(row_json, column->name,
substitute_uuids(
assert(row->old == NULL ||
row->table->modes[column_idx] & OVSDB_IDL_MONITOR);
+ /* If this is a write-only column and the datum being written is the same
+ * as the one already there, just skip the update entirely. This is worth
+ * optimizing because we have a lot of columns that get periodically
+ * refreshed into the database but don't actually change that often.
+ *
+ * We don't do this for read/write columns because that would break
+ * atomicity of transactions--some other client might have written a
+ * different value in that column since we read it. */
+ if (row->table->modes[column_idx] == OVSDB_IDL_MONITOR
+ && ovsdb_datum_equals(ovsdb_idl_read(row, column),
+ datum, &column->type)) {
+ ovsdb_datum_destroy(datum, &column->type);
+ return;
+ }
+
if (hmap_node_is_null(&row->txn_node)) {
hmap_insert(&row->table->idl->txn->txn_rows, &row->txn_node,
uuid_hash(&row->uuid));