SERVER-47726 Log delta-style oplog entries from pipeline based updates

1 files changed, 63 insertions, 0 deletions

diff --git a/src/mongo/db/update/update_oplog_entry_version.h b/src/mongo/db/update/update_oplog_entry_version.h
new file mode 100644
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+++ b/src/mongo/db/update/update_oplog_entry_version.h
@@ -0,0 +1,63 @@
+/**
+ *    Copyright (C) 2018-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include "mongo/base/string_data.h"
+
+namespace mongo {
+
+static inline constexpr StringData kUpdateOplogEntryVersionFieldName = "$v"_sd;
+
+/**
+ * There are multiple types of 'u' (update) oplog entries. The type of an entry is indicated using
+ * a field called $v.
+ *
+ * The values in this enum *MUST* not change unless we remove support for a type of update.
+ */
+enum class UpdateOplogEntryVersion {
+    // Ancient update system which was deleted in 4.0. We still reserve its version number.
+    kRemovedV0 = 0,
+
+    // The update system introduced in v3.6. When a single update adds multiple fields, those
+    // fields are added in lexicographic order by field name. This system introduces support for
+    // arrayFilters and $[] syntax.
+    kUpdateNodeV1 = 1,
+
+    // Delta style update, introduced in 4.6. When a pipeline based update is executed, the pre and
+    // post images are diffed, producing a delta. The delta is recorded in the oplog. On
+    // secondaries, the delta is applied to the pre-image to recover the post image.
+    //
+    // Delta style updates cannot be executed directly by users.
+    kDeltaV2 = 2,
+
+    // Must be last.
+    kNumVersions
+};
+}  // namespace mongo