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authorDianna Hohensee <dianna.hohensee@mongodb.com>2020-06-17 12:00:20 -0400
committerEvergreen Agent <no-reply@evergreen.mongodb.com>2020-06-17 16:13:38 +0000
commit59235bae1cbfa1ebdd2b2a12857e4f160a9afe70 (patch)
treeb57d80f04d41eeb889a9c1eab0f20a66cc07b623
parent548c78a2d94006152a4ff52a750222a402166a18 (diff)
downloadmongo-59235bae1cbfa1ebdd2b2a12857e4f160a9afe70.tar.gz
SERVER-47296 Execution Architecture Guide: Oplog Collection, fix incomplete commit
-rw-r--r--src/mongo/db/catalog/README.md18
1 files changed, 7 insertions, 11 deletions
diff --git a/src/mongo/db/catalog/README.md b/src/mongo/db/catalog/README.md
index 811ea7e5e44..7fa675c60a2 100644
--- a/src/mongo/db/catalog/README.md
+++ b/src/mongo/db/catalog/README.md
@@ -553,8 +553,6 @@ _Code spelunking starting points:_
* 'durable' confusingly means journaling is enabled.
* [_Whether WT journals a collection_](https://github.com/mongodb/mongo/blob/r4.5.0/src/mongo/db/storage/wiredtiger/wiredtiger_util.cpp#L560-L580)
-What collections are journaled, and how.
-
# Flow Control
What it does (motivation). How does it do it? Ticketing.
@@ -782,24 +780,22 @@ Additionally, secondaries apply batches of oplog entries out of order and simila
unclean shutdown.
# Glossary
-_put terms here that can either be briefly explained in order to be simply referenced by above sections; or terms with links to sections for complete explanation so topics can be found quickly when not obviously covered by a section_
-
-**ident**: An ident is a unique identifier given to a storage engine resource. Collections and
-indexes map application-layer names to storage engine idents. In WiredTiger, idents are implemented
-as tables. For example, collection idents have the form: `collection-<counter>-<random number>`.
-
**binary comparable**: Two values are binary comparable if the lexicographical order over their byte
representation, from lower memory addresses to higher addresses, is the same as the defined ordering
for that type. For example, ASCII strings are binary comparable, but double precision floating point
numbers and little-endian integers are not.
-**`oplog hole`**: an uncommitted oplog write that can exist with out-of-order writes when a later
+**ident**: An ident is a unique identifier given to a storage engine resource. Collections and
+indexes map application-layer names to storage engine idents. In WiredTiger, idents are implemented
+as tables. For example, collection idents have the form: `collection-<counter>-<random number>`.
+
+**oplog hole**: an uncommitted oplog write that can exist with out-of-order writes when a later
timestamped write happens to commit first. Oplog holes can exist in-memory and persisted on disk.
-**`oplogReadTimestamp`**: the timestamp used for WT forward cursor oplog reads in order to avoid
+**oplogReadTimestamp**: the timestamp used for WT forward cursor oplog reads in order to avoid
advancing past oplog holes. Tracks in-memory oplog holes.
-**`oplogTruncateAfterPoint`**: the timestamp after which oplog entries will be truncated during
+**oplogTruncateAfterPoint**: the timestamp after which oplog entries will be truncated during
startup recovery after an unclean shutdown. Tracks persisted oplog holes.
[`BSONObj::woCompare`]: https://github.com/mongodb/mongo/blob/v4.4/src/mongo/bson/bsonobj.h#L460