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| author | Daniel Gottlieb <daniel.gottlieb@mongodb.com> | 2019-01-24 20:35:57 -0500 |
|---|---|---|
| committer | Daniel Gottlieb <daniel.gottlieb@mongodb.com> | 2019-01-24 20:35:57 -0500 |
| commit | 5f213f2d419d9549559281fef7d3704ad7614d12 (patch) | |
| tree | 6c37c0f4c12d53fcfd0faefa63807de46a280f05 /src/mongo/db/storage/SConscript | |
| parent | 3a1b11c960c6fc9bc5c94e4d5cd58f38c78ca55b (diff) | |
| download | mongo-5f213f2d419d9549559281fef7d3704ad7614d12.tar.gz | |
SERVER-38499: Enforce oplog visibility at the MongoDB layer.
WiredTiger guards against transactions preparing with a timestamp
earlier than the most recent reader. This guarantees no reader may
have seen the wrong version of a document.
The oplog is a special case. Because the oplog does not contain
prepared updates, and oplog readers cannot read from other
collections, it's valid to prepare behind an oplog readers
timestamp.
However, WiredTiger is not aware the oplog is special. When MongoDB
uses WiredTiger `read_timestamp`s to enforce oplog visibility, there
are cases (specifically, secondary oplog application) where an oplog
reader can be in front of an impending prepare.
There were two strategies available for resolving this. The first is
to artificially hold back what oplog is available to read at until
nothing can be prepared behind an oplog reader. The second strategy,
which is what this patch does, is to have the MongoDB layer hide
documents that are newer than the visibility point. The mechanism for
calculating and discovering the visibility point is unchanged.
Diffstat (limited to 'src/mongo/db/storage/SConscript')
| -rw-r--r-- | src/mongo/db/storage/SConscript | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/src/mongo/db/storage/SConscript b/src/mongo/db/storage/SConscript index e82a86d5cdb..4d3f4bec2af 100644 --- a/src/mongo/db/storage/SConscript +++ b/src/mongo/db/storage/SConscript @@ -251,6 +251,7 @@ env.Library( LIBDEPS_PRIVATE=[ "$BUILD_DIR/mongo/base", "$BUILD_DIR/mongo/db/storage/storage_options", + '$BUILD_DIR/mongo/util/fail_point', ], ) |