Details
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Improvement
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Status: Closed
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Major - P3
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Resolution: Duplicate
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None
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None
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None
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Storage Execution
Description
Creating or dropping an index raises the collection's minimum visible snapshot. This causes a getMore on a snapshot cursor to return a SnapshotUnavailable error response, even if it wouldn't use that index. Longer-running snapshot reads would be more useful if their query plan wasn't impacted by the change to the collection's minimum visible snapshot.
const rst = new ReplSetTest({nodes: 1}); |
rst.startSet();
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rst.initiate();
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const db = rst.getPrimary().getDB("test"); |
assert.commandWorked(db.mycoll.insert(Array.from({length: 5}, (_, i) => ({_id: i}))));
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const cursor = db.mycoll.find().readConcern("snapshot").batchSize(1); |
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assert.eq({_id: 0}, cursor.next());
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assert.eq({_id: 1}, cursor.next());
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assert.commandWorked(db.mycoll.createIndex({a: 1}));
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// HERE: The getMore command fails with SnapshotUnavailable due to the collection's minimum visible
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// snapshot being bumped from creating the {a: 1} index.
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assert.eq({_id: 2}, cursor.next());
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rst.stopSet();
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Attachments
Issue Links
- duplicates
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- Closed
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- related to
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- Closed
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