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Type:
Improvement
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Resolution: Duplicate
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Priority:
Major - P3
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None
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Affects Version/s: None
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Component/s: Catalog
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Labels:None
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Storage Execution
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(); rst.initiate(); const db = rst.getPrimary().getDB("test"); assert.commandWorked(db.mycoll.insert(Array.from({length: 5}, (_, i) => ({_id: i})))); const cursor = db.mycoll.find().readConcern("snapshot").batchSize(1); assert.eq({_id: 0}, cursor.next()); assert.eq({_id: 1}, cursor.next()); assert.commandWorked(db.mycoll.createIndex({a: 1})); // HERE: The getMore command fails with SnapshotUnavailable due to the collection's minimum visible // snapshot being bumped from creating the {a: 1} index. assert.eq({_id: 2}, cursor.next()); rst.stopSet();
- duplicates
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- Closed
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- related to
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- Closed
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