Details
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Task
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Resolution: Done
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Major - P3
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mongodb-3.0
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None
Description
The `saveState` and `restoreState` fields in MongoDB 3.0 explain.executionStats are not currently documented:
http://docs.mongodb.org/manual/reference/explain-results/#explain.executionStats
These are counters for the number of times a query stage yielded (saveState) and then resumed (restoreState). For example, a collection scan (COLLSCAN) stage might need to yield to fetch documents that aren't in memory yet. Queries also yield so they can be interleaved with other queries and safely stopped via $maxTimeMS or kill operations.
Ref: https://github.com/mongodb/mongo/blob/v3.0/src/mongo/db/query/explain.cpp#L223