Details
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Improvement
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Resolution: Fixed
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Major - P3
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None
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None
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Fully Compatible
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QE 2021-10-04, QE 2021-10-18, QE 2021-11-01
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120
Description
We want to improve the reservation of the maximum size versus when we should reserve something smaller for the getMore command. Here's a pragmatic approach:
- For a normal cursor with no explicit batch size, 16MB.
- For a normal cursor with explicit batch size, perhaps 8MB.
- For a tailable cursor, which may often return 0 or a small number of results, perhaps 4MB.
We can better fine-tune the above heuristics based on the performance benchmarks in PERF-2565 and PERF-2566. Another worthwhile question that's worth answering as part of this task and its related experiments is that "What happens if we do not do pre-allocation at all"?
Attachments
Issue Links
- depends on
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SERVER-55535 Performance tests to exercise change streams optimizations
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- Closed
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- is depended on by
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SERVER-36346 Large memory consumption per pending getmore
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- Closed
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