[DOCS-14453] Investigate changes in SERVER-53762: Report aggregate execution stats in explain for the inner side of $lookup Created: 13/May/21 Updated: 13/Nov/23 Resolved: 23/Aug/21 |
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| Status: | Closed |
| Project: | Documentation |
| Component/s: | manual, Server |
| Affects Version/s: | None |
| Fix Version/s: | 5.0.0-rc0, Server_Docs_20231030, Server_Docs_20231106, Server_Docs_20231105, Server_Docs_20231113 |
| Type: | Task | Priority: | Major - P3 |
| Reporter: | Backlog - Core Eng Program Management Team | Assignee: | Jason Price |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Participants: | |||||||||
| Days since reply: | 2 years, 24 weeks, 2 days ago | ||||||||
| Epic Link: | DOCSP-15042 | ||||||||
| Story Points: | 3 | ||||||||
| Description |
DescriptionDownstream Change Summary In this ticket, we've modified the explain output for aggregations using $lookup. If the explain verbosity is allPlansExecution or above, we will add total aggregate execution stats to the output. (The specific stats are totalDocsExamined, totalKeysExamined, collectionScans (the number as an integer), and indexesUsed (an array of the index names). Description of Linked TicketAs part of Now that we are tracking these values, it would be valuable for debugging/diagnostics to expose them in "executionStats" or "allPlansExecution" level explain output. We will need to choose which metrics are exposed, but I think it would at the very least include docs examined and keys examined. This would be especially helpful in understanding the performance properties of the subpipeline, since explain currently does not display the execution plan used on the inner side (see SERVER-22622). Any information in explain as to whether the $lookup subpipeline is cheap or expensive and why would be immensely helpful for query performance debugging scenarios. Scope of changesConsider if we need to update the $lookup docs as part of this change. Impact to Other DocsMVP (Work and Date)Resources (Scope or Design Docs, Invision, etc.) |
| Comments |
| Comment by Githook User [ 23/Aug/21 ] |
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Author: {'name': 'jason-price-mongodb', 'email': 'jshfjghsdfgjsdjh@aolsdjfhkjsdhfkjsdf.com'}Message:
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