[DOCS-14760] Investigate changes in SERVER-53303: Make sort and group execution stages report number of spills to disk in explain Created: 25/Aug/21  Updated: 13/Nov/23  Resolved: 30/Sep/21

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: Naomi Pentrel (Inactive)
Resolution: Gone away Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Documented
documents SERVER-53303 Make sort and group execution stages ... Closed
Participants:
Days since reply: 2 years, 18 weeks, 6 days ago
Epic Link: DOCSP-15042

 Description   
Downstream Change Summary

This ticket made changes to the explain output such that the sort and group exec stages report the number of times they spill to disk. This information might be too much detail for the docs, but flagging downstream attention to the Docs team just in case.

Description of Linked Ticket

Work done under SERVER-51026 recently extended the query execution systems runtime stats to track the individual number of times that a sort stage spills to disk. However, explain currently only reports whether a SORT PlanStage used disk with a boolean; if disk was used, we don't indicate the number of times that we spilled sorted data to disk. We should take advantage of the work done in SERVER-51026 and report this "spills" metric for the SORT stage.

Additionally, it would be good to report this as a runtime stat for the $sort DocumentSource. We could also make a similar extension and report the number of spills for a $group. This could build on the work done in SERVER-48380 and SERVER-49027 to add additional runtime stats for $sort and $group to agg explain output.



 Comments   
Comment by Naomi Pentrel (Inactive) [ 30/Sep/21 ]

We do not cover execustion stats for individual stages inside the explain results, so we will not cover this.

Comment by PM Bot [ 25/Aug/21 ]

Downstream changes updated for upstream SERVER-53303:
This ticket made changes to the explain output such that the sort and group exec stages report the number of times they spill to disk. This information might be too much detail for the docs, but flagging downstream attention to the Docs team just in case.

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