[DOCS-13668] Investigate changes in SERVER-40755: Expose statistics which indicate how many collection scans have executed Created: 26/May/20  Updated: 13/Nov/23  Resolved: 05/Jun/20

Status: Closed
Project: Documentation
Component/s: manual, Server
Affects Version/s: None
Fix Version/s: 4.3.1, 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: John Williams
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Documented
documents SERVER-40755 Expose statistics which indicate how ... Closed
Participants:
Days since reply: 3 years, 35 weeks, 5 days ago
Epic Link: DOCS: 4.4 Server Release Work

 Description   

Description

Downstream Change Summary

The number of tailable and non-tailable collection scans are now reported in the metrics.queryExecutor.collectionScans section of serverStatus output:

MongoDB Enterprise > db.serverStatus().metrics.queryExecutor.collectionScans
{ "nonTailable" : NumberLong(0), "total" : NumberLong(0) }

These stats can also be retrieved on a per-collection basis using the queryExecStats option to the $collStats aggregation stage:

MongoDB Enterprise > db.c.aggregate([{$collStats: {queryExecStats: {}}}])
{ "ns" : "test.c", "host" : "storchbox:27017", "localTime" : ISODate("2020-05-26T19:44:04.850Z"), "queryExecStats" : { "collectionScans" : { "total" : NumberLong(0), "nonTailable" : NumberLong(0) } } }

Description of Linked Ticket

It is unclear how prevalent are data scans. Having statistics on collection and index scans would allow us to decided if improvements in this area are critical for the overall performance.

Scope of changes

Impact to Other Docs

MVP (Work and Date)

Resources (Scope or Design Docs, Invision, etc.)



 Comments   
Comment by Githook User [ 05/Jun/20 ]

Author:

{'name': 'John Williams', 'email': 'john.williams@10gen.com', 'username': 'jwilliams-mongo'}

Message: DOCS-13668: Expose statistics which indicate how many collection scans have executed
Branch: master
https://github.com/mongodb/docs/commit/4e3eca3ce56b13e6119e3ecf4532383b1586a76e

Comment by John Williams [ 05/Jun/20 ]

https://github.com/mongodb/docs/pull/4134

Comment by John Williams [ 03/Jun/20 ]

cr: https://mongodbcr.appspot.com/620290081/

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