[SERVER-30883] Fast-path caching of oldest oplog entry Created: 30/Aug/17  Updated: 30/Oct/23  Resolved: 12/Feb/20

Status: Closed
Project: Core Server
Component/s: Replication, WiredTiger
Affects Version/s: None
Fix Version/s: 4.3.4

Type: Improvement Priority: Major - P3
Reporter: Bernard Gorman Assignee: Eric Milkie
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Problem/Incident
causes SERVER-47179 Requesting 'oplog' serverStatus secti... Closed
Related
Backwards Compatibility: Fully Compatible
Sprint: Execution Team 2020-01-13, Execution Team 2020-01-27, Execution Team 2020-02-10, Execution Team 2020-02-24
Participants:
Case:

 Description   

When the serverStatus command is invoked, its oplog section collects the most recent applied optime and retrieves the first entry from the oplog collection. Because the oldest op is less likely to be present in the WT cache, this may require us to read from disk, and possibly to wait for space during periods of high cache pressure.

Given the frequency with which serverStatus is called for FTDC collection and by the Monitoring Agent, we should consider implementing a separate caching mechanism and fast-path this query to avoid I/O and WT cache contention.



 Comments   
Comment by Githook User [ 12/Feb/20 ]

Author:

{'username': 'milkie', 'name': 'Eric Milkie', 'email': 'milkie@10gen.com'}

Message: SERVER-30883 fast-path fetching of oldest oplog entry

This reverts commit b81a373933e8481fa40f4b6fc692e537df2e307b.
Branch: master
https://github.com/mongodb/mongo/commit/e561492b2547bc8247692731f0682da499bacc8f

Comment by Githook User [ 09/Jan/20 ]

Author:

{'name': 'Eric Milkie', 'email': 'milkie@mongodb.com', 'username': 'milkie'}

Message: Revert "SERVER-30883 fast-path fetching of oldest oplog entry"

This reverts commit ece14c8410785b6d1f37a221307b1a0f1ca4e82d.
Branch: master
https://github.com/mongodb/mongo/commit/b81a373933e8481fa40f4b6fc692e537df2e307b

Comment by Githook User [ 08/Jan/20 ]

Author:

{'name': 'Eric Milkie', 'email': 'milkie@mongodb.com', 'username': 'milkie'}

Message: SERVER-30883 fast-path fetching of oldest oplog entry
Branch: master
https://github.com/mongodb/mongo/commit/ece14c8410785b6d1f37a221307b1a0f1ca4e82d

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