[SERVER-81103] disable mirroredReads in plan_cache_stats_all_hosts_sharded Created: 15/Sep/23 Updated: 29/Oct/23 Resolved: 15/Sep/23 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | None |
| Affects Version/s: | None |
| Fix Version/s: | 7.1.0-rc4 |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Maddie Zechar | Assignee: | Maddie Zechar |
| Resolution: | Fixed | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Backwards Compatibility: | Fully Compatible | ||||||||
| Operating System: | ALL | ||||||||
| Backport Requested: |
v7.1
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| Sprint: | QI 2023-09-18 | ||||||||
| Participants: | |||||||||
| Linked BF Score: | 8 | ||||||||
| Description |
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Starting in 4.4, mirrored reads are enabled by default with a sampling rate of 0.10. If not disabled, the primary node mirrors supported reads (this includes find queries) to the secondary node's cache to "warm it up" to reduce performance impact of primary elections. Here the cache means "everything on RAM", which includes the plan cache. Thus even though the primary node executes a find query, the secondary's cache will "mirror" this read and have a plan for it in its plan cache. This results in the secondary having more plans in the cache than it executed. We disable this mirroring so the test passes in burn_in_tests. |
| Comments |
| Comment by Githook User [ 21/Sep/23 ] |
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Author: {'name': 'madelinezec', 'email': 'mez2113@columbia.edu', 'username': 'madelinezec'}Message: |
| Comment by Maria Prinus [ 20/Sep/23 ] |
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Hi maddie.zechar@mongodb.com, there is a request for 7.1 backport, please, note that v7.1 is frozen. Reach out to @server-release-managers in #server-release channel to merge the backport to 7.1 |
| Comment by Liubov Molchanova [ 20/Sep/23 ] |
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Requesting backport as the issue continues to happen on v7.1 (please, see BFG-2094095) |
| Comment by Githook User [ 15/Sep/23 ] |
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Author: {'name': 'madelinezec', 'email': 'mez2113@columbia.edu', 'username': 'madelinezec'}Message: |