[SERVER-42598] Periodic slow queries Created: 02/Aug/19 Updated: 05/Aug/19 Resolved: 05/Aug/19 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Performance, WiredTiger |
| Affects Version/s: | 4.0.9 |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | David Liao | Assignee: | Danny Hatcher (Inactive) |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Environment: |
Ubuntu 16.04 LTS, AWS i3.16xl |
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| Attachments: |
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| Operating System: | ALL |
| Steps To Reproduce: | Happens very regularly |
| Participants: |
| Description |
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Hi, we're seeing periodic slow queries in our mongo logs for queries on _id and is indexed. We recently made lots of effort on trimming down our database size as well as index size and synced a new replica set so compaction happened, our indexes now should fit in memory but we are still seeing poor performance on basic queries. Attached you can find our diagnostics data |
| Comments |
| Comment by Danny Hatcher (Inactive) [ 05/Aug/19 ] |
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From a quick look at the diagnostics, I can see that you still have some un-optimized queries. At points in time, the ratio of index keys vs documents scanned reaches 79,101.667/s : 812,876.167/s. The ideal ratio is 1:1. The SERVER project is for bugs and feature requests and this looks like a query optimization issue. As such, I encourage you to ask our community for further help by posting on the mongodb-user group or on Stack Overflow with the mongodb tag. |