[SERVER-82079] Count clustered index scan as indexScan and not collectionScan in $lookup explain output Created: 11/Oct/23 Updated: 14/Nov/23 |
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| Status: | Backlog |
| Project: | Core Server |
| Component/s: | None |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Tarun Gaur (Inactive) | Assignee: | Backlog - Query Execution |
| Resolution: | Unresolved | Votes: | 1 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Assigned Teams: |
Query Execution
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| Operating System: | ALL |
| Participants: |
| Description |
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Based on this community post: https://www.mongodb.com/community/forums/t/clustered-collections-as-lookup-target/246893 The user is worried we are not using clustered index, because in explain output for $lookup they see a lot of collectionScans and no indexes used. It happens because internally clustered index scan is a collection scan and not an index scan. We should improve explain output by showing explicitly that clustered index is used. |