[SERVER-62988] Investigate avoiding an extra document fetch on bounded collection scans Created: 26/Jan/22 Updated: 23/Jan/24 |
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| Status: | Backlog |
| Project: | Core Server |
| Component/s: | None |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Improvement | Priority: | Major - P3 |
| Reporter: | Josef Ahmad | Assignee: | Backlog - Storage Execution Team |
| Resolution: | Unresolved | Votes: | 0 |
| Labels: | clustered_collections, time-series | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Assigned Teams: |
Storage Execution
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| Description |
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Cluster key lookups fetch an extra document, compared to index scans which only (walk the key and) only fetch the documents that match the predicate. The example below respectively fetches 2 documents to return 1 on a bounded collscan for a clustered collection, and walks 1 key to fetch 1 document and return 1 document on an index scan for a non-clustered collection.
While clustered collection queries generally outperform non-clustered collection queries as they avoid the index lookup, we should explore avoiding the extra document fetch as an additional performance improvement. |
| Comments |
| Comment by Steve Tarzia [ 15/Nov/22 ] |
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joe.sack@mongodb.com any guidance on the priority of this? |
| Comment by Ana Meza [ 10/Nov/22 ] |
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As part of the TS perf work PM-3050, the team also implemented the missing piece for PM-2556: Support clustered collections in multiplanner for all collections - So we are closing PM-2556 and sending this SERVER ticket back to the Triage queue |
| Comment by Connie Chen [ 18/Apr/22 ] |
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Passing this along to Query as there is planned work for 7.0 around clustered collections for the Query Roadmap
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| Comment by Connie Chen [ 07/Feb/22 ] |
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We should make sure to include Query on the code review for this |