[SERVER-37194] Number of docsExamined is not considered for index selection Created: 18/Sep/18 Updated: 11/Sep/23 Resolved: 11/Sep/23 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Querying |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Improvement | Priority: | Critical - P2 |
| Reporter: | Alexander Komyagin | Assignee: | Backlog - Query Optimization |
| Resolution: | Duplicate | Votes: | 2 |
| Labels: | bonsai, query-44-grooming | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Assigned Teams: |
Query Optimization
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| Description |
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We should consider the number of documents scanned between different plans being evaluated. At the very least, we should use that to resolve ties between plans. This is critical for Big Data systems reading data via Spark Connector that partitions data by _id for reading. Example: For the query
all indexes below will tie, although it is beyond obvious which one should be selected (the difference is of course dramatic when we're talking about TB's of data):
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| Comments |
| Comment by Alexander Ignatyev [ 11/Sep/23 ] |
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The fix was implemented in PM-3316 via |