[SERVER-43669] $meta:"sortKey" expressions can generate BSON with duplicate field names which are not correctly handled by Document/Value class Created: 26/Sep/19 Updated: 29/Oct/23 Resolved: 13/Dec/19 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | None |
| Affects Version/s: | None |
| Fix Version/s: | 4.3.3 |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Justin Seyster | Assignee: | Justin Seyster |
| Resolution: | Fixed | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Backwards Compatibility: | Minor Change | ||||||||||||||||||||||||
| Operating System: | ALL | ||||||||||||||||||||||||
| Sprint: | Query 2019-11-04, Query 2019-11-18, Query 2019-12-02, Query 2019-12-16, Query 2019-12-30 | ||||||||||||||||||||||||
| Participants: | |||||||||||||||||||||||||
| Description |
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If a document has a compound sort key (e.g.: {"": 1, "": 2}) and an expression tries to manipulate it, the result may only take one of the fields into account. For example, if the user tries to use {$objectToArray: {$meta: "sortKey"}}, the resulting array only has the first element ( {k: "", v: 1}). I haven't encountered any cases yet, but it's possible that as we use Document/Value more we'll run into internal cases where we are manipulating Documents with duplicate fields. In general, there is no invariant that all field names in a BSONObj are unique, but the only safe way to have a Document with duplicate field names is when you create it from a BSONObj and convert back to a BSONObj with no transformations (so that the lazy conversion behavior just returns the original BSONObj). |
| Comments |
| Comment by Githook User [ 13/Dec/19 ] |
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Author: {'name': 'Justin Seyster', 'email': 'justin.seyster@mongodb.com', 'username': 'jseyster'}Message: |