Partial index isSubsetOf() should recognize equality predicates as subsets of $type partial filters

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    • Type: Improvement
    • Resolution: Unresolved
    • Priority: Major - P3
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    • Affects Version/s: None
    • Component/s: None
    • Query Optimization
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      When a partial index's partialFilterExpression uses $type, the index is not considered eligible for a query with an equality predicate satisfying that type constraint.

      For example,

       

      db.c.createIndex({x: 1},
                 {partialFilterExpression: {x: {$type: "objectId"}}})
db.c.find({x: ObjectId("...")}).explain()
{ ... "winningPlan": { "stage": "COLLSCAN", ... } }

      This query should be eligible to use the partial index.

       

      Proposed solution:

      Add a case to isSubsetOf to handle the case of $eq implying $type.

            Assignee:
            Unassigned
            Reporter:
            Ben Shteinfeld
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              Created:
              Updated: