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  1. Core Server
  2. SERVER-102825

Queries using partial indexes with $or filter can return incorrect results when cache entry exists

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    • Query Optimization
    • Fully Compatible
    • ALL
    • v8.1, v8.0, v7.0, v6.0
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      // Used to create a cache entry
const q1 = [{$match: {$or: [{a: 1}, {a: {$lte: 'a string'}}], _id: {$lte: 5}}}];
// Returns incorrect results once the cache entry is made
const q2 = [{$match: {$or: [{a: 1}, {a: {$lte: 10}}], _id: {$lte: 5}}}];

const coll = db.coll;
assert(coll.drop())
assert.commandWorked(coll.insert({_id: 0, a: 0}))

const expectedResults = coll.aggregate(q2).toArray();
// Matches document

assert.commandWorked(
    coll.createIndex({a: 1}, {partialFilterExpression: {$or: [{a: 1}, {a: {$lte: 'a string'}}]}}))
for (let i = 0; i < 3; i++) {
    coll.aggregate(q1).toArray()
}
const actualResults = coll.aggregate(q2).toArray()
// Does not match document

assert.eq(expectedResults, actualResults, {expectedResults, actualResults})
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      // Used to create a cache entry const q1 = [{$match: {$or: [{a: 1}, {a: {$lte: 'a string' }}], _id: {$lte: 5}}}]; // Returns incorrect results once the cache entry is made const q2 = [{$match: {$or: [{a: 1}, {a: {$lte: 10}}], _id: {$lte: 5}}}]; const coll = db.coll; assert (coll.drop()) assert .commandWorked(coll.insert({_id: 0, a: 0})) const expectedResults = coll.aggregate(q2).toArray(); // Matches document assert .commandWorked( coll.createIndex({a: 1}, {partialFilterExpression: {$or: [{a: 1}, {a: {$lte: 'a string' }}]}})) for (let i = 0; i < 3; i++) { coll.aggregate(q1).toArray() } const actualResults = coll.aggregate(q2).toArray() // Does not match document assert .eq(expectedResults, actualResults, {expectedResults, actualResults})
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      The repro below shows that when we make a cache entry for a query that uses a partial index, a similar query when run after that will return incorrect results.

      No hinting is involved so it is not related to SERVER-26413. It also does not involve $exists or $ne or null, so it seems unrelated to SERVER-36635.

            Assignee:
            ben.shteinfeld@mongodb.com Ben Shteinfeld
            Reporter:
            matt.boros@mongodb.com Matt Boros
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              Created:
              Updated:
              Resolved: