Fix caching behavior for SBE plans chosen by CBR

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    • Type: Bug
    • Resolution: Unresolved
    • Priority: Major - P3
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    • Affects Version/s: None
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    • Query Optimization
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      This repro requires the changes of SERVER-116987

      db.foo.drop()
const docs = []
const kNumDocs = 15000
for (let i = 0; i < kNumDocs; i++) {
    docs.push({a: i, b: i});
}
docs.push({a: 7000 + 1, b: 7000 + 1, c: 1});
docs.push({a: 8000 + 1, b: 8000 + 1, c: 1});
db.foo.insertMany(docs);
db.foo.createIndexes([{a: 1}, {b: 1}]);
db.adminCommand({setParameter: 1, planRankerMode: "automaticCE"})
db.adminCommand({setParameter: 1, automaticCEPlanRankingStrategy: "CBRForNoMultiplanningResults"})

// puts plan into cache, with 3 "works" but it should be 4 to represent the 2 keys examined + 2 docs examined
db.foo.aggregate([{$match: {a: 5, b: 10}}, {$group: {_id: "$a", avg: {$avg: "$x"}}}])

// activates plan
db.foo.aggregate([{$match: {a: 5, b: 10}}, {$group: {_id: "$a", avg: {$avg: "$x"}}}])

db.foo.aggregate([{$match: {a: 5, b: 10}}, {$group: {_id: "$a", avg: {$avg: "$x"}}}])
// tassert!
"errmsg" : "Expected variant to hold numReads",
"code" : 8908810,

       

       

      Show
      This repro requires the changes of SERVER-116987 db.foo.drop() const docs = [] const kNumDocs = 15000 for (let i = 0; i < kNumDocs; i++) {     docs.push({a: i, b: i}); } docs.push({a: 7000 + 1, b: 7000 + 1, c: 1}); docs.push({a: 8000 + 1, b: 8000 + 1, c: 1}); db.foo.insertMany(docs); db.foo.createIndexes([{a: 1}, {b: 1}]); db.adminCommand({setParameter: 1, planRankerMode: "automaticCE" }) db.adminCommand({setParameter: 1, automaticCEPlanRankingStrategy: "CBRForNoMultiplanningResults" }) // puts plan into cache, with 3 "works" but it should be 4 to represent the 2 keys examined + 2 docs examined db.foo.aggregate([{$match: {a: 5, b: 10}}, {$group: {_id: "$a" , avg: {$avg: "$x" }}}]) // activates plan db.foo.aggregate([{$match: {a: 5, b: 10}}, {$group: {_id: "$a" , avg: {$avg: "$x" }}}]) db.foo.aggregate([{$match: {a: 5, b: 10}}, {$group: {_id: "$a" , avg: {$avg: "$x" }}}]) // tassert! "errmsg" : "Expected variant to hold numReads" , "code" : 8908810,    
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      When CBR chooses a plan that gets cached, and that plan happens to run in SBE, we run into a tassert because we are storing the number of works in the plan cache entry rather than the number of reads. Note that the accumulator in the repro is necessary to not run into the tassert from SERVER-117093.

        1. make_ranker_choice_work_with_sbe_mp.diff
          11 kB

            Assignee:
            Unassigned
            Reporter:
            Militsa Sotirova
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              Created:
              Updated: