Major - P3 This can be reproduced by starting a standalone mongod with featureFlagSBE and then running the following script:
(function() {
"use strict";
const coll = db.c;
coll.drop();
assert.commandWorked(coll.insert({str: ""}));
const pipeline =
[{"$project": {"a": {"$indexOfCP": [{$literal: ""}, "$str", NumberLong(1)]}, "_id": 0}}];
const resultsWithSbe = coll.aggregate(pipeline).toArray();
function setForceClassic(val) {
assert.commandWorked(db.adminCommand({setParameter: 1, internalQueryForceClassicEngine: val}));
}
const resultsWithoutSbe = (function() {
try {
setForceClassic(true);
return coll.aggregate(pipeline).toArray();
} finally {
setForceClassic(false);
}
}());
assert.eq(resultsWithSbe, resultsWithoutSbe);
}());
This should fail with a message such as the following:
MongoDB server version: 5.0.0-alpha0
uncaught exception: Error: [[ { "a" : -1 }, { "a" : -1 } ]] != [[ { "a" : 0 }, { "a" : 0 } ]] are not equal :
doassert@src/mongo/shell/assert.js:20:14
assert.eq@src/mongo/shell/assert.js:179:9
@repro.js:30:1
@repro.js:1:2
failed to load: repro.js
exiting with code -3
With SBE on, $indexOfCP is returning -1, presumably to indicate that the needle string is not found at any position in the haystack string. With SBE off, the classic engine returns 0. I haven't yet dug into exactly