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/**
* Tests that the server correctly handles when the OperationContext used by the $lookup stage
* changes as it unwinds the results.
*
* This test was designed to reproduce SERVER-22537.
*/
(function() {
'use strict';
const options = {
setParameter: 'internalDocumentSourceCursorBatchSizeBytes=1'
};
const conn = MongoRunner.runMongod(options);
assert.neq(null, conn, 'mongod was unable to start up with options: ' + tojson(options));
const testDB = conn.getDB('test');
/**
* Executes an aggregrate with 'options.pipeline' and confirms that 'options.numResults' were
* returned.
*/
function runTest(options) {
// The batchSize must be smaller than the number of documents returned by the $lookup. This
// ensures that the mongo shell will issue a getMore when unwinding the $lookup results for
// the same document in the 'source' collection, under a different OperationContext.
const batchSize = 2;
testDB.source.drop();
assert.commandWorked(testDB.source.insert({x: 1}));
testDB.dest.drop();
for (let i = 0; i < 5; ++i) {
assert.commandWorked(testDB.dest.insert({x: 1}));
}
const res = assert.commandWorked(testDB.runCommand({
aggregate: 'source',
pipeline: options.pipeline,
cursor: {
batchSize: batchSize,
},
}));
const cursor = new DBCommandCursor(testDB, res, batchSize);
assert.eq(options.numResults, cursor.itcount());
}
runTest({
pipeline: [
{
$lookup: {
from: 'dest',
localField: 'x',
foreignField: 'x',
as: 'matches',
}
},
{
$unwind: {
path: '$matches',
},
},
],
numResults: 5
});
runTest({
pipeline: [
{
$lookup: {
from: 'dest',
let : {x1: "$x"},
pipeline: [
{$match: {$expr: {$eq: ["$$x1", "$x"]}}},
{
$lookup: {
from: "dest",
as: "matches2",
let : {x2: "$x"},
pipeline: [{$match: {$expr: {$eq: ["$$x2", "$x"]}}}]
}
},
{
$unwind: {
path: '$matches2',
},
},
],
as: 'matches1',
}
},
{
$unwind: {
path: '$matches1',
},
},
],
numResults: 25
});
MongoRunner.stopMongod(conn);
})();
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